THE EPIDEMIOLOGY OF CLASSICAL SWINE FEVER IN WEST TIMOR, INDONESIA.

By

Petrus Malo Bulu

D.V.M.

School of Veterinary and Biomedical Sciences

Faculty of Health Sciences

Murdoch University

Western Australia

This thesis is submitted for the degree of Research Masters with Training (RMT)

of Murdoch University

2011

I

ABSTRACT

Classical swine fever (CSF) is a serious and highly infectious viral disease of

domestic pigs and wild boar, which is caused by a single stranded RNA pestivirus. A

cross sectional study was carried out on pigs owned by small-holder farmers in West

Timor, in the province of East Nusa Tenggara, Indonesia. The study was designed to

describe the management, husbandry and trading practices adopted by pig farmers in

West Timor, to estimate the seroprevalence of CSF in pigs from selected villages, and

to identify factors associated with seropositivity to CSF. Blood samples were collected

from 720 pigs originating from eight villages in four sub-districts of two districts in

West Timor. A questionnaire survey was administered to the owners of these pigs (n =

240) to gather information from farmers in order to understand management and

husbandry practices and to identify important risk factors for CSF in West Timor.

Pigs are reared under a non-intensive traditional system by small-holder farmers.

Although pigs are an integral component in the economy and have important social and

cultural roles, they receive minimal attention and inputs. These low inputs to pig health

and production are an important constraint to the productivity of pigs in this situation.

In the current study 17.8% (95% CI: 15.1-20.8%) of the pigs were seropositive to CSF.

Three potential risk factors were identified in a multivariable logistic regression model

for the presence of antibodies to CSF. The seroprevalence was higher in herds that had

introduced pigs in the 12 month period preceding the survey (OR 4.78, 95% CI: 1.46,

15.71). Farmers who kept goats were 3.42 (95% CI: 1.20, 9.81) times more likely to

have seropositive pigs than farmers without these animals. Pigs that had been

vaccinated against CSF were also 2.33 (95% CI: 1.10, 5.12)timesmore likely to be

seropositive than were non-vaccinated pigs. The results of the questionnaire highlighted

the lack of implementation of biosecurity measures by small-holder farms in West

II

Timor, which has the potential to increase the risk of their pigs to CSF, as well as to

other diseases.

Although eradication of CSF is the ultimate goal in West Timor, the current

management and husbandry practices adopted by the small-holder farmers, including

extensive unrestricted animal movements, poor farmer knowledge about CSF, low

uptake of vaccination, and poor adoption of biosecurity measures, means that this is

currently improbable. It is recommended that material be developed to educate farmers

about CSF, ways to control it and cost-effective improvements that can be adopted to

improve the management and husbandry of small-holder piggeries.

III

ACKNOWLEDGEMENTS

I especially want to thank my supervisor, Prof. Ian Robertson, for his guidance

during my study and research at Murdoch University. His perpetual energy and

enthusiasm in research has motivated me. In addition, he was always accessible and

willing to help me during my study.

My thanks also goes to Dr. Maria Geong for encouraging, supporting, and

motivating me. She has made available her support in a number of ways during my

research in West Timor. I also wish to thank Dr. Jenny-Ann Toribio for involving me in

the ACIAR project conducted in West Timor.

My keen appreciation goes to Agus Noka, Zulkifli Hmvenani Tabali, and Nola

from theProvincial Dinas Peternakan, drh. Hembang Murni P and her staff from the

local Dinas Peternakan of Kota Kupang, drh.Rofinus and his colleagues fromthe local

Dinas Peternakan of Belu, andMardianes Kale from Politeknik Pertanian Negeri

Kupang for their valuable assistance in the field. Without their help, the field work

would not have been accomplished in time.

I would like to acknowledge Dr. Mahardika and his laboratory staff at the Animal

Biomedical and Molecular Biology Laboratory, Udayana University Denpasar Bali for

their help in testing the samples.

I owe my deepest gratitude to the village chiefs and villages persons in Sikumana,

Oepura, Oebobo and Eobufu in Kota Kupang and Naitimu, Naekasa, Fatukbot and

Lidak in Belu, West Timor for facilitating the surveys. I would particularly like to thank

the pig farmers in West Timor for their understanding and assistance: without them this

study would not have been possible.

IV

Thanks arealso extended to Polly Cocks, Kinzang Dukpa, and Acacio Amaral for

their assistance with the mapping.I wish to thank Edwina Leslie and Emily Drayton for

the collaborative work in West Timor and Bali. I offer my regards and blessings to all of

those who have supported me in any respect during the completion of this study.

It is an honour for me to thank the Department of National Education of Indonesia

through the Directorate of Higher Education which granted me the scholarship to

undertake this study.

My deepest gratitude goes to my family members, especially my wife Fabiana

Lubut, my lovely son JanuardoBaptistaBuluDangga, and my daughter Josephine Clarita

Malo for their unflagging love, support and encouragement throughout my life,

especially during my study in Perth.This dissertation was not possible without their

patience and understanding.

I am indebted to my parents for their endless love, and for sending me to the best

possible education institutions.

Last but not least, thanks be to God for my life and through all the challenges over

the past two years in Perth without my family beside me. You have provided me with

friendly, kind and generous people in Perth, and you have made my life more bountiful.

May your name be exalted, honoured, and glorified around the world.

V

TABLE OF CONTENTS

ABSTRACT. ............................................................................................................... I

ACKNOWLEDGEMENTS ..................................................................................... III

TABLE OF CONTENTS ........................................................................................... V

LIST OF TABLES .................................................................................................. VII

LIST OF FIGURES ............................................................................................... VIII

CHAPTER ONE:INTRODUCTION AND LITERATURE REVIEW .................... 1

1.1 INTRODUCTION ................................................................................................... 1

1.2 HISTORY AND DISTRIBUTION OF CSF ............................................................. 1

1.3 AETIOLOGY OF CSF ............................................................................................ 4

1.4 EPIDEMIOLOGY ................................................................................................... 5

1.4.1 Incubation period ............................................................................................. 5

1.4.2 Survival of the agent ........................................................................................ 5

1.4.2.1 Survival in environment ......................................................................... 5

1.4.2.2 Survival in live animals .......................................................................... 7

1.4.2.3 Survival in animal products and animal by-products .............................. 7

1.4.3 Inactivation of CSFV ....................................................................................... 8

1.4.3.1 Chemical inactivation ............................................................................ 8

1.4.3.2 Phosphate suplemented salt .................................................................... 8

1.4.3.3 Pasteurisation processor or cooking........................................................ 8

1.4.3.4 Thermal inactivation .............................................................................. 9

1.4.4 Agent characteristics ........................................................................................ 9

1.4.5 Forms of CSFV ............................................................................................. 10

VI

1.4.6 Risk factors.................................................................................................... 10

1.4.7 Host species ................................................................................................... 11

1.5DISEASE ............................................................................................................... 13

1.5.1Clinical signs .................................................................................................. 13

1.5.2Prevalence of CSF .......................................................................................... 16

1.5.3Pathology ....................................................................................................... 16

1.5.4Disease transmission ....................................................................................... 18

1.6 CONTROL AND ERADICATION ....................................................................... 20

1.7 ECONOMIC IMPACTS ........................................................................................ 23

1.8 DIAGNOSIS ......................................................................................................... 25

1.8.1Clinical diagnosis ........................................................................................... 25

1.8.2Laboratory tests .............................................................................................. 25

1.8.3Differential diagnosis of CSF .......................................................................... 25

1.9 STUDY AIMS ...................................................................................................... 28

1.10 STUDY OBJECTIVES........................................................................................ 29

1.11 HYPOTHESIS .................................................................................................... 29

CHAPTER TWO:MATERIALS AND METHODS................................................ 30

2.1 INTRODUCTION ................................................................................................. 30

2.2 EXISTING DATA COLLECTION ........................................................................ 31

2.3 STUDY DESIGN .................................................................................................. 31

2.3.1Study type ...................................................................................................... 31

2.3.2 Sampling method ........................................................................................... 32

2.3.3 Sampling Steps. ............................................................................................. 33

2.3.3.1 Step 1-Selection of districts.................................................................. 33

2.3.3.2 Step 2 - Selection of sub-districts ......................................................... 34

2.3.3.3 Step 3 - Selection of villages ................................................................ 35

VII

2.3.3.4 Step 4 - Selection of pig owners ........................................................... 36

2.3.3.5 Step 5 - Selection of pigs ..................................................................... 38

2.3.4 Seroprevalence and Risk Factor Surveys ........................................................ 38

2.3.4.1 Prevalence survey ................................................................................ 38

2.3.4.2 Risk factor survey ................................................................................ 39

2.4 LABORATORY METHODS ................................................................................ 40

2.5 DATA MANAGEMENT ...................................................................................... 40

2.6 DATA ANALYSES .............................................................................................. 40

2.6.1 Univariable analysis....................................................................................... 40

2.6.2 Multivariable analysis .................................................................................... 41

CHAPTER THREE:PIG HUSBANDRY AND MANAGEMENT ......................... 42

3.1 INTRODUCTION ................................................................................................. 42

3.2 MATERIALS AND METHODS ........................................................................... 43

3.2.1 Study area ...................................................................................................... 43

3.2.3 Questinnaire design and implementation ........................................................ 43

3.2.3 Existing data collection .................................................................................. 44

3.2.4 Questionnaire interviews ............................................................................... 45

3.3 RESULTS ............................................................................................................. 45

3.3.1 Pig population in West Timor ........................................................................ 45

3.3.2 Characteristics of pig-owning households and pig husbandry

and management practices adopted ................................................................ 59

3.3.2.1 Characteristics of pig-owning households ............................................ 59

3.3.2.2 Ownership of pigs and other animals .................................................... 59

3.3.2.3 Housing and system of pig raising in West Timor ................................ 60

3.3.2.4 Biosecurity ........................................................................................... 61

3.3.2.5 Feed and drinking water ....................................................................... 61

VIII

3.3.2.6Reproduction management .................................................................... 62

3.3.2.7Body condition score ............................................................................ 63

3.3.2.8Pig movement and trading ..................................................................... 64

3.3.2.9Pig health status, CSF, treatment and prevention ................................... 64

3.4DISCUSSION ........................................................................................................ 45

3.4.1 Pig households characteristics, farm structure and husbandry ......................... 65

3.4.2 Reproductive management and performance .................................................. 69

3.4.3 Movement of pigs .......................................................................................... 71

3.4.4 Pig health, and treatment and prevention of CSF ............................................ 72

3.5 CONCLUSION ..................................................................................................... 74

CHAPTER FOUR:SEROLOGICAL SURVEY FOR CLASSICAL SWINE

FEVER IN WEST TIMOR....................................................................... 75

4.1 INTRODUCTION ................................................................................................. 75

4.2 MATERIALS AND METHODS ........................................................................... 77

4.2.1 Sampling and sample collection ..................................................................... 77

4.2.2 Diagnostic assay ............................................................................................ 78

4.2.2.1 Interpretation and calculation of test results ......................................... 80

4.2.2.2 Statistic analysis .................................................................................. 81

4.3 RESULTS ............................................................................................................. 82

4.3.1 Overall seroprevalence ................................................................................... 82

4.3 DISCUSSION ....................................................................................................... 85

4.4.1 Prevalence of CSF in West Timor .................................................................. 85

4.3 CONCLUSION ..................................................................................................... 90

CHAPTER FIVE:QUESTIONNAIRE AND RISK FACTOR ANALYSIS FOR

CLASSICAL SWINE FEVER IN WEST TIMOR................................ 91

5.1 INTRODUCTION ................................................................................................ 91

IX

5.2 MATERIALS AND METHODS ........................................................................... 92

5.2.1 Data analysis ................................................................................................. 92

5.3 RESULTS ............................................................................................................. 93

5.3.1 Univariable analyses of putative risk factors for CSF in West Timor ............. 93

5.3.2Analysis of variance (ANOVA) for continuous variables .............................. 102

5.3.3Multivariable analysis ................................................................................... 104

5.4 DISCUSSION ..................................................................................................... 105

5.4.1 Characteristics of the interviewed households .............................................. 105

5.4.2 Farm structure and herd information ............................................................ 106

5.4.3 Husbandry and biosecurity practices ............................................................ 107

5.4.5 Reproductive management ........................................................................... 115

5.4.6 Movement of pigs ........................................................................................ 115

5.4.7 Control strategies for Classical Swine Fever ................................................ 116

5.5 CONCLUSIONS ................................................................................................. 119

CHAPTER SIX:GENERAL DISCUSSION .......................................................... 120

6.1 INTRODUCTION .............................................................................................. 120

6.2 PREVALENCE OF CSF IN WEST TIMOR ....................................................... 123

6.3 IMPACT OF CSF IN WEST TIMOR ................................................................. 124

6.4 MODES AND ROUTES OF TRANSMISSION OF CSF .................................... 125

6.5 ERADICATION OF CSF.................................................................................... 127

6.6 CONTROL PROGRAM FOR CSF IN WEST TIMOR ....................................... 128

REFERENCES ......................................................................................................... 136

APPENDIX 1 .......................................................................................................... 167

APPENDIX 2 .......................................................................................................... 184

X

LIST OF TABLES

TABLE 1. 1 CLINICAL SIGNS OF THE DIFFERENT FORMS OF CLASSICAL SWINE FEVER ...... 14

TABLE 1. 2 PREVALENCE OF CSF REPORTED IN VARIUOS COUNTRIES ............................. 17

TABLE 1. 3 STATUS AND CONTROL MEASURES ADOPTED/APPLIED IN SOUTH EAST ASIA . 23

TABLE 1. 4 SENSITIVITY AND SPECIFICITY OF ELISA'S USED TO DETECT CSF ................ 27

TABLE 2. 1 INCLUSION AND EXCLUSION CRITERIAN FOR SELECTION OF ANIMALS............ 32

TABLE 2. 2 FACTORS CONSIDERED WHEN SELECTING DISTRICTS .................................... 33

TABLE 3. 1 PIG POPULATION IN WEST TIMOR ............................................................... 46

TABLE 3. 2 FREQUENCY OF HUSBANDRY AND MANAGEMENT PRACTICES ADOPTED BY PIG

FARMERS IN WEST TIMOR..................................................................................... 46

TABLE 3.3 NUMBER OF LIVESTOCK OWNED BY THE INTERVIEWED HOUSEHOLDS ............ 57

TABLE 3.4 LITTER SIZES OF PIGS IN INTERVIEWED HOUSEHOLDS OVER THE 12 MONTH

PERIOD PRECEDING THE SURVEY ........................................................................... 58

TABLE 4.1 NUMBER OF FARMERS INTERVIEWED AND PIGS SAMPLED PER VILLAGE .......... 77

TABLE 4.2 TEST SEROPREVALENCE OF CSF IN WEST TIMOR ......................................... 83

TABLE 4.3 HERD LEVEL PREVALENCE OF CSF IN THE VILLAGES, SUBDISTRICTS AND

DISTRICTS SAMPLED. ............................................................................................ 84

TABLE 5. 1 RISK FACTORS FOR CSF IN WEST TIMOR (CATEGORICAL VARIABLES) . ........ 94

TABLE 5. 2 RISK FACTORS FOR CSF IN WEST TIMOR (CONTINUOUS VARIABLES). ......... 103

TABLE 5.3 MULTIVARIABLE ANALYSIS OF POTENTIAL RISK FACTORS FOR CSF IN WEST

TIMOR ............................................................................................................... 105

XI

LIST OF FIGURES

FIGURE 1. 1 DISTRIBUTION OF CSF ................................................................................ 3

FIGURE 1. 2 DISTRIBUTION OF CSF IN INDONESIA .......................................................... 3

FIGURE 2. 1 SELECTED DISTRICTS (KABUPATEN) IN WEST TIMOR COLOURED AS YELLOW

(BELU AND KOTA KUPANG). ................................................................................ 34

FIGURE 2.2 SELECTED SUB-DISTRICTS (KECAMATAN) IN THE DISTRICTS OF KOTA KUPANG

(OEBOBO AND MAULAFA) AND BELU (TASIFETO BARAT AND KOTA ATAMBUA) .... 35

FIGURE 2. 3 SELECTED VILLAGES (KELURAHAN/DESA) IN THE SUB-DISTRICS OF MAULAFA

(SIKUMANA AND OEPURA) AND OEBOBO (OEBOBO AND OEBUFU) IN THE DISTRICT

OF KOTA KUPANG. ............................................................................................... 36

FIGURE 2. 4 SELECTED VILLAGES (KELURAHAN/DESA IN THE SUB-DISTRICTS OF TASIFETO

BARAT (NAITIMU AND NAEKASA) AND ATAMBUA SELATAN (FATUKBOT AND LIDAK)

IN THE DISTRICT OF BELU. .................................................................................... 37

FIGURE 3. 1 FACE TO FACE FARMER INTERVIEW IN THE DISTRICT OF BELU .................... 44

FIGURE 3. 2 EQUIPMENT USED FOR COOKING SWILL IN A FARMER'S HOUSE IN KOTA

KUPANG .............................................................................................................. 62

FIGURE 3. 3 WEANER PIGS IN BELU .............................................................................. 63

FIGURE 3. 4 PIG IN POOR BODY CONDITION ................................................................... 70

FIGURE 4.1 ELISA TEST PROCEDURE ............................................................................ 79

FIGURE 4.2 THE TEST PROCEDURE FOLLOWED FOR TESTING SAMPLES IN THE AB&MB

LABORATORY AT THE UNIVERSITY OF UDAYANA, DENPASAR, BALI. ..................... 81

FIGURE 5. 1 PIG HOUSE MADE FROM EASILY ACCESSIBLE MATERIALS IN KOTA KUPANG

.......................................................................................................................... 111

FIGURE 5. 2 PIG TETHERED IN THE HOUSE-YARD OF A PIG OWNER ................................ 111

FIGURE 5. 3 PIG HOUSE IN BELU ................................................................................. 112

FIGURE 5. 4 RAISED PIG HOUSE IN BELU WITH A FREE ROAMING PIG............................. 112

1

CHAPTER ONE

INTRODUCTION AND LITERATURE REVIEW

1.1 Introduction

The epidemiological aspects of classical swine fever (CSF) in West Timor, East Nusa

Tenggara, Indonesia are investigated in this thesis. Accordingly, this literature review is set

out to give an introduction to the general and specific topics covered. To do this it starts

with an overview of the background/history of CSF, and then describes major

developments in research into the distribution of the disease during the last century. Finally,

it focuses on the disease, examining its epidemiology, clinical signs and pathology, control

and eradication programs, risk factors for its spread and the various laboratory techniques

that are used to diagnose the disease.

1.2 History and Distribution of CSF

Classical Swine Fever virus (CSFV) is one of the three pestiviruses that forms a

group of economically important pathogens (Moennig et al. 1990). Classical Swine Fever

is a serious and highly infectious viral disease of domestic pigs and wild boar (Paton and

Greiser-Wilke 2003). The disease is also known as Hog Cholera (HC) in the USA and

Swine Fever (SF) or “European” swine fever in Europe, and needs to be differentiated from

African Swine Fever (ASF), which is caused by an icosahedral double stranded DNA virus,

the sole member of the new genus Asfivirus in the family Asfarviridae (CFSPH 2010;

Denyer and Wilkinson 1998; Dixon and Chapman 2008; Dixon et al. 2000).

The OIE officially calls the disease Classical Swine Fever (Animal Health Yearbook

1978) and the infectious agent Hog Cholera virus (HCV) (Fenner 1976). Classical Swine

2

Fever was first reported in the 1930’s in the midwest of the USA (Moennig 1990; Moennig

2000), although anecdotally it was seen in the state of Ohio as early as 1833 (Dahle and

Liess 1992; Moennig and Greiser-Wilke 2008). The origin of the disease was reviewed by

Hanson (1957) who stated that the disease originated in Europe and was introduced into the

USA through the importation of new breeds of pigs. However, this was refuted by

European authorities (Dahle and Liess, 1992), and consequently the real origin/source of

the virus remains uncertain.

The disease has, at some point of time, been distributed throughout the world

including North and South America, Europe, Asia, Africa and Australia (Figure 1.1).

However, several countries, including Australia, Canada, New Zealand, USA, and some

European Union (EU) countries have succeeded in eradicating it (Dahle and Liess 1992;

Moennig 2000). Eradication was successfully implemented in Australia in 1963, Canada in

1964, USA in 1977, and France, Greece, Luxembourg, Netherlands, Portugal, Spain, and

the UK at the end of 1989 (Dahle and Liess 1992). Furthermore in 1990, Italy the last

member state of EU vaccinating ceased this practice, and since then it has been free from

CSF (Saatkamp et al. 2000). Unfortunately, CSF outbreaks have continued to occur in

densely populated pig regions such as Germany and Belgium (Dijkhuizen and Davies

1996).

3

Figure 1.1 Distribution of CSF source: OIE (2011)

Figure 1.2 Distribution of CSF in Indonesia source: OIE (2011)

4

1.2.1 Status of CSF in Indonesia

In Indonesia, CSF has been a significant problem for pig farmers and is found

throughout the country (Figure 1.2). Indonesia was a CSF free country until 1993. The

introduction of CSF to Indonesia occurred in 1994 and between 1994 and 1996 thousands

of pigs died in some parts of the country, specifically North Sumatera, Jakarta, Bali, Central

Java, and North Sulawesi (Satya and Santhia2009). The first reported outbreak of CSF was

in the province of North Sumatera in the districts of Dairi and Simalungun (Anon 1996,

1998). It has been proposed that the disease was introduced from the Northern Malaysia

Peninsular (where the disease was known to occur) through the movement of pigs, as at that

time there were reports that pigs had been introduced to North Sumatera from this area. The

disease was reported in Padang in the western part of Sumatera in August 1995 and in the

same year, the disease was introduced to the islands of Java and Bali through the

introduction of pigs (Satya and Santhia 2009).

1.2.2 Status of CSF in West Timor

An outbreak of CSF was reported in Dili, East Timor in August 1997 (when it was

part of Indonesia) and then spread to the Kupang district in March 1998 (Satya et al. 2009)

and subsequently the disease has been reported in all districts of Timor (Santhia et al. 1997;

Santhia et al. 1998).

1.3 Aetiology of CSF

The causative agent of CSF is a small (40±60 nm) enveloped ribonucleic acid (RNA)

virus with a single stranded RNA genome with positive polarity (Horzinek et al. 1971;

Moenning 1992;Moennig and Greiser-Wilke, 2008; Moormann et al. 1996; Paton and

5

Greiser-Wilke 2003). The virus (CSFV) belongs to the genus pestivirus of the Flaviviridae

family (Wengler 1991; Wengler etal. 1995). This virus has a close antigenic relationship

with bovine viral diarrhoea virus (BVDV) and border disease virus (BDV), as demonstrated

by immunodiffusion and immunofluorescence tests, and their similar morphology and

nucleic acid homology. Initially they were placed in a genus within the family Togaviridae

(Horzinek 1973; Westaway et al. 1985), however, recently they were allocated to the

family Flaviviridae based on their replication and genomic organisation (Horzinek 1991).

1.4 Epidemiology

1.4.1 Incubation period

The incubation period for CSF depends primarily on the virulence of the virus (Blaha

1989) and is generally between 2 and 10 days (Moennig and Greiser-Wilke 2008). Pigs

exposed to CSFV in utero may be persistently infected but often don’t display any signs of

disease until they are several months old. Pigs exposed postnatally are usually infective

between 5 and 14 days post-infection (pi), however with chronic infections this infective

stage can last for up to 3 months (OIE 2008).

1.4.2 Survival of the Agent

1.4.2.1 Survival in environment

The stability of CSFV in the environment is of particular importance, since

experience has shown that many outbreaks of the disease may be caused by vector-

mediated spread of the virus (Moennig 1992). The virus may survive for long periods in

manure, and experimental studies have suggested that inactivation occurs more rapidly in

6

liquid manure than in solid manure (Have 1984). Survival time in various types of water

has been reported to vary from 6 to 24 days at 20°C (Pagnini et al. 1984).

The virulence of the strains circulating in the field and the measures applied to

control the disease determine, to a large extent, the course of an epidemic. Outbreaks of

disease caused by highly virulent strains are easily recognised by the sudden onset of high

mortality and morbidity. In contrast, epidemics caused by low virulent strains are

characterised by indistinct signs of disease, slow spread of virus through the herd and the

comparatively important role of the 'carrier sow syndrome'. The latter phenomenon may

result in the birth of healthy looking, but persistently infected, immune-tolerant piglets.

This, and the occurrence of chronic infections, is largely responsible for the perpetuation of

the virus in the pig population (Terpstra 1988). In addition, CSFV, like many enveloped

viruses, may be regarded as moderately fragile. It shows a short but variable survival time

in the environment, depending on the physical conditions present, but importantly may

remain viable for prolonged periods in favourable circumstances, for example, in stored

meat (Edwards 2000).

The infectivity of CSFV can be inactivated by elevated temperature e.g. 10 min at

60°C, by ultraviolet radiation (Kubin 1967), and due to its lipid envelope, detergents and

lipid solvents (Loan 1964; McKissick and Gustafson 1967). One study conducted by

Weesendorp et al. (2008), examined the survival of CSFV in faeces and urine derived from

pigs that had been challenged through the intranasal route with a highly or moderately

virulent strain of CSFV. Their results demonstrated that the inactivation rate was inversely

related to the storage temperature. The average half-life for the virus was between 2 and 4

days at 5°C, and only 1 to 3 hr at 30°C. Significant differences were observed in the

survival of virus in faeces kept at different temperatures, however not with virus in urine.

7

The virus remains infective in a relatively wide pH range. At pH 3, the mean half-life

has been shown to be more than tenfold lower when the virus was kept at an ambient

temperature of 21°C when compared with 4°C. Additionally at 4°C, the half-lives of some

strains/isolates tested, were four to ten times lower when the pH was raised from 3 to 4.

The average half-life of a virus suspension at pH of 4.0 and at 4°C was 260 hr. When the

temperature was increased to 20-22°C the half-life was reduced to 11 hr (Depner et al.

1992). In aerosols the virus remains infective for at least 30 min with half-life time values

ranging from 4.5 to 15 minutes (Weesendorp et al. 2008).

1.4.2.2 Survival in live animals

During the incubation period, the virus can be shed by infected pigs, and the viral

excretion continues until the pig dies, or until specific antibodies have developed in the

surviving pigs (AusVetPlan 2009). In addition, the virus is shed continually or

intermittently for a short period of time in the case of subacute and subclinical infections

(Van Oirschot and Terpstra 1989). Piglets born to carrier sows can shed large quantities of

the virus for months without showing clinical signs or developing an immune response

(Terpstra 1994).

1.4.2.3 Survival in animal products and animal by-products

Classical swine fever virus is relatively stable in moist excretions and fresh meat

products, including ham and salami type sausages (Savi et al. 1965). The virus has been

reported to survive for more than 4 years in frozen pork (Edgaret al. 1949), while in chilled

fresh pork it can survive for up to 85 days (Birch 1917; Doyle 1933; Helwig and

Keast1966).

8

However, the virus is readily inactivated by heat, detergents, lipid solvents, proteases

and common disinfectants (Edwards et al. 2000). In addition, CSFV is readily killed by

pasteurisation processes or by cooking (Stewart et al., 1979; McKercher et al. 1987).

1.4.3 Inactivation of CSFV

1.4.3.1 Chemical inactivation

Classical swine fever virus can be inactivated by organic solvents, such as ether or

chloroform, detergents such as Nonidet P40, deoxycholate, or saponin (Moennig 1988) and

a wide range of chemicals, including chlorine-based disinfectants, detergents, phenolics,

quaternary ammonium compounds, and aldehydes (formaldehyde, glutaraldehyde) (Liess

and Schurian 1973; Russell and Hugo 1987), because it has a lipid-containing envelope

(AusVetPlan 2009).

1.4.3.2 Phosphate supplemented salt

Pig intestines used for the production of natural sausage casings may carry CSFV,

therefore feeding pigs with human food waste that contains pig casings may spread virus to

CSF-free animals (Wijnker et al. 2008). These authors recommended that porcine sausage

casings should be stored in a phosphate supplemented salt for 30 days at a temperature of

approximately 4°C in order to inactivate CSFV and to avoid the inadvertent spread of virus.

1.4.3.3 Pasteurisation processes or cooking

The virus can be killed by pasteurisation or thorough cooking. Treatment of virus-

contaminated meat for 30 min at 65°C or 1 min at 71°C rendered it non-infective (Helwig

and Keast 1966; McKercher et al. 1978; Stewart et al. 1979). Blood contaminated at

9

105TCID50/ml was inactivated at temperatures of 66°C for 60 min, 68°C for 45 min, or

69°C for 30 min (Edwards 2000).

1.4.3.4 Thermal inactivation

Thermal inactivation curves may be derived for the virus at different temperatures but

may vary with the virus strain (Depner et al. 1992; Kubin 1967). Inactivation occurred in 1

min at 90°C, 2 min at 80°C, and 5 min at 70°C (ur Rehman 1987).

1.4.4 Agent characteristics

Classical swine fever virus can cause persistent infections in pigs (Van Oirschot and

Terpstra 1977). Pigs that are infected in utero can be persistently infected (Van Waveren et

al. 1956). The infection is characterized by persistent viraemia, continuous virus excretion

and late onset of disease, with death occurring 2 to 11 months after birth. The average

survival time for piglets infected in utero has been reported to be over six months (Van

Oirschot and Terpstra 1977).

Although the course of infection with CSFV is often subclinical, the virus can cross

the placenta of pregnant sows, thereby infecting foetuses during all stages of development

(Moennig et al. 2003). In addition, the outcome of infection depends on the virulence of the

virus strain and the gestation stage of the sow. Infection of sows early in pregnancy may

result in abortions, stillbirths, mummifications and malformations. Infection between 50

and 70 days of gestation can lead to the birth of persistently viraemic piglets, which are

clinically normal and survive for several months (Moennig et al. 2003).

Van Oirschot (1999) demonstrated that sows infected with low virulent strains of

CSFV 40 days after mating had litters with higher prenatal mortality. In contrast litters

infected 65 days after mating had more postnatal deaths. For this latter group three sows

10

produced completely infected litters, whereas another five produced litters with some non-

infected piglets. Twelve piglets recovered from the infection and the percentage of piglets

recovering increased with the stage of pregnancy at which the infection took place. Twenty-

three piglets developed a persistent infection. Consequently Van Oirschot (1999) concluded

that the later sows are infected during pregnancy, the more non-infected piglets born. On

the other hand, the earlier infection occurred during pregnancy, the more persistent

infections were produced.

1.4.5 Forms of CSFV

There are four forms of CSF: peracute, acute, subacute, and chronic forms (Dahle

and Lies 1992). These forms result in different morbidity and mortality. The peracute form

yields a high morbidity and mortality within 5 days PI and the acute form results in death

between 10 and 20 days PI (Mengeling and Cheville 1968). In addition, catarrhal, fibrinous,

and haemorrhagic inflammatory reactions are present in the digestive, respiratory, and

urogenital tracts (Blaha 1989; Van Oirschot 1999). Mortality can be as high as 90 to 100%

in the peracute and acute forms (Blaha 1989). The subacute and chronic forms show a

greatly varying clinical picture, with local inflammation of the respiratory and digestive

tract (Blaha 1989). The subacute form results in death between 20 and 29 days PI

(Mengeling and Cheville 1968); while the chronic form results in death after 30 or more

days PI (Dunne 1973).

1.4.6 Risk Factors

According to Moennig and Greise-Wilke (2008) the feeding of untreated swill

(kitchen waste) that contains infected pork is a major source of primary outbreaks in

regions previously free from CSF. Swill feeding has been officially banned in almost all

11

CSF-free countries; however often awareness of the risk factors and knowledge of the

legislation are not sufficient to prevent an outbreak as some farmers continue to illegally

feed swill (Fritzemeier et al. 2000). Other important factors for the transmission of the virus

from infected pigs include contact with wild boar, and poor management and biosecurity,

including a lack of suitable hygienic measures allowing exposure to contaminated fomites.

Epidemiological investigations and virus typing has provided strong evidence that infected

wild boar have been the source of numerous outbreaks in Europe (Fritzemeier et al. 2000).

The spread of the disease is facilitated by the movement of virus excreting pigs. The

purchase of weaner pigs from different breeding farms or from markets carries a high risk

of introducing the virus into susceptible populations (Beals et al. 1970).

As well as infection with CSFV, pigs can also be infected with the ruminant

pestiviruses, BVDV and BDV.The presence of cattle on the same premises and a high

density of sheep and/or goat herds within 3 km of the pigs have been identified as important

riskfactors associated with a BVDV-seropositive status in breeding pigs. In addition,

serological cross-reactions occur between the pestiviruses, providing potentially protective

immunity, but also leading to confusion in the interpretation of the results from diagnostic

tests (Loeffen et al. 2009).

Based on research conducted by Elbers et al. (2001) five factors have been identified

that can be associated with the introduction of CSFV into pig herds:

1) Presence of other species on the premises besides pigs;

2) Visitors enter pig units without wearing protective clothing and footwear provided by the

farm;

3) Drivers of trucks used for transporting pigs wearing their own boots rather than boots

provided by the farm;

12

4) A moderate herd size (500-1000 animals) and a very large herd size (> 7000 animals)

compared with a small herd size (< 500 animals);

5) Aerosols generated during high-pressure cleaning which can be dispersed at least 250

metres by wind.

1.4.7 Host Species

Pestiviruses are not strictly host-species specific and can infect not only domestic

but also wild animals. Members of the family Suidae, in particular domestic pigs (Sus

scrofa domesticus) and European wild boar (Sus scrofa scrofa), are the natural hosts of

CSFV (Krinsky 1976). Wild boar are found in many countries and are known reservoirs for

a number of viruses, bacteria and parasites that are transmissible to both domestic animals

and humans (Meng et al. 2009). Infection of wild pigs with CSFV may complicate the

success of an eradication program (Vilcek and Nettleton 2006). The virus can be

experimentally transmitted to probably all ruminants, but with certainty to goats, sheep,

calves and deer (Dahle et al. 1987).

One study conducted in 11 species of wild and domesticated animals by Loan and

Storm (1968) showed that antibody production to CSFV was not detected in wild mice

(Mus spp.), cottontail rabbits (Sylvilagus sylvilagus), sparrows (Passer spp.), wild rats

(Rattus spp.), raccoons (Procyon lotor), or pigeons (Columba livia) after inoculation with

virus. In contrast significant antibody production was detected in peccaries (Tayassu

tajacu), calves, goats, sheep and deer (species not specified) inoculated with the virus.

Moennig (1990) highlighted the relative ease with which Pestiviruses are able to cross

the species barriers. Many studies have shown that CSFV can be experimentally

transmissible to cattle and small ruminants and BVDV naturally infects pigs, sheep, goats

and a wide range of wild ruminants (Dahle et al. 1987; Doyle and Heuschele 1983;

13

Nettleton et al. 1980; Snowdon and French 1968). In a survey conducted in pigs in

Northern Germany 15-20% of all breeding pigs were found to be seropositive to BVDV

(Liess et al. 1976). Such cross-species transmission can be important when interpreting the

results from a serological surveillance study.

1.5 Disease

1.5.1 Clinical signs

The clinical signs of CSF vary with the strain of virus, the age of pig affected and the

immune status of the pigs. More virulent strains cause acute disease; less virulent strains

can result in a high percentage of chronic, mild or asymptomatic infections. Although

highly virulent strains were once more prevalent, most epizootics are now caused by

moderately virulent strains. Some breed-specific differences have also been reported. All

feral and wild pigs, including European wild boar (Sus scrofa scrofa) and collared peccaries

(Pecari tajacu), are thought to be susceptible (CFSPH 2009). In older breeding pigs the

infection is often mild or subclinical. However, the diagnosis of CSF based on clinical

signs alone is often difficult as the signs may vary considerably (Depner et al. 1997;

Moennig and Plagemann 1992; Van Oirschot 2003). Anorexia, fever, conjunctivitis,

constipation, diarrhoea, hyperaemia of the skin, posterior paresis, convulsions, and purplish

discoloration of the abdomen, snout, ears and medial sides of the legs have all been

observed in infected pigs (Ruiz-Fons et al. 2008). The typical haemorrhages of the skin

associated with the disease are usually observed during the second and third week after

infection until death (Moennig et al. 2003). The virus is shed from the infected animal in

the saliva, urine and faeces (Laevens et al. 1999).

The virulence of a CSFV isolate is difficult to determine on a rational basis

(Mittelholzer et al. 2000). However, acute, chronic and prenatal forms of CSF occur. The

14

acute form is most often seen in piglets up to the age of 12 weeks. A constant finding is

pyrexia, usually higher than 40°C; however often in adults the temperature does not exceed

39.5°C. Anorexia, lethargy, conjunctivitis, enlarged and discoloured lymph nodes,

respiratory signs and constipation followed by diarrhoea are the initial signs of CSF.

Animals may display incoordination, weakness of the hind limbs and convulsions. The

main clinical signs of the different CSF forms are summarised in Table 1.1.

Table 1.1 Clinical signs of the different forms of Classical Swine Fever

Infection time Virulence Form of

CSF Clinical signs References

Postnatal High

Peracute

Characterized by a rapid course without typical clinical signs for CSF followed by sudden death A high morbidity and death within 5 days post infection Young pigs may be found dead without any prior sign of illness especially at the beginning of an outbreak. Death within 24-48 hours preceded by lethargy. Mortality can reach 100%

AHP 2010; Dunne 1973; Everett et al. 2010; Fuchs 1968; Pig disease information centre 1996

Acute

Fever (39.5–42°C) AusVetPlan 2009; Moennig and Greiser-Wilke 2008

Initial signs are anorexia, lethargy, huddling together, conjunctivitis, respiratory symptoms, and constipation followed by diarrhoea

AusVetPlan 2009; CFSPH 2009; Moennig and Greiser-Wilke 2008

Incoordination, stiff gait, inability or unwillingness to stand, convulsions

AusVetPlan 2009 Hyperaemia or cyanosis of extremities, particularly ears and snout

15

Infection time

Virulence Form of CSF

Clinical signs References

Death occurs 2-3 weeks after infection Moennig 2000

Laboured breathing, coughing

AusVetPlan 2009

Abortion, mummifications, stillbirth and foetal abnormalities Case fatality rate up to 100% Dysentery or diarrhoea, conjunctivitis, nasal discharge, and vomiting Neutralizing antibodies against CSFV become detectable 2–3 weeks post infection.

Moennig and Greiser-Wilke 2008

Severe leucopaenia AusVetPlan 2009

Moderate Chronic

Fever (> 40.5°C), which may fluctuate irregularly

Animals usually survive for 2 to 4 months before death

Moennig 2000; Moennig and Greiser-Wilke 2008

Pneumonia, coughing AusVetPlan 2009 Lower case fatality rate than the

acute form Antibodies may be temporarily detected in serum samples, as the immune system begins to produce antibodies

Moennig 2000; Moennig and Greiser-Wilke 2008

Prenatal Low Subacute

Infection during early pregnancy may result in abortions and stillbirths, mummifications and malformations

Moennig et al. 2003; Moennig and Greiser-Wilke 2008

Infection of sows from about 50 to 70 days of pregnancy may lead to the birth of persistently viraemic piglets, which may be clinically normal at birth and survive for several months.

Moennig and Greiser-Wilke 2008

After birth, piglets usually show poor growth (‘runt’), wasting, or occasionally a congenital tremor. Death occurs 2-11 months after infection Van Oirschot 1999

16

1.5.2 Prevalence of CSF

Many other studies have reported on the prevalence of CSF in different countries in

both wild and domestic pigs. In the Netherlands, a survey on wild boar found that 11 of 116

(9%) wild boars were seropositive for CSFV (Stegeman et al. 2000), similarly in French

wild boars tested from 1991 to 1998, 80 out of 12,025 (0.7%) were seropositive (Albina et

al. 2000). Additionally, in France during the two outbreaks of CSF in wild boar from 2002

and 2003, of the 3337 samples tested 188/2525 (7·45%) were positive on the ELISA,

65/152 (42·8%) were positive to the virus neutralisation test (VNT), 70/1707 (4·1%) were

positive by PCR, and 15/84 (17·9%) had virus isolated (Pol et al. 2008). A summary of the

prevalences reported in various studies CSF is presented in Table 1.2.

1.5.3 Pathology

After infection, virus replication takes place in the spleen, bone marrow, and visceral

lymph nodes. The cells of the immune system are the main target of the virus resulting in

immunosupression. Once the disease develops, pathological changes visible on post

mortem examination are observed, most often in the lymph nodes, spleen and kidneys in

acute cases. The lymph nodes become swollen, oedematous and haemorrhagic.

Haemorrhages in the kidney may vary in size from hardly visible petechiae to ecchymotic

haemorrhages, and frequently occur on the surface of the cortex resulting in the

characteristic “turkey kidney” pathological lesion, but are less common in the medullary

pyramids and hilus. Kidney parenchyma may display a yellowish brown colour. Petechiae

can also be observed in the urinary bladder, larynx, epiglottis and heart, and may be

widespread over the serosa of the abdomen and chest (Van Oirschot 1999). A non-purulent

encephalitis is often also present (Gruber et al. 1995). Infarctions of the spleen are

considered to be pathognomonic for CSF, however they are rarely observed. These infarcts

17

are a result of a disrupted blood flow to certain areas resulting from the occlusion of blood

capillaries by thrombi (Sato et al. 2000). In the spleen severe atrophy of the splenic

corpuscles, swollen reticular cells in the mantle zone and follicular necrosis (which is a

typical lesion of CSF) are observed on histology. In pigs with persistent CSF, the most

outstanding lesions are severe atrophy of the thymus and depletion of the lymphocytes and

germinal follicles in the peripheral lymphoid organs (Sato et al. 2000).

Table 1.2 Prevalence of CSF reported in variuos countries

Country Type of pig Number of samples tested (% positive)

Reference

Croatia wild boars 259 (46.7%) 44 (36.6%)

Roic et al. 2006 Zupancic et al. 2002

Switzerland wild boars 1294 (14.0%) Schnyder et al. 2002 Germany (The federal states Sachsen-Anhalt and Brandenburg)

wild boars 659 (5.0%) Oslage et al. 1994

Chile domestic pigs 1951 (9.7%) APFRAN GARZPA 2002

Netherlands domestic pigs wild boars

135,000 (64.0%) 116 (9.0%)

de Smit et al. 2000 Stegeman et al. 2000

French (Brittany) domestic pigs N/A (46.0%) Ellis et al. 1977 Indonesia (East Flores- NTT) domestic pigs N/A(30.9%) Santhia et al. 2001

Northern provinces of Lao PDR: Oudomxay Prabang Phongsaly Xayabouly Houaphan

domestic pigs

55 (11.0%) 91 (13.0%) 88 (15.0%) 84 (15.0%) 161 (6.0%)

Khounsy and Conlan 2008

18

1.5.4 Disease Transmission

With respect to agent (viral) factors, virulence and mutation are important factors

for disease transmission (Risatti et al. 2005). In addition, an association may exist between

virulence and antigenicity, where strains that are antigenically related to BVDV appear to

be less virulent. Infection with highly virulent CSFV strains generally leads to death of

infected animals, whereas isolates of moderate to low virulence induce a prolonged chronic

disease (van Oirschot 1986).

In terms of host factors, the transmission of CSF is enhanced by many factors

including: movement of virus excreting pigs within a population, population density,

presence of susceptible and reservoir hosts, age structure of the population, and iatrogenic

factors (Dahle and Liess 1992). Persistent infections are the most important mechanisms by

which the disease perpetuates in the domestic pig population (Liess, 1984). Persistent

infections are commonly established during gestation at a time when the immune response

of the foetus is not capable of eliminating the virus. The optimal time for the establishment

of persistent viraemia depends on the maturation of the foetal immune system (Moennig

1990). In addition to host factors, transmission of the CSFV occurs via direct and indirect

routes including through contaminated fomites (Karsten et al. 2005). With respect to spread

via vehicles, trucks play a major role in the transmission of CSFV. For example in the

Netherlands it was estimated that approximately 39 herds were infected before the first

measures of an eradication campaign came into force (Elberset al. 1999). Transportation of

weaners originating from different breeding farms and redistributed to fattening farms is a

significant risk factor for the spread of disease. Such transportation, often over long

distances, may result in a large number of non-traceable contacts (Terpstra 1991). In

19

Indonesia, CSF is thought to be spread by the movement of live pigs and pig products

(Christie 2007).

Acute, chronic or congenital infection can occur (Dahle and Liess 1992). Congenital

infections, in which the piglets are born `healthy', from an epidemiological point of view,

are the most dangerous. These piglets may shed large quantities of virus for months without

showing signs of disease or developing an antibody response (Van Oirschot and Terpstra

1977). The main route of infection in field cases is via the oronasal route (Moennig 2000),

by either direct or indirect contact with infected pigs or through contaminated feed, e.g.

swill. In areas with a high density of pigs, virus spreads easily between neighbouring pig

holdings (Fritzemeier et al. 2000; Terpstra 1988). The ingestion by pigs of pig meat

products infected with the virus is an important method for the spread of CSF, and often is

the cause of the first outbreak in a country. Farmers, veterinarians, inseminators and

castrators potentially could also transmit CSF through the use of contaminated instruments.

Use of hypodermic needles on more than one pig or more than one farm is also a very

important method of spread. The disease can also spread when vaccinating teams do not

discard partially used bottles of vaccine when moving from farm to farm (AusVetPlan

2009).Disease transmission via the semen of infected boars may also occur (AusVetPlan

2009; Elberset al. 1999; Floegel et al. 2000).

Tabanids are potential mechanical vectors of CSFV (Krinsky 1976). However,

CSFV is not transmitted biologically by any arthropod vectors, but it may be spread

mechanically by arthropods as well as through scavengers such as dogs or wild birds

(AusVetPlan 2009). Feral pigs (wild boar) can be infected by the virus, and it is therefore

necessary to minimise contact between feral and domestic pigs by ensuring secure

boundary fencing (Weesendorp et al. 2008; AusVetPlan 2009).

20

1.6 Control and Eradication

Classical Swine Fever is classified as a notifiable disease in most countries. The

strategy for the prevention, control and/or eradication of the disease in domestic pigs differs

between countries and can be summarised as follows (Edwards et al. 2000):

1. In countries previously free from CSF a non-vaccination policy, combined with a total

stamping-out, in the case of disease outbreaks and eventual preventive slaughter of

pigs in suspect and in-contact farms, is applied as necessary. Serological surveillance

is undertaken in the domestic pig population. The surveillance system and number of

samples collected depends on the prevalence of CSF, the wild boar population and

the epidemiological situation of neighbouring countries.

2. In countries where the disease is endemic control is generally based on vaccination. In

some countries, the decision to use vaccination depends on the ownership or on the

size of the farms. Programs of vaccination can vary as can the type of vaccines used

in different countries. In some countries (e.g. Russia), it is recommended to vaccinate

3-week-old piglets, whereas in others (e.g. Bulgaria, Romania) pigs are not

vaccinated until 10-12 weeks of age.

3. Legislation should be in place to prohibit the importation of pigs from infected

countries.

4. Quarantine measures and restrictions on the movements of pigs need to be employed

within infected countries to control the spread of the disease.

5. Other precautions include slaughter of infected herds (although this may not be

possible due to financial restrictions), and establishment of protection (approximately

3 km radius) and surveillance zones (approximately 10 km radius) around infected

farms to control the spread of the disease.

6. Swill feeding needs to be regulated.

21

Control and prevention strategies, specifically in relation to sanitary and medical

prophylaxis, and responses to outbreaks have been outlined by the OIE (2002). In relation

to sanitation the OIE suggested the following strategies:

1. Effective communication between veterinary authorities, veterinary practitioners and

pig farmers should be established.

2. The disease reporting system should be effective and the policy for the importation of

live pigs, and fresh and cured pig meat should be strictly implemented.

3. Pigs should be quarantined before admission into a herd.

4. Waste food or swill should be prohibited to be fed to pigs or if it is fed it must be

properly sterilised.

5. Efficient control of rendering plants should be established.

6. Structured serological surveillance should be undertaken that is targeted at breeding

sows and boars.

7. An appropriate pig identification and recording system should be implemented.

In areas where CSF is endemic, vaccination with modified live virus strains is

recommended (CFSPH 2009; Suradhat et al. 2007; Van Oirschot 2003). In contrast in

countries which are free of disease, or where eradication is in progress, vaccination is

normally prohibited (Van Oirschot 2003).

To eradicate CSF from a pig population, the transmission needs to be reduced to such

an extent that the virus cannot maintain itself in the population. This might be obtained by

control measures including slaughtering infected herds, culling of herds at risk, vaccination,

improved hygiene measures and movement restrictions (Moennig 2000). The most

important control measures are the culling of infected herds, prohibition of transport, the

22

tracing and testing of infectious contacts, and the implementation of hygienic measures and

surveillance in the affected area (Klinkenberg et al. 2003). However, the program adopted

to control CSF can vary significantly from country to country. The control policy depends

upon the incidence and prevalence of the infection in both the domestic and wild pig

populations. In countries where CSF is endemic in domestic pigs it is common practice to

adopt systematic vaccination campaigns (Moennig 2000; Van Oirschot 2003), accompanied

by routine diagnostic procedures and control measures (Van Oirschot 2003) to minimise

serious losses of pigs from the disease (Moennig 2000). In areas with a high level of

endemicity, routine vaccination is the most common means used for prevention and control

of the disease (Suradhat et al. 2007). Vaccination overcomes some of the ethical dilemmas

arising from large-scale culling of pigs during an outbreak (Klinkenberg et al. 2003).

Moreover, CSF can be effectively controlled by vaccination with the live C-strain vaccine

(Kortekaas et al. 2010), and pigs can be protected against infection for at least 10 months

following oral vaccination with ‘C-strain’ live virus vaccine (Kaden and Lange 2001). An

efficient surveillance system must be an integral part of any control strategy (Moennig

2000).

Oral vaccination of wild boar may contribute to lowering the incidence of CSF, and

consequently diminishing the threat of the introduction of virus to domestic herds. Disease-

free countries should not vaccinate pigs against the disease but they should be aware of the

disease and have a rapid response plan to counter any incursions. Once CSF is introduced

into areas with a high pig density, an emergency vaccination program should be

immediately instituted, to be of maximal benefit (Van Oirschot 2003).

Control of animal-to-animal transmission of disease agents is a key concept in

infectious disease epidemiology; however, identifying the types of contact that lead to

transmission should be undertaken first. To reduce disease transmission in animals and

23

livestock, movement controls are needed to be strictly implemented and subject to

legislation (Fevre et al. 2006).

However, control of CSF remains challenging in many regions, and it is likely that

the disease will remain endemic in South-East Asia for many years to come. Factors

underlying the lack of success in disease control include a lack of funds to adopt a

comprehensive vaccination program, and, in some countries, limited expertise and

diagnostic facilities (Suradhat et al. 2007). The status control measures adopted or applied

in different countries in South East Asia are presented in Table 1.3.

Table 1.3 Status and control measures adopted/applied in South East Asia

Country Status of CSFV Control measures applied/adopted

Indonesia

Korea

Malaysia

Mongolia

Myanmar

Philippines

Taiwan

Thailand

Vietnam

Outbreaks of CSF still occur regularly, officially notifiable except for Indonesia.

- Movement control

- Eradication plan in most countries except Mongolia, Myanmar, Philippines, and Vietnam.

- Combination of slaughter and vaccination (Korea, Mongolia, Taiwan, Thailand, and Vietnam)

- Vaccination only (Indonesia, Malaysia, and Philippines).

Sources: Blome et al. (2010); Edwards et al. (2000); Fritzemeier et al. (2000).

1.7 Economic Impacts

The largest direct economic impact of CSF is through reduced production.

Morbidity and mortality directly impact upon the farmers’ financial viability and can also

24

influence the marketing of pork and its price (Rendleman and Spinelli 1999). The economic

impact of the disease depends upon the response strategies adopted by farmers and any

possible market effects. The impact can be mitigated if the farmers’ income source is

diversified or if there are other opportunities to generate income (Le Gall, 2006). The

disease may affect the whole national economy when a serious outbreak happens. For

example, an outbreak of CSF in the Netherlands in 1997-98 led to the death or slaughter of

approximately 12 million pigs as part of the eradication campaign. The cost of this outbreak

was estimated to be US$2.5-3 billion, half of which was public money and half was shared

equally between farmers and other participants in the livestock production chain (FAO

2002). The effects of the epidemic were so severe that the Government of the Netherlands

approved a national pig restructuring plan that resulted in a reduction of the national pig

herd by approximately 25% within two years (FAO 2002). In Indonesia, estimates of

300,000 to 400,000 pig mortalities from a total population of approximately one million

pigs were reported in Bali alone when the disease was first introduced in October 1995. In

addition, the pig population was estimated to have decreased by 45 and 23% respectively in

Kabupaten Kupang and Belu in West Timor (Christie 2007). In these districts up to 80%

mortality was reported in some herds (Christie 2007; Satya 2009).

The disease may result in bans on the export of products and subsequently may

impact upon the market price of pigs (Bech-Nielsen et al. 1993). The economic impact of

current control strategies is mainly associated with transport standstill measures (45% of all

costs). Of three control strategies in free areas (detecting and stamping-out affected herds;

strategies not based on vaccination; and emergency vaccination), not adopting vaccinating

has the potential to minimise the costs for controlling the disease (Saatkamp et al. 2000).

25

1.8 Diagnosis

1.8.1 Clinical diagnosis

It is difficult to make a clinical diagnosis of CSF, especially in older pigs (Paton and

Greiser-Wilke 2003), because of the presence of viral strains with only moderate virulence

(Koenen et al. 1996; Williams and Matthews 1988). This increases the danger of delayed

detection of primary cases, as was experienced in England in 2000 (Paton 2002). Although

the diagnosis of CSF can be based on clinical and pathological findings (Edwards 2000),

the clinical signs are often not pathognomonic for the disease. The disease often has an

incubation period of some weeks, requiring several cycles of amplification before it

becomes clinically apparent (Paton and Greiser-Wilke 2003). Furthermore the recent

emergence of porcine dermatitis and nephropathy syndrome also complicates the diagnosis,

since it can have a similar clinical appearance to CSF therefore, confirmation of disease has

to be supported by laboratory investigations (Edwards 2000), even for secondary cases

during large outbreaks (Paton and Greiser-Wilke 2003).

1.8.2 Laboratory Tests

Laboratory tests are used to confirm the diagnosis of CSF and either detect viral

antigen or antibody to the virus. A fluorescent antibody test (FAT) using polyclonal

antibody is widely used in laboratories for the detection and identification of antigen in

cryostat sections. Monoclonal antibodies are used in only a few countries, mainly for

specialist purposes rather than for routine investigations (Edwards et al., 2000). Some

countries have adopted an antigen enzyme-linked immunosorbent assay (ELISA), where

different types of ELISA techniques (competitive, blocking, indirect) and different ELISA

kits are used for the diagnosis of infection. Reverse transcription polymerase chain reaction

26

(RT-PCR) has been used for the differentiation of CSFV from ruminant pestiviruses (Canal

et al. 1996). The fluorescent antibody virus neutralization (FAVN) test and the

neutralization peroxidase-linked assay (NPLA) have limited use because of the need for

cell culture facilities (Edwards et al. 2000). A PCR has been used to determine the

relatedness between Colombian isolates from different geographical regions, and genetic

sequences of the glycoprotein E2 and the 5_UTR of CSFV (Sabogal et al. 2006).

Moreover, a multiplex RT-PCR assay has also been used for the rapid and differential

diagnosis of CSF from other pestiviruses (de Arce et al. 2005).

Serology is routinely used for the diagnosis of the disease and also for surveillance.

Serology is the method of choice for surveillance of CSF in an apparently disease-free area

or for insuring that there are no residual foci of infection during an eradication program

(Pearson 1992).

Antibodies are first detectable 2 to 3 weeks after infection, persist in surviving

animals for the duration of their life (Moennig and Greiser-Wilke 2008) and are a good

indicator that infection with CSFV has been present in a pig herd. The most commonly

used tests for antibody detection are virus neutralization tests (VNT) and ELISAs. The

VNT is regarded as the “gold standard” but it is labour intensive and time consuming, as it

relies on cell culture technology (Dahle et al. 1993; Dekker et al. 1995).

Three ELISA test procedures have been described for detecting antibody to CSFV: an

indirect ELISA (Moennig et al. 1990); a blocking ELISA (Leforban et al. 1990); and a

competitive ELISA (Clavijo et al. 2001; Makarananda and Gordon 1992). The sensitivity

and specificity of the ELISA tests have been reported to be greater than the FAVN test and

the NPLA (Leforban et al. 1990; Moennig et al. 1990). All ELISA tests offer the

advantages that they can be performed within 24hr. However imperfect tests can lead to

27

misclassification of the disease status of pigs (Greiner and Gardner 2000), and details of the

sensitivity (Se) and specificity (Sp) of the ELISAs is summarised in Table 1.4.

Table 1.4 Sensitivity and specificity of ELISA's used to detect CSF

Type of ELISA Sensitivity Specificity References

Indirect ELISA

Ceditest ELISA for CSFV-Ab using monoclonal antibody ELISA using glycosylated E2

99%a;98.3%b;

96.1%c; 98%e

99%a; 99.6%b;

94.8%c;>99%d,e

a. Colijn et al. (1997)

b.Moseret al.(1996)

c.Sunget al. (2010)

d.Moormannet al. (2000);

e.Loeffenet al. (2009)

Blocking ELISA

96.9%(cut off value 50%) f

96.9%(cut off value 30%)f

95.2%–98.9%g,h

97.5%i

97.8%, (cut off value 50%) f

97.3%(cut off value 30%) f

97.8%–99.5%g,h

99.5%i

f.Beaudeauet al. (2001)

g.Vicenteet al. 2005)

h.Ruiz-Fons et al (2006)

i.Zupancicet al. (2002)

Competitive ELISA 86%j 100%j j. Clavijo et al. (2001)

28

1.8.3 Differential diagnosis of CSF

In the field CSF is often suspected initially on clinical signs and gross

pathological lesions (AusVetPlan 2009; Greiser-Wilke et al. 2007). However many clinical

signs are not exclusively associated with CSF and the signs can vary with the strain of

virus, age and health status of the pigs (Greiser-Wilke et al. 2007) and presence of

concurrent infections (AusVetPlan 2009). Diseases with similar clinical signs to CSF which

should be included in a differential diagnostic list include: Porcine Circovirus type 2,

African Swine Fever, erysipelas, infection with Haemophilus parasuis, Streptococcus suis,

Menangle virus or porcine myocarditis virus, Actinobacillus pleuropneumonia,

Pasteurellosis, BVD, salt poisoning (water deprivation), Aujeszky’s disease, salmonellosis

and Viralencephalomyelitis (Andries and Pensaert 1980; Asai et al. 2010; AusVetPlan

2009; Balatinec et al. 2010; Dixon and Chapman 2008; Gard et al. 2007; Qiu et al. 2008;

Wilkinson et al. 1981).

1.9 Study aims

The aim of this study was to investigate the distribution of CSF and risk factors for

infection in eight selected villages from two Districts in West Timor, in the province of

Nusa Tenggara Timor (NTT) in eastern Indonesia. The information obtained from the study

will contribute to a greater understanding of CSF in this region and provide information to

support decision-making by local government officials and the industry about control of

CSF in the province.

29

1.10 Study objectives

The principle objective of the study was: to estimate the seroprevalence of CSF in

pigs from eight selected villages of West Timor.

The secondary objectives of the study were:

To describe the pig management and trading practices adopted by pig farmers in

West Timor.

To investigate the association between seropositivity and individual and herd factors

with the aim of identifying risk factors associated with seropositivity.

1.11 Hypothesis

The hypothesis of this thesis is that CSF is present in West Timor, and the infection

results in morbidity and mortality in pig herds. It is proposed that differences exist in the

proportion of seropositive pigs in herds and villages and these differences can be attributed

to particular management and husbandry practices adopted by farmers.

In the following chapter the materials and methods used in this study are outlined.

30

Chapter Two

Materials and Methods

2.1 Introduction

East Nusa Tenggara (Indonesian: Nusa Tenggara Timur - NTT) is a province of

Indonesia, located in the eastern part of the Lesser Sunda Islands. The province consists of

566 islands, but is dominated by the three main islands of Flores, Sumba, and Timor

(Provincial Government of NTT 2010). Timor is an island at the southern end of Maritime

Southeast Asia, north of the Timor Sea. It is divided into the independent country of the

Republic of Democratic Timor Leste, and West Timor which is part of the Indonesian

province of NTT with Kupang as its capital. West Timor is split into five regencies

(districts); from west to east the five regencies are: Kupang district, Kupang city, Timor-

Tengah Selatan (South Central Timor), Timor-Tengah Utara (North Central Timor) and

Belu (See Figure 2.1). The economy in West Timor is mainly agricultural, with the

livestock sector playing an important role in the economy of families (Provincial

Government of NTT 2010).

Data were collected from two districts in West Timor during the period of April

2010 to May 2010. This region was selected because of two main reasons: Firstly, West

Timor has a high pig population of 549,978 (Provincial Livestock Services of NTT 2010),

which is 39% of the total pig population in the province of NTT. Secondly, in line with the

increase in the pig population, CSF has also increased and been clinically found in pigs in

West Timor and potentially can cause significant economic losses to farmers through

reduced productivity and mortalities.

31

This study was designed to provide information to the local government and to the

livestock industries to enable the planning of suitable control and eradication programs for

CSF.

2.2 Existing Data Collection

Existing data (the number of pig owning households and the number of pigs owned

by those households) were collected from the Dinas Peternakan (livestock services) and

Bureau of Statistic Center of NTT. Informal meetings were conducted with the heads of 8

villages in March 2010 in the two selected districts of Kupang and Belu. At these meetings

the purpose of the study was explained. Additional data about the number of households

owning pigs and the number of pigs owned by farmers were also provided by local

veterinarians and veterinary assistants. However, most of the data were not current and did

not exist in the village offices, consequently most data were subsequently gathered directly

from the pig-owning households through the use of a structured questionnaire.

2.3 Study Design

2.3.1 Study type

A standard cross-sectional study was conducted in two of the four districts of

Timor. This type of study, which is commonly used in epidemiology, is often adopted to

obtain information about baseline characteristics of a population (Pfeiffer 2010), and is

usually designed to select a random sample of the target population (Thrusfield 2005). The

external population was the total pig population in West Timor with the pig population in

the two selected districts being the target population. Pigs in the eight selected villages

were the study population, and the unit of interest was the individual pig.

32

2.3.2 Sampling method

A multi-staged sampling approach was used to select the districts, sub-districts,

villages, pig owners and pigs in this study. According to Pfeiffer (2010) multistage

sampling extends cluster sampling by using random sampling at different hierarchical

levels of aggregation of the sample units. A key advantage of multistage sampling is that it

can be used if no sampling frame is available for the sample units. Inclusion and exclusion

criteria used for the sampling are outlined in Table 2.1.

Table 2.1 Inclusion and exclusion criterian for selection of animals

Site Inclusion Exclusion

District Expected CSF status known –

based on reporting of clinical

disease to Dinas.

Unknown CSF status - based on no or

unreliable reporting of clinical

disease to Dinas

Sub-district Accessible

No security concerns – known to

be safe for research team to visit

Co-operation expected from sub-

district officials

People are not co-operative

Remote area

Security concerns

Village Co-operation expected People are not co-operative

Pig owner Present on day of visit

Gives consent to participate

Currently has at least one pig over

the age of 3 months in their pig

herd

Individual

pig

Known to belong to the

interviewee

Over 3 months of age

Less than 3 months of age

33

2.3.3 Sampling Steps.

2.3.3.1 Step 1-Selection of Districts

Two districts were selected in West Timor (Figure 2.1). The selection of districts

was purposive giving consideration to three main factors (Table 2.2), specifically: CSF

status based on reported clinical cases, geographical diversity, and importance in terms of

pig production and trading.

Table 2.2 Factors considered when selecting districts

Names of selected Districts Justification for selection

Belu, Kota Kupang • Both have a history of reported cases of CSF

• Belu is the district that borders East Timor and pig

trading occurs across the border with Timor Leste

• Kota Kupang is the main pig production district in West

Timor and includes the provincial capital of Kupang.

34

Figure 2.1 Selected districts (kabupaten) in West Timor coloured as yellow (Belu and Kota Kupang). S=sampled districts, N=not sampled districts

2.3.3.2 Step 2 - Selection of Sub-districts

Sub-districts were selected using simple random sampling after exclusion of sub-

districts that were remote or considered to be unsafe or not co-operative. A random number

generator in Excel was used to select two sub-districts (Maulafa and Oebobo) from the five

sub-districts in the district of Kota Kupang and another two (Atambua Selatan and Tasifeto

Barat) from 25 in the district of Belu (Figure 2.2). The decision to include two sub-districts

per district was based on logistical considerations given the time and funds available for the

collection and processing of samples.

35

Figure 2.2 Selected sub-districts (kecamatan) in the districts of Kota Kupang (Oebobo and Maulafa) and Belu (Tasifeto Barat and Kota Atambua) coloured as yellow. S=sampled sub-districts, N=not sampled sub-districts

2.3.3.3 Step 3 - Selection of Villages

For each selected sub-district, two villages were selected from a sampling frame

(eight villages in the Sub-district Maulafa and 14 villages in the Sub-district Oebobo from

the district of Kota Kupang and four villages in the Sub-district Atambua Selatan and eight

villages in Tasifeto Barat in the district of Belu) after exclusion of villages considered not

to be co-operative. A random number generator in Excel was used to select the two villages

from each of the four selected sub-districts. The villages selected were Sikumana and

Oepura from Maulafa, Oebobo and Oebufu from Oebobo (Figure 2.3), Fatukbot and Lidak

from Atambua Selatan and Naitimu and Naekasa from Tasifeto Barat (Figure 2.4).

36

Figure 2.3 Selected villages (kelurahan/desa) in the sub-districs of Maulafa (Sikumana and Oepura) and Oebobo (Oebobo and Oebufu) in the district of Kota Kupang. S=sampled villages, N=not sampled villages

2.3.3.4 Step 4 - Selection of pig owners

From each selected village, a list of pig owners in the village was obtained from the

head of the village. Random selection with replacement was used to determine which pig

owners would be invited to participate in the survey on the day of visit. The village head

was advised ahead of the date of visit of the list of pig owners selected to participate in the

survey.

37

Figure 2.4 Selected villages (kelurahan/desa in the sub-districts of Tasifeto Barat (Naitimu and Naekasa) and Atambua Selatan (Fatukbot and Lidak) in the district of Belu. S=sampled villages, N=not sampled villages

A selected pig owner who did not meet the selection criteria (Table 2.1) was

replaced with another randomly selected pig owner. The list of randomly selected pig

farmers for a village included 20% more farmers than initially needed in order to ensure a

sufficient number of eligible farmers were available to participate on the sampling day. The

pig owners from each selected village were randomly selected using a simple random

sampling technique. Each pig owner had the same probability of being selected after

inclusion of pig owners present on the day of visit, who gave consent to participate, and had

at least one pig in their herd that was over the age of 3 months.

38

2.3.3.5 Step 5 - Selection of pigs

From each interviewed farmer, pigs were randomly selected for collection of a

blood sample from the list of pigs older than 3 months of age owned by the farmer on the

day of visit. Blood samples were taken from both sick and healthy pigs and from both

previously vaccinated and non-vaccinated pigs. Individual pigs that met the selection

criteria were selected using simple random sampling with all pigs having the same

probability of selection.

2.3.4 Seroprevalence and Risk Factor Surveys

2.3.4.1 Prevalence survey

A total of 90 pigs were sampled from each of the eight selected villages. Blood

samples were collected from either the jugular and/or auricular veins. Approximately five

ml of blood was collected using vacutainers or a 23 gauge needle and a 5 ml syringe. Sera

were allowed to stand at room temperature for 1 hour with tubes in an upright position until

the sera had separated from the clot. The clot was removed using sterile rods after the tubes

had been stored at 4°C for 12 hours. The sera were removed with sterile pipettes and

deposited in fresh tubes or if necessary the sample was centrifuged for 15 minutes at 2000

rpm at the local livestock services laboratories. Sera were then frozen and stored at -20°C.

After all samples had been collected, sera were sent to the Animal Biomedical and

Molecular Biology Laboratory, Udayana University, Denpasar for testing for the presence

of antibody to CSF by using an ELISA test. Collection of the samples had been approved

by the Murdoch University Animal Ethics Committee.

39

2.3.4.2 Risk Factor Survey

This study was undertaken in both urban and rural areas of West Timor.

Questionnaires were distributed to farmers in order to identify possible risk factors

associated with CSF infection (Appendix 1). The questionnaire was administered to 30

farmers from each sampled village. The questionnaire had been approved by the Murdoch

University Human Ethics Committee.

The questionnaire included closed, open and ranking questions. The questionnaire

consisted of seven sections which collected information about the farm structure and herd

information, reproductive management and performance, husbandry, pig introductions and

exits, health status, farmer’ knowledge and history of vaccination. The questionnaire was

conducted to study and identify whether these factors were associated with the presence of

CSFV infection in West Timor.

The questionnaire was initially developed in English and then translated into

Indonesian prior to implementation. The questionnaire was developed and modified slightly

following discussion with local veterinary staff from the Provincial Dinas Peternakan

(Livestock Services) NTT. The questionnaire and form for recording pig information was

then pretrialed on one group of 12 pig farmers from Kupang. Based on the responses from

these farmers slight modifications were made to the questionnaire. The final questionnaire

was administered to selected pig owners through the use of face-to-face interviews. The

questionnaire interviews were conducted with the assistance of local staff from the local

dinas who could provide information in the range of local languages as well as Bahasa

Indonesia. Prior to conducting an interview the purpose of the survey was explained to the

owner. The interview was completed in full before blood samples were collected from pigs

40

owned by the farmer. The detailed protocol for undertaking the farmer interviews is

provided in Appendix 1.

2.4 Laboratory methods

Sera were tested at the laboratory using the commercially available

PrioCHECK®CSFV AB (Prionics, Lelystadt, Netherlands) ELISA. The procedure

recommended by the manufacturer of the test was followed for the testing process (see

Chapter 3).

2.5 Data management

A purpose built database was designed in EpiInfoTM version 3.5.1 for the entry and

storage of data from the farmer questionnaire and the pig-recording sheet. For subsequent

analyses, data were exported to Excel 2007 (Microsoft). In Excel 2007, data were

categorized as categorical and continuous variables depending on their type. The data then

were exported to SPSS statistics version 17.0 for subsequent statistical analysis.

2.6 Data Analyses

2.6.1 Univariable analysis

Data were analyzed based on their type (categorical or continuous). In the

descriptive study (Chapter Three), frequency distributions were performed for categorical

variables, while means, maximums, and minimums were calculated for continuous

variables.

In the serological study (Chapter Four), the seroprevalence was compared between

pigs from different villages, sub-districts, and districts. Odds ratios (OR) and their 95%

confidence intervals were calculated using Woolf’s method (Kahn and Sempos 1989). The

41

seroprevalence and their 95% confidence intervals (95% CI) were calculated using the

exact binomial method (Ross 2003). Statistical investigations were undertaken with the

Chi-Square tests for independence to determine differences in prevalence between villages,

sub-districts and districts. A p-value less than 0.05 was taken as evidence of significant

difference.

A one way ANOVA test was performed for continuous variables to compare the

mean for each variable for seropositive and seronegative animals.

2.6.2 Multivariable analysis

Risk factors with a significance value P < 0.25 were subject to further analysis using

multivariable logistic regression test with SPSS package (version 17.0). The process and

interpretation of the multivariable logistic regression model are outlined in Chapter Five.

42

CHAPTER THREE

PIG HUSBANDRY AND MANAGEMENT

3.1 Introduction

The husbandry and management of pigs can have a significant impact on the entry,

presence and severity of disease. The study reported in this chapter outlines the routine

husbandry and management practices adopted by pig farmers in West Timor. It also

describes the regular movement of pigs, their health status and vaccinations that are

commonly practiced in this region. Pigs are important to the community of West Timor and

have both financial and traditional values. Furthermore pigs are a source of accumulated

wealth (act as a bank) and act as a cash reserve to meet current and future household needs.

Therefore the loss of pigs from CSF or other diseases can have severe direct economic

consequences for individual farmers, as well as requiring a significant input (expenditure)

from the local government for disease control measures.

The objectives of this study were to obtain baseline information on: herd

characteristics (size, structure, age, breeds, proximity to neighbouring farms), herd

management (husbandry, diet, care of sick animals, disposal of dead pigs, breeding

program, exposure to other pigs, water source) and herd health history (vaccination status,

history of pigs in herd showing clinical signs consistent with CSF).

43

3.2 Materials and Methods

3.2.1 Study area

This study was undertaken in both urban and rural areas of West Timor. The

Indonesian component of the island of Timor (West Timor) has a land area of 15,850 km².

On Timor there are two seasons: a wet/rainy season and a dry season. The wet season

extends from October until April; however, rain comes at varying intensities during this

time. Intensive or heavy rain only lasts for two to three months of the year. During the dry

season, the weather is very hot and humid, particularly in the city of Kupang. The average

temperature in Kupang is 27.1°C (81°F) with the highest monthly temperature of an average

33°C (91oF) recorded from September until November. The lowest monthly temperature is

21°C (70°F) in July and August. The average annual rainfall is 1441 mm (56.7 in), which

equates with 120 mm (4.7 in) per month (www.climatetemp.info accessed 20th July 2010).

The highest monthly rainfall (469.8 mm) occurs in February and the lowest (18 mm) in

April (Statistics of Kota Kupang 2010).

3.2.2 Questionnaire design and implementation

A questionnaire was designed as outlined in Chapter 2. The questionnaires were

administered to selected pig owners through the use of face-to-face interviews (Figure 3.1).

The detailed protocol for undertaking the farmer interviews is provided in Appendix 1. All

questionnaires were administered by the author.

44

Figure 3.1 Face to face farmer interview in the district of Belu

3.2.3 Existing data collection

Data were also collected on disease information, pig population, number of pig-

owning households, and maps of the Districts from a range of sources, specifically the

Dinas Peternakan NTT (data about pig households and pig disease), Central Bureau of

Statistics (data on sub-districts and villages in West Timor), and from village offices (data

of pig households and pig numbers from the Head of Villages) as outlined in Chapter 2. An

informal meeting was held with local veterinarians and veterinary assistants from the

Provincial Dinas and District Dinas of Kota Kupang and Belu, to ensure that the members

involved in the sampling had a clear understanding of the survey purpose. Informal

meetings with the head of the selected villages were conducted in March 2010 when the

purpose of the survey was explained, permission obtained to conduct the survey in their

village and data gathered on the number of households present.

45

3.2.4 Questionnaire interviews

At each village, questionnaires were conducted at the selected pig farmer's house.

Before the interviews started, the visiting team was introduced and the objectives of the

project were explained. Participants were asked about livestock problems and were

provided with general information about CSF. They were informed that the disease is

infectious and contagious and cannot be treated directly, but can be prevented by

vaccination and good management practices.

3.2.5 Data analysis

All data were entered into Epi Info™ (version 3.5.1) and subsequently analysed with

SPSS (version 17.0) as outlined in Chapter 2. Frequency functions were calculated for all

variables measured.

3.3 Results

3.3.1 Pig population in West Timor

The population of pigs in the 5 districts in West Timor is presented in Table 3.1

(Dinas Peternakan - Livestock Services of NTT, 2009). The highest population of pigs was

in the district of Timor Tengah Selatan (South Central Timor - TTS), and the lowest

population in the district of Timor Tengah Utara (North Central Timor - TTU). The

selected districts are characterized as follow: Kupang is the entry point of pigs from

Surabaya and Bali, and Belu is in the border region with Timor Leste and therefore there is

significant trading and movement of pigs in these two districts.

46

Table 3.1 Pig population in West Timor

Districts Pig population Kupang 111,854 Kota Kupang 23, 350 Timor Tengah Selatan 294, 856 Timor Tengah Utara 70,584 Belu 116,010 Total 616,654 Source: Dinas Peternakan Provinsi NTT (2009) 3.3.2 Survey Results

Table 3.2 Frequency of husbandry and management practices adopted by pig farmers in West Timor.

Variables Number of households

Percentage

Never attended school

Completed Primary School

Completed Junior High School

Completed Senior High School

Graduated from university

8

39

38

146

9

3.3

16.3

15.8

60.8

3.8

Attended animal training

Never attended animal training

1

239

0.4

99.6

Raising pigs is their main occupation

Raising pigs is not their main occupation

0

240

0.0

100

47

Variables Number of households

Percentage

Main occupation:

– Civil servant/army/police

– Agricultural farmer

– Carpenter

– Retired

– Missionary

– Driver

– Entrepreneur

137

8

1

90

1

2

1

57.1

3.3

0.4

37.5

0.4

0.8

0.4

Pig raising system:

– Traditional

– Semi-intensive

239

1

99.6

0.4

Purpose for keeping pigs:

– For consumption by their family

– Paying for school fees

– For emergency needs

– For traditional and religious ceremonies

23

21

191

2

9.6

8.8

80.8

0.8

Pig raising type:

– Fattening

– Breeding

– Fattening and breeding

63

76

101

26.3

31.7

42.0

48

Variables Number of households

Percentage

Pigs were kept in pens

Pigs were tied up

Pigs were free to roam

238

1

1

99.2

0.4

0.4

Roof of pen made from tin

Roof of pen made from palm leaves

189

51

78.8

21.2

Wall of pen was fully bricked

Wall of pen was half brick and half open

Wall of pen made from wood/bamboo

1

67

172

0.4

27.9

71.7

Floor of pen was dirt

Floor of pen made of concrete

Floor of pen made of wood/bamboo

Floor of pen was slatted wooden/bamboo floor

19

200

10

11

7.9

83.3

4.2

4.6

Pig pens cleaned

Pig pens not cleaned

186

54

77.5

22.5

Pig pens cleaned once daily

Pig pens cleaned twice daily

Pig pens cleaned once weekly

Pig pens cleaned less frequently

179

2

4

1

96.2

1.1

2.2

0.5

Water used to clean the pig pens

Water not used to clean the pig pens

186

0

100

0

49

Variables Number of households

Percentage

Provide soap/disinfectant for cleaning feet and hands of

workers and visitors

Did not provide soap/disinfectant for cleaning feet/hands of

workers and visitors

0

240

0

100

Provide overalls for visitors

Did not provide overalls for visitors

0

240

0

100

Limit vehicles entering the farm

No limit on vehicles entering the farm

0

240

0

100

Pigs washed

Pigs not washed

140

100

58.3

41.7

Pigs washed once daily

Pigs washed twice daily

Pigs washed once weekly

Pigs washed occasionally

136

2

1

1

97.2

1.4

0.7

0.7

Pigs looked after in the morning only

Pigs looked after in the afternoon only

Pigs looked after in the morning and afternoon

4

2

134

1.7

0.8

97.5

Spend 30 minutes a day to look after the pigs

Spend 60 minutes a day to look after the pigs

217

23

90.4

9.6

50

Variables Number of households

Percentage

Source of drinking water for pigs

Local stream/river

Tap water

Well

10

221

9

4.2

92.0

3.8

Pigs fed once daily

Pigs fed twice daily

Pigs fed three times daily

1

220

19

0.4

91.7

7.9

Swill fed to pigs

Agricultural products fed to pigs

Mixed feed (including swill) fed to pigs

219

15

6

91.3

6.3

2.5

Swill cooked before fed to pigs

Swill not cooked before fed to pigs

139

80

63.5

36.5

Swill cooked for at least 90 minutes

Unsure of length of time swill cooked

41

35

2.9

97.1

Individual pigs identified

Individual pigs not identified

0

240

0

100

Used artificial insemination

Used natural mating

32

85

27.4

72.6

Used own boar for natural mating

Used borrowed boar from same village for mating

Used borrowed boar from outside village for mating

35

47

1

42.9

56.0

1.1

51

Variables Number of households

Percentage

Pigs introduced into the herd in the last 12 months

Did not introduce pigs into the herd in last 12 months

29

211

12.1

87.9

Introduced pig given as a gift by a family member/relative

Introduced pig purchased

1

28

3.4

96.6

Origin of introduced pig(s) in the last 12 months

Another farm, same village

Another village, same sub-district

Another village, different sub-district, same district

Another district

16

4

3

6

55.2

13.8

10.3

20.7

New pigs acquired for raising (fattening)

New pigs (boar) acquired for breeding

26

3

89.7

10.3

Buy pigs from markets

Buy pigs from other farmers

7

21

25.0

75.0

Origin of the pig bought was from inside the village

Origin of the pig bought was from outside the village

23

5

82.1

17.9

Has sold pigs in the last 12 months

Did not sell pigs in the last 12 months

8

232

3.3

96.7

Sell pigs to people living in their village

Sell pigs to people outside the village but in the same district

Sell pigs to people who live outside the district

4

3

1

50.0

37.5

12.5

52

Variables Number of households

Percentage

Pigs sold to other farmers

Pigs sold to brokers/vendor

Pigs were given away/sold to family/relatives

Pigs sold to restaurant owner

1

1

5

1

12.5

12.5

62.5

12.5

Likely to sell pigs for money

Very likely to sell pigs for money

2

238

0.8

99.2

Very unlikely to sell a sick pig

Unlikely to sell a sick pig

Likely to sell a sick pig

75

164

1

31.3

68.3

0.4

Very unlikely to sell an old pig

Unlikely to sell an old pig

Likely to sell an old pig

Very likely to sell an old pig

1

1

12

225

0.4

0.4

5.4

93.8

Likely to sell pigs in January

Unlikely to sell pigs in January

0

240

0

100

Likely to sell pigs in February

Unlikely to sell pigs in February

0

240

0

100

Likely to sell pigs in March

Unlikely to sell pigs in March

0

240

0

100

Likely to sell pigs in April

Unlikely to sell pigs in April

1

239

0.4

99.6

53

Variables Number of households

Percentage

Likely to sell pigs in May

Unlikely to sell pigs in May

0

240

0.0

100

Likely to sell pigs in June

Unlikely to sell pigs in June

1

239

0.4

99.6

Likely to sell pigs in July

Unlikely to sell pigs in July

188

52

78.3

21.7

Likely to sell pigs in August

Unlikely to sell pigs in August

191

49

79.6

20.4

Likely to sell pigs in September

Unlikely to sell pigs in September

2

238

0.8

99.2

Likely to sell pigs in October

Unlikely to sell pigs in October

0

240

0

100

Likely to sell pigs in November

Unlikely to sell pigs in November

79

161

32.9

67.1

Likely to sell pigs in December

Unlikely to sell pigs in December

85

155

64.6

35.4

Reason for selling pigs in selected months:

- Buyers looking for pigs

- Pig is large enough to sell

- To pay for school fees

- For emergency needs

42

1

167

30

17.5

0.4

69.6

12.5

54

Variables Number of households

Percentage

Reason for less likely to sell pigs in selected months:

- Few buyers looking for pigs

- Few buyers and no emergency needs

- No emergency needs

51

169

20

21.3

70.4

8.3

Slaughters pigs at home 0 0

Pigs sold from home (buyer comes to the home)

Pig sold to a market

222

17

92.9

7.1

Had a sick or dead pig in the last 3 months

Didn’t have a sick or dead pig in the last 3 months

24

215

10.0

90.0

Gender of sick pig:

- Female

- Male

- Castrated male

5

16

3

20.8

66.7

12.5

Clinical signs observed in the sick pig:

- Loss of appetite

- Pyrexia and lethargy

15

9

62.5

37.5

Action taken when pig became sick:

- Nothing

- Gave natural medicine

- Contacted veterinarian or veterinary assistant

- Purchased medicines and treated themselves

3

19

1

1

12.5

79.2

4.2

4.2

55

Variables Number of households

Percentage

A sick pig had died in the last 3 months

Didn’t have a sick pig die in the last 3 months

24

216

10.0

90.0

What would you do with any sick pigs?

- Nothing

- Treat with own medicine

- Sell at the market

171

34

35

71.3

14.2

14.5

What would you do with the body of a dead pig?

- Burn

- Bury

- Eat

- Throw away

1

219

12

8

0.4

91.3

5.0

3.3

- Usually bury a pig that dies suddenly

- Usually eat a pig that dies suddenly

238

2

99.2

0.8

Heard of other people in the village with sick pigs in the last

3 months

Hadn’t heard of other people in the village with sick pigs in

the last 3 months

0

240

0

100

Pig has contact with pigs owned by other farmers

Pig does not have contact with pigs owned by other farmers

0

240

0

100

The majority of pigs are skinny

The majority of pigs are average condition (not skinny or fat)

The majority of pigs are fat

92

145

3

38.3

60.4

1.3

56

Variables Number of households

Percentage

Farmer had heard about CSF

Farmer had not heard about CSF

8

232

3.3

96.7

Knew about CSF from a friend

Knew about CSF from TV, radio or newspapers

6

2

75.0

25.0

Pigs vaccinated against CSF

Pigs not vaccinated against CSF

13

227

5.4

94.6

Reason for not vaccinating the pigs?

- Does not believe in vaccination

- Not home when the vaccinator came

- Use natural medicines instead

1

6

220

0.4

2.6

96.9

Why were pigs vaccinated?

- The veterinarian came and vaccinated my pigs

- Wanted pigs to be healthy

5

8

38.5

61.5

Pigs vaccinated once only

Pigs vaccinated each year

9

4

69.2

30.8

Body condition score of pigs

1

2

3

4

4

101

130

5

1.7

42.1

54.2

2.1

57

Table 3.3 Number of livestock owned by the interviewed households

Livestock species Number of

households

Number of livestock owned

Minimum Maximum Mean

Cattle 16 1 10 3.75

Goat 7 1 4 2.28

Pigs

< 3 months:

- Female

- Male

- Castrated male

3-6 months:

- Female

- Male

- Castrated male

6-12 months:

- Female

- Male

- Castrated male

> 12 months:

- Female

- Male

- Castrated male

4

2

13

75

83

99

38

26

5

31

19

22

1

4

1

1

1

1

1

1

1

1

1

1

4

5

5

10

10

8

6

3

2

8

2

20

2.50

4.50

1.38

1.50

1.85

1.57

1.50

1.26

1.40

1.83

1.10

2.27

58

Table 3.3 Number of livestock owned by the interviewed households ……continued

Livestock species Number of

households

Number of livestock owned

Minimum Maximum Mean

Number of pigs purchased in the last 12 months

29 1 5 1.27

Breed of pigs

Local breed

Cross breed

Landrace

24

216

4

1

1

1

6

15

48

2.54

2.47

22.50

Table 3.4 Litter sizes of pigs in interviewed households over the 12 month period preceding the survey

Number of households Minimum Maximum Mean

Sow

First parturition of the sow

- Litter size (first litter of that sow)

- Total number piglets born normal

- Total number piglets born abnormal

- Total number piglets born dead

- Total number of piglets weaned

Second parturition of the sow

- Litter size (second litter of that sow)

- Total number piglets born normal

- Total number piglets born abnormal

- Total number piglets born dead

- Total number of piglets weaned

10

10

0

8

10

1

1

0

1

1

5

5

2

1

12

12

2

10

12

12

7

10

12

12

2

10

8.6

8.6

4.1

5.3

12.0

12.0

2.0

10.0

59

3.3.2 Characteristics of pig-owning households and pig husbandry and management

practices adopted

3.3.2.1 Characteristics of pig-owning households

Most pig-owners (60.8%) had completed Senior High School (Table 3.1) with only

3.3% never having attended school. Only 0.4% of owners had received formal training on

animal husbandry/management. Pig-rearing was not the principal occupation of most of the

pig owners interviewed. The majority (57.1%) were civil servants, followed by retirees

(37%), agricultural farmers (3.3%), driver (0.8%), or carpenter, missionary and

entrepreneur (1% each).

3.3.2.2 Ownership of pigs and other animals

The majority of households (216/240 - 90%) kept crossbred pigs with an average of

2.47 (range 1 to 15) pigs per household (PHH). Twenty four households owned pigs of a

local breed with an average of 2.54 owned (range 1 to 6) and only 4 households owned

landrace pigs (average 22.5 owned, range 1 to 48). The gender and age of owned pigs is

summarised in Table 3.3. For pigs between the age of 3 and 6 months 41.25% of

households owned castrated male pigs (average 1.57), 34.6% owned entire males (average

1.85) and 31.25% owned female pigs (average 1.50 PHH). In contrast few households

owned castrated males between the age of 6 and 12 months (2.1%) compared with entire

males (10.8% 26/240) or females (15.8% 38/240). More households owned female pigs

older than 12 months of age (12.9% 31/240) than entire male pigs (7.9% 19/240) or

castrated males (9.2% 22/240).

Few households owned other types of livestock (Table 3.3) with only 16 households

owning cattle (average 3.75, range 1 to 10) and 7 owning goats (average 2.28, range 1 to 4).

60

3.3.2.3 Housing and system of pig raising in West Timor

In West Timor three main pig-raising systems are adopted (traditional, semi-

intensive and intensive). In the traditional system the pigs are either kept in pens, free to

roam or are tied up in the backyards of the farmers. In rural areas, the pens are usually

made up of bamboo or wood as these materials are widely available. In contrast in urban

areas some households have built permanent pens from concrete block construction with

concrete floors. In this survey nearly all households (99.6%) raised their pigs in the

traditional way and only one household (0.4 %) raised pigs semi-intensively. Most farmers

(99.2%) kept pigs in pens, one household (0.4%) kept their pigs tethered and one household

(0.4%) allowed their pigs to roam freely.

In this survey it was found that the roof, walls and floors of pens were made up of a

range of materials. The majority of the roofs (78.8%) were tin, and the remainder were

made from palm leaves. The majority of the pen walls (71.7%) were made of wood or

bamboo. Some walls (27.9%) were a half brick wall (open at the top), and only 1 (0.4%)

was a complete brick wall. Most pens had a concrete floor (83.3%). Other flooring included

dirt, wood or bamboo, and slatted bamboo or wooden floors with 7.9%, 4.2% and 4.6%

respectively. Most of the pig sheds were located near to the farmer’s house to enable easy

care and management of the pigs.

Of the 240 pig households 42% had a fattening and breeding style piggery, 31.7%

were breeding only and 26.3% fattening only. Most households spent time in the morning

and afternoon (97.5%) to look after their pigs and spent approximately 30 minutes each day

(90.4% HH) looking after their pigs.

61

3.3.2.4 Biosecurity

Pig-owning households, in general in West Timor, are not concerned about adopting

biosecurity measures, probably because of a lack of awareness of pig health, production

and disease transmission. Most farmers only own a few animals and these are usually kept

in pens which people, vehicles, other animals and insects can enter freely. In this survey no

households provided foot baths or cleaning materials for people entering pig pens and there

were no limitations placed on the entry of vehicles or people onto their farm. In contrast

most (77.5%) households cleaned their pig pens at least once a day, however the pens were

cleaned only with water and no disinfectants/detergents were used.

3.3.2.5 Feed and drinking water

The majority (91.7%) of farmers fed their pigs twice a day. A similar percentage

(93.8%) fed swill to their pigs with only 6.3% of households feeding them acommercial

feed (agricultural products-cassava root and leaves, banana steam and leaves, corn, tofu

waste, and coconut pulp). Swill was commonly cooked in a 20 litre tin (Figure 3.2).

Approximately two-thirds (65.8%) of households cooked the swill prior to feeding it to

their pigs, however most (85.4%) did not cook it for a set period of time.

62

Figure 3.2 Equipment used for cooking swill in a farmer's house in Kota Kupang

The main sources of drinking water for pigs in this study was from tap (drinking)

water (92%), a local stream (4.2%), or a well (3.8%). Most pigs were provided water in a

bucket however water was often provided ad libitum when pigs were fed.

3.3.2.6 Reproduction management

The majority (72.6%) of farmers used natural mating for reproduction purposes. Of

these farmers using natural mating, over half (56%) borrowed a boar from other farmers

from within their village, however 1.1% borrowed a boar from a farmer outside their

village.

Of 10 households with a maiden gilt that produced piglets in the year prior to this

questionnaire, an average of 8.6 piglets were born per litter (range 5 to 12) from this first

63

parturition. The average preweaning mortality was 4.1 (range 2 to 7) piglets for the first

litter. Only one household had a sow have a second litter in the year with 12 piglets born,

two of which died prior to weaning. No abnormal piglets (including still births, mummies

or deformities) were reported. The average number of piglets weaned was 5.3 (range 1 to

10) from the first litter and 10 from the second litter. Subsequent to weaning the piglets

were usually kept in a separate pen (Figure 3.3).

Figure 3.3 Weaner pigs in Belu

3.3.2.7 Body condition score

During the survey, it was found that the majority of the farmers (130/240 54.2%)

had pigs with a body condition score (BCS) 3, whereas other farmers (42.1%) had pigs with

BCS 2. The remaining pigs had a BCS of 5 (2.1%) and 4 (1.7%) had pigs with a BCS of 1.

64

3.3.2.8 Pig movement and trading

Of the 240 interviewed pig owners, 62.5% reported selling pigs to family members

or relatives. Some farmers sold to other farmers, to pig sellers not from a market, or to

restaurant owners (all 12.5%). The main reason for selling to a relative was that the buyer

knew about the pig (its presence, breed and performance). Most pig owners (50%) sold pigs

to relatives in the same village, with 37.5% selling to family members outside the village

but in the same sub-district, and only 12.5% sold to relatives living in villages located in

other districts. This is expected as typically families in West Timor live relatively closely in

one area of a village or sub-district. Only 12.1% of the interviewed farmers had acquired

new pigs in the 12 months preceding the survey. The majority (89.7%) of these farmers

purchased the pigs for fattening, although some were purchased as a new breeding boar for

their herd (10.3%). Most households acquiring new pigs (75.9%) purchased those pigs

directly from other farmers, although 24.1% did purchase them from markets.

3.3.2.9 Pig health status, CSF, treatment and prevention.

Nearly all interviewed households (96.7%) had never heard about or knew of CSF. Of

those who had heard of the disease, the source of information had primarily been friends

(75%), although some (25%) heard of it from television, radio or newspapers.

Although vaccination is the main strategy for preventing CSF in West Timor and is

provided free of charge by the government, most farmers (94.6%) had not vaccinated their

pigs. Vaccines were not used as farmers (96.9%) preferred natural medicines when they

had sick pigs, although some (2.7%) had not vaccinated their pigs as they were not at home

when the vaccinator came to their village. A few farmers (1%) did not believe in

vaccination. Most (61.5%) of those farmers who had their pigs vaccinated did so because

65

they wanted them to be healthy. The remaining 38.5% had their pigs vaccinated because the

veterinarians/vaccination team had come to their village and vaccinated their pigs. Most

owners (69.2%) of vaccinated pigs stated that their pigs had been vaccinated only once,

while 30.8% had their pigs vaccinated several times (although only once each year).

Ten percent of the pig owners had pigs that were sick in the preceding three months,

with most of these being entire males (66.7%), followed by females (20.8%), and castrated

males (12.5%). Clinical signs recognised by the farmers included loss of appetite (62.5% of

affected pigs) and pyrexia and lethargy (37.5%). All pigs that were sick died and all died

within one day of showing/developing clinical signs. When farmers had sick pigs they gave

them natural medicines (79.2%), while others (12.5%) did nothing. One person (0.4%) gave

medicines purchased from a dispensary/pharmacy, and another person contacted a

veterinarian/veterinary assistant. Nearly all farmers (91.3%) buried the body of any dead

pigs, however 5.0% reported they would eat the dead pig after cooking, 3.3% would throw

away the dead body, and only 0.4% would burn the body of the dead pig. If the pig had not

shown any signs of illness prior to death most households (77.5%) would eat the pig after

cooking it well.

3.4 Discussion

3.4.1 Pig households characteristics, farm structure and husbandry

In this survey it was found that most farmers raised their pigs in a traditional manner

in West Timor. This raising system is characterized by owning only a small number of pigs,

using local products for the pens and feeding locally available feed-stuffs including swill.

There are only a limited number of semi-intensive and intensive farms in West Timor and

these are characterized by a larger herd size, use of commercial feed, and the pigs are

restricted to pens which are cleaned regularly and which have automatic watering systems.

66

Most of the intensive pig farms also keep records of individual animals and use artificial

insemination (Craig et al. 2010).

The educational background of the pig farmers in West Timor varied widely,

although most (61.8%) had completed senior high school. Having a good educational

background, especially with respect to knowledge and skills for animal health and

production, can be beneficial in increasing the production of pigs and maintaining their

health and well-being. The educational standard of the owners must be considered in

extension programs to ensure that any material developed is suitable for the target audience

and it is delivered in a suitable manner. This is particularly important in West Timor to

increase the adoption of vaccination by farmers. In the UK, better-educated farmers are

known to make greater use of information, advice and training, to participate more in

government schemes and to be more proactive in adjusting to change and planning for the

future of their business (Gasson 1998).The raising of pigs was not the main occupation of

the households interviewed and is done during the farmers “spare-time”. This part-time

activity could result in them providing minimal inputs to their pigs which could impact on

the production and health of their animals and consequently the success of any disease

control program.

Two breeds of pigs are commonly raised by households in West Timor (local and

cross breed). Crossbreed pigs are more frequently owned which could be as a result of their

larger body size, faster growth rate and higher production resulting in a higher price at sale.

As well as pigs some households raised other livestock such as cattle and goats. Ownership

of cattle can be important as there can be transmission of Mucosal Disease (MD) virus to

pigs resulting in the presence of antibodies in pigs (Snowdon and French 1968). Two other

members of the pestiviruses genus, namely, bovine viral diarrhoea (BVD) virus and border

disease (BD) virus, can also infect pigs and consequently may interfere with the diagnosis

67

of CSF (de Smit et al. 1999b; Terpstra and Wensvoort 1988, 1997; Wensvoort et al. 1994).

Some authors reported that pestiviruses are able to cross species barriers with relative ease

and BVD virus naturally infects pigs, sheep, goats and a wide range of wild ruminants

(Snowdon and French 1968; Nettleton et al. 1980). Reactions between swine fever antigen

and sera from cattle that had experienced an infection with the MD virus has been observed

(Darbyshire 1960). Darbyshire (1962) also observed that the precipitating antigen extracted

from the tissues of pigs which had died from CSF was indistinguishable from an antigen

extracted from tissues of cattle affected with MD.

In this survey, the majority of households (99.2%) kept their pigs in pens. These pens

were usually located in the backyard of the house and are made from locally available

materials such as wood, bamboo and palm leaves. Some farmers built more permanent pens

from blocks and concrete and consequently invested more funds in their pig-rearing

enterprise. Keeping pigs outside can allow potential contact with wildlife and the

consequent associated risks of introduction of infections. This has been shown as the mode

of transmission of CSFV from wild boar in Europe (Artois et al. 2002). This mode of

transmission has been reported for other diseases such as pseudorabies, Brucella

spp.,Mycoplasma hyopneumoniae, and porcine reproductive and respiratory syndrome virus

(Vengust et al. 2006). Housing conditions can influence the humoral responses of animals

(Barnett et al. 1987; Griffin 1989; Kelley 1980) which can result in susceptibility to

infections(Bolhuis et al. 2006).

In swine production, biosecurity is defined as the protection of a herd from the

introduction and spread of infectious agents (viral, bacterial, fungal or parasitic) (Amass

and Clark 1999). Therefore, it is important for farmers to understand how potential disease

agents spread and how to protect their farms from the introduction of infection by good

management practices. However, these factors are often neglected in small farms as was

68

apparent in this study where most farmers provided little attention or input to biosecurity.

No farmers adopted practices routinely used in commercial units such as disinfecting pens,

restricting the entry of visitors or providing protective clothing to visitors. Although these

practices play a significant role in intensive commercial piggeries in keeping disease agents

out (Pinto and Urcelay 2003), their benefit in subsistence holder farms may be questioned.

However CSF, along with many other diseases, can be transmitted by contaminated

clothing and footwear (Weesendorp et al. 2008; Dahle and Liess 1992)and a simple

footbath for visitors may help minimise the introduction of CSF into herds.

Provision of an adequate quantity and quality of feed to pigs, including sufficient

amounts and balances of protein and amino acids, energy, essential fatty acids, water,

vitamins and minerals, is essential in maximizing the health and productivity of pigs.

Nutritional deficiencies can result in clinical problems such as abortions, anaemia, bone

fractures, deformed bones, lameness, diarrhoea, poor growth, poor appetite, poor litter size,

reproductive failure and sudden death (The Pig Site Pig Health 2010). Smallholders in West

Timor do not give serious attention to the quality of feed but usually feed readily available

feed stuffs. Agricultural products such as cassava root and leaves, banana steam and leaves,

corn, tofu waste, and coconut pulp are widely used as pig feed in this area. It is important

that the dietary composition of these local ingredients is evaluated to allow composition of

rations that best meet the demands of the local pigs.

Some farmers interviewed highlighted a problem of providing sufficient drinking

water to their pigs, especially in the dry season when some wells dried up. At this time

water was often sourced from local rivers or streams and there was the potential for

contamination by organic and inorganic materials. For example, during the survey in the

district of Belu one local stream used as a water source for pigs was also the site of a local

mining industry, resulting in significant contamination of the stream with manganese which

69

can cause neurotoxicity (Zhang et al. 2003; Erikson et al. 2007), brain damage (Takeda

2003), and fetotoxicity and morphological defects to animals (Sanchez et al. 1993).

3.4.2 Reproduction management and performance

Natural mating is still the normal mating method adopted in most pig herds in West

Timor. However, there is a move towards AI which is currently practiced by 27.4% of the

households. Artificial insemination offers the advantage of being able to introduce better

genetics but requires accurate detection of oestrus by farmers, availability of trained

inseminators with sufficient skill and knowledge to perform the procedures and is more

costly per mating. Boars were commonly exchanged between farms and these generally

originated from within the household’s village. This practice has the potential to spread

infectious agents between groups of pigs. However provided the health status of the

incoming boar is not lower than that of the sows mated, the practice offers the advantage of

farmers not requiring their own adult boars, and the potential to improve the quality of off-

spring if a good class of boar is used. The potential for transmission of CSF was

highlighted by de Smit et al. (1999a), Floegel et al. (2000), and Hennecken et al. (2000) as

adult boars infected with CSFV were shown to excrete the virus in their semen and

therefore could, subsequently, transmit the virus to sows and their offspring.Infected boars

can shed the virus in semen for up to 53 days post-infection allowing the potential

dissemination of the virus throughout a village (Choi and Chae 2003).

With respect to the litter size this was relatively good for a subsistence farming

system with an average litter size of 8.6 piglets born alive (range 5 to 12 piglets/litter).

However the pre-weaning mortality was high (4.1 per litter) resulting in almost 50% of

piglets dying prior to weaning. The percentage of preweaning mortality of piglets in West

Timor was higher than that reported by Craig et al. (2010) in three districts in NTT (Kota

70

Kupang, Kabupaten Kupang, and Manggarai) where preweaning mortality of all herds was

11.4%. This percentage was also higher compared to pigs reared under traditional systems

in India (29.7%) (Kumaresan et al. 2007). The reproductive performance of sows can be

influenced by many factors including environment, disease, feed quality, genetics and

management (Kunavongkrit and Heard 2000). Generally the body condition scores of pigs

in the surveyed households was good, however, a few pigs were in poor condition (Figure

3.4). The poor condition of such pigs is most likely to have arisen from disease, and in

particular those affecting the gastrointestinal system.

Figure 3.4 Pig in poor body condition

The presence of parasites (e.g., Ascaris suum) in the intestine can result in reduced

performance in fattening pigs (Hale et al. 1985; Stephenson et al. 1980), and several

authors (Forsum et al. 1981; Hale, et al.1985; Stephenson et al. 1980) have reported the

correlation between the number of adult worms present in the intestine and reduced weight

gain. The presence of internal nematodes most commonly causes loss of appetite, reduction

in the rate of daily gain, poor feed utilization, and the potential for infection by other

71

pathogens. The losses caused by parasites vary depending upon the geographical region,

type of housing, management, nutrition, pig breed and strain, and species of infecting

parasites (Corwin and Stewart 1999).

With respect to the body condition, variations in the body composition may have

important consequences for production and health at an individual or herd level (Charette et

al. 1996). In modern pig herds, evaluating the body condition of a sow, in particular, is of

considerable importance to achieve optimal production targets (Maes et al. 2004), and in

pigs the ‘thin sow syndrome’, the ‘fat sow syndrome’ and the ‘second parity syndrome’

have been related to problems with the regulation and dynamics of body condition, and

therefore there is a need to adequately monitor body condition (Charette et al. 1996).

However most research on body condition has been restricted to intensively reared pigs and

there is a need for research to determine optimal body condition for pigs raised under

small-holder farmer systems.

3.4.3 Movement of Pigs

This study demonstrated that live pigs are transferred extensively in West Timor

between individuals both by trade or sale, and through social and family ceremonial

exchanges. Traditional trading is still practiced by many farmers where pigs are sold to

relatives or to other farmers. Most pigs were sold in the months of June and July in

preparation to pay for school fees and allowances for their children for the commencement

of the academic year in Indonesia. The spreading of CSFV is facilitated by the movement

of virus excreting pigs within a dense population (Dahle and Liess 1992). The entry of

weaners from different breeding farms to fattening units or to markets carries a high risk of

introducing the virus to susceptible pigs (Beals et al. 1970). The distribution of animals and

markets allows the mixing of a large number of animals from different origins which has

72

the potential to allow the virus to spread from one locality to another (Moennig et al. 2003).

These authors suggested that new animals introduced should be purchased from a limited

number of suppliers, and a vertical production system developed to overcome this problem.

The same authors also outlined that trading of pigs over long distances could facilitate virus

spread, and establishment of a local marketing system could help overcome this problem.

Bigras-Poulin et al. (2007) described the transmission of CSFV in the swine industry in

Denmark. Their study revealed that the movement of pigs would facilitate the spread of the

disease. Ribbens et al. (2009) showed that some herds (sellers of replacement stock) could

potentially spread infection to many recipients, and these authors believed that if disease

remained undetected in these herds, infection could rapidly disseminate to many other

farms through livestock movements.

3.4.4 Pig health, and treatment and prevention of CSF.

Although CSF has been present in West Timor since 1998 and is now considered to

be endemic, very few farmers were aware of the disease and how it was spread. This would

account for the low adoption of vaccination by the farmers, even when it was provided free-

of-charge by the Provincial Government. It is apparent that an educational campaign is

needed about the disease, how it is spread, what the consequence of the disease is and how

it can be controlled. Such a campaign must be specifically developed and directed towards

the farmers. It is important to provide educational material on how diseases are introduced

to a farm and the significance of each of the biosecurity measures in terms of risk reduction

(Casal et al. 2007). Most importantly, education can contribute to people correctly

identifying, treating and preventing the disease. Educational attainment and knowledge has

played an important role in the perception and practice of people in controlling many

diseases including malaria in Nigeria (Dike et al. 2006), bovine trypanosomiasis in Kenya

73

(Machila et al. 2007), and pest management in the Mekong Delta, Vietnam (Heong et al.

1998). Nöremark et al. (2009) and Machila et al. (2007) believed that it was not necessary

for farmers to have advanced education but it was important to have access to suitable

information (extension materials). This should include information on the risks of

outbreaks of contagious diseases, actions required to reduce animal contacts and improve

biosecurity, and awareness of the need to have early notification of disease.

Some farmers who believed their pigs had been vaccinated against CSF, had in fact

administered vitamin B-complex medications to their pigs. It is evident that specific

educational material is required on vaccination. Material developed on Alor Island for the

control of CSF (ACIAR website) could be used to improve farmer awareness of the

disease.

Although newspapers, radio, and television can be used to disseminate information,

in this situation it is believed that farmer meetings would be the best way to improve

awareness of diseases such as CSF and methods of improving animal husbandry,

management and production. Farmer groups have been established in Alor and have

resulted in a significant reduction in the deaths from CSF as well as increased adoption of

new management and improved husbandry practices (ACIAR website).

Further information is required by farmers on methods of disposing of carcasses in

West Timor, especially when a pig dies suddenly. Although only 3.3% of farmers in this

study stated that they would throw a dead body away, this has the potential to spread

disease if it is eaten by a wild animal or if it contaminates drinking water. A few

households reported that they would eat a dead pig and again improved education is

required to minimise the probability of infection of humans with diseases such as anthrax,

which is present in West Timor (Livestock Service 2006).

74

3.5 Conclusions

In this chapter information was provided on the husbandry and management practices

adopted by pig households in West Timor. Most pigs are reared in non-intensive traditional

systems and the rearing of pigs was a secondary occupation to other work. However, pigs

are an essential component of the economy and play important social and cultural roles.

Despite this, the low inputs to pig health make disease control a challenge and there are

significant opportunities to improve productivity through the adoption of good management

practices.

As CSF has been present in Timor since 1998, and it is suspected of resulting in

deaths and losses, a serological survey was conducted to determine the seroprevalence at

the district, sub-district, and village level. The results of this study are outlined in the next

chapter (Chapter Four).

75

CHAPTER FOUR

SEROLOGICAL SURVEY FOR CLASSICAL SWINE FEVER IN

WEST TIMOR

4.1 Introduction

Evidence of infection with CSF was first detected in pigs from the island of Timor

in 1997 (Santhia et al. 1997; Santhia et al. 1998; Satya and Santhia 2009). This disease has

resulted in considerable economic losses for pig farmers, however a thorough study on the

prevalence of this disease on Timor has not been conducted. To address this deficiency a

serological survey for CSF in West Timor, NTT was undertaken. In this chapter the overall

seroprevalence of CSF and differences between districts, subdistricts, and villages are

presented. Such estimates of prevalence can be used by decision makers, such as policy

makers and risk assessors, to make choices relating to which diseases or infections should

be controlled and which ones most resources should be directed to (Cross et al. 2010;

Nielsen and Toft 2009).

The principle objective of prevalence studies is to estimate the frequency of a trait

(disease, infection, protective immunity or exposure to a risk factor) in a population

(Greiner and Gardner 2000). Serological epidemiology is the investigation of infections in

populations through the measurement of specific immunoglobulins or agents in serum to

indicate either historical or current exposure to infectious agents in both individual animals

and populations (Thrusfield 2005). Serological surveys have been used throughout the

world for the diagnosis and surveillance of a range of infectious diseases, including CSF

76

(Moennig and Greiser-Wilke 2008). Antibodies to CSFV in pigs can be detected 2 to 3

weeks after infection (Greiser-Wilke et al. 2007). Serological surveys are also useful for

confirming the diagnosis of CSF in cases with non-specific or atypical clinical signs (Elbers

et al. 2002; Greiser-Wilke et al. 2007; Moennig 1992; Moennig et al. 2003). The virus

neutralisation test (VNT) and ELISAs are the most commonly used tests for detecting

antibody to CSF (Greiser-Wilke et al. 2007; Moennig 2000). The VNT is the most sensitive

and specific method for CSF antibody detection (Moennig 2000), and is regarded as the

gold standard (Greiser-Wilke et al. 2007), however it is less practical for several reasons.

Specifically it is time consuming, taking at least 2 to 3 days or even longer if comparative

testing is required (Moennig 2000) as it is reliant upon cell culture technology (Anonymous

2002; OIE 2004).

The VNT is not suitable for mass screening because it cannot be automated, and it is

not able to discriminate between antibody titres due to field infection with CSFV and

antibodies resulting from immunisation with modified live CSFV vaccines (Greiser-Wilke

et al. 2007). In contrast the ELISAs require less-specialised facilities and can be performed

more rapidly than the VNT (Moennig and Greiser-Wilke 2008). They are therefore

extremely promising tools for screening large numbers of live pigs and are suitable for

routine serological investigations (Depner et al. 1995a; Moennig 2000; Moennig and

Greiser-Wilke 2008). However, the usefulness of the ELISAs is limited because of

potentially low sensitivity (Greiser-Wilke et al. 2007; Moennig and Greiser-Wilke 2008;

van Oirschot 2003), although the ELISAs recently developed have been reported to have

sensitivities in the order of 98% (Sung et al. 2010). The work described in this chapter

represents the first serological survey for CSF conducted in West Timor that has been based

on epidemiologically sound sampling techniques.

77

4.2 Materials and Methods

4.2.1 Sampling and Sample collection

A total of 720 serum samples were collected from pigs older than 3 months of age

from 8 different villages in West Timor between April and May, 2010. The samples were

collected from vaccinated and non-vaccinated pigs, and from both healthy and sick pigs.

The selection of districts, subdistricts, villages, households and pigs for sampling was as

described in Chapter 2. A maximum of 4 pigs, over the age of 3 months, were sampled

from selected farmers from each village (Table 4.1). A minimum of 30 farmers were

selected from each village.

Blood samples were collected as outlined in Chapter Two and data recorded in the

field on a sheet as outlined in Appendix 2.

Table 4.1 Number of farmers interviewed and pigs sampled per village

Districts Subdistricts Villages Number of

farmers

Number of

samples tested*

Kota Kupang

Maulafa Oebobo

Sikumana Oepura Oebobo Oebufu

38

33

37

45

89

89

88

88

Belu

Tasifeto Barat Atambua Selatan

Naitimu Naekasa Fatukbot Lidak

36

42

47

41

90

87

89

89

* Although 90 pigs were sampled in each village, some samples were lost in transit to the laboratory

78

The number of pigs to sample was determined based on an expected prevalence of

25%. This value was chosen after discussions with Dr Maria Geong, Dinas Peternakan

NTT. Dr Geong’s expert opinion was that the seroprevalence in the selected districts of

West Timor was between 20 and 30%. The level of precision was set at 10%, the level of

confidence at 95% and a village pig population of 2000 (based on expert opinion) for

calculation of the sample size using EpiTools (Sergeant 2009). As the diagnostic assay did

not have perfect sensitivity and specificity (Thrusfield 2005) the sample size was calculated

assuming an imperfect test with a sensitivity and specificity of 99% as described by Colijn

et al. (1997). This resulted in a sample size of 82 pigs per village and to allow for potential

losses of sera 90 pigs were sampled per village.

4.2.2 Diagnostic Assay

Sera were tested with a commercial ELISA kit (PrioCHECK®), which is a newly

developed, modified PrioCHECK ELISA for CSFV-Ab. The PrioCHECK® CSFV Ab is a

rapid test to detect antibodies against high, moderate and low virulent strains of CSFV. It

combines a convenient and simple test procedure with high sensitivity and specificity. The

key reagents involve monoclonal antibodies (mAb) that are directed against different

epitopes on the envelope protein E2. The processes of the test are displayed in Figures 4.1

and 4.2.

79

Figure 4.1 ELISA test procedure Source:Prionics 2010

The anti-CSFV mAb is bound to the test plate and the detection antibody is

conjugated to an enzyme that generates a colour reaction. The colour intensity is measured

after incubation and when no colour is produced the sample is considered positive for

antibodies to CSFV (Prionics 2010).

There were four steps followed to perform the PrioCHECK ELISA for the testing of

sera for antibodies to CSF (Figure 4.2). These four steps were preparation; incubation of

sera, conjugates, and antigen; incubation with chromogen substrate; and reading the test. In

the preparation step (Figure 4.2 a), conjugate dilution, antigen, and washing solution were

prepared 15 to 20 minutes before the test was performed. Conjugate dilution involved

diluting the conjugate with the dilution buffer (ready to use); and preparing the lyophilized

antigen and the washing solution (diluted 1 in 200). The next step was the incubation of test

samples, conjugate, and antigen (Figure 4.2 b). Test samples, conjugate, and antigen were

dispensed into the plate wells and incubated at room temperature (22-23°C) for 90 to 95

minutes. The third step involved incubation of plates with chromogen substrate using a

commercially available ready-to-use chromogen-substrate solution (TMBTM) (Figure 4.2 c).

Plates were washed five times, then 100 µl of TMB-solution added and the plates incubated

for 30 minutes at room temperature. Subsequently, colour development was stopped by the

addition of 100 µl 0.5 M stop solution (H2SO4, ready-to-use) (Figure 4.2 d). The final step

80

involved reading the plate (Figures 4.2 e, f). This step was undertaken within 15 minutes of

stopping the colour development by measuring the optical density (OD) of the wells in an

ELISA reader (Stat Fax2100) at 450 nm.

4.2.2.1 Interpretation and calculation of test results

The corrected OD450 of all samples was expressed as the percent inhibition (PI)

relative to the corrected mean OD450 of the ready-to-use reference serum 4. Inhibitions were

calculated as follows:

The sample was considered seronegative if the PI was less than 30%. If the PI was

between 30 and 50% the result was categorised as inconclusive and it was recommended

that the sample be retested using a virus neutralization test (VNT) for CSFV. A seropositive

result was manifest when the PI of the sample was greater than 50%.

81

a) Preparation of components for the test b) Incubation of serum, conjugate and antigen

c) Incubation with Chromogen substrate

d) Adding stop solution to the test plate

e) Plate is ready to be read f) Reading the test with ELISA reader.

Figure 4.2 The test procedure followed for testing samples in the AB&MB Laboratory at the University of Udayana, Denpasar, Bali.

4.2.2.2 Statistical analyses

Data were entered into an ACCESS 2007 database. Data were then extracted to

Excel 2007 and transferred into a statistical package (SPSS Statistics version 17.0) for

subsequent analyses as outlined in Chapter 2.

The true prevalence was estimated by using the following formula as described

by Pfeiffer (2010):

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4.3 Results

4.3.1 Overall Seroprevalence

Although 720 samples were collected from the two selected districts in West Timor,

11 samples were misplaced (lost) prior to testing and consequently results from only 709

samples were available (Table 4.1). Of these 126 were positive resulting in a test

seroprevalence of 17.8% (95% CI: 15.1-20.8%).

The seroprevalence in the district of Kota Kupang (15.0%; 95% CI: 11.4, 19.2%) was

lower than that in Belu (20.6%; 95% CI: 16.5, 25.2%) (χ2 = 3.79, df = 1, P = 0.05).

The highest seroprevalence was detected in the sub-district of Oebobo (25.6%: 95%

CI 19.3, 32.7%) and the lowest in the sub-district of Maulafa (4.5%: 95% 2.0, 8.7%).

Overall there was a significant difference in the seroprevalence between sub-districts (χ2 =

35.1, df = 3, P < 0.001).

83

Table 4.2 Test seroprevalence of CSF in West Timor

District Sub-district

Village Number tested

Apparent Prevalence (95%CI )

Real Prevalence ( 95%CI)

Kota Kupang

354 15.0 (11.4, 19.2) 14.3 (10.8, 18.3)

Maulafa 178 4.5 (2.0, 8.7) 3.6 (1.4, 7.5)

Sikumana 89 3.4 (0.7, 9.6) 2.4 (0.3, 8.1) Oepura 89 5.6 (1.8, 12.6) 4.7 (1.4, 11.4) Oebobo 176 25.6 (19.3, 32.7) 25.1 (18.9, 32.1) Oebobo 88 17.1 (9.9, 26.6) 16.4 (9.3, 25.8) Oebufu 88 34.1 (24.3, 45.0) 33.8 (24.0, 44.6) Belu 355 20.6 (16.5, 25.2) 20.0 (15.9, 24.5)

Tasifeto Barat

177 24.9 (18.7, 31.9) 24.4 (18.2, 31.4)

Naitimu 90 18.9 (11.4, 28.5) 18.3 (10.9, 27.8) Naekasa 87 31.0 (21.5, 41,9) 30.7 (21.2, 41.5)

Atambua Selatan

178 16.3 (11.2, 22.6) 15.6 (10.6, 21.8)

Fatukbot 89 22.5 (14.3, 32.6) 21.9 (13.8, 31.9) Lidak 89 10.1 (4.7, 18.3) 9.3 (4.2, 17.3)

The highest village level seroprevalence was found in Oebufu (34.1%; 95% CI: 24.3,

45.0%) and the lowest in Sikumana (3.4%; 95% CI: 0.7, 9.6%) (Table 4.2). Overall there

was a significant difference in the seroprevalence between villages (χ2 = 53.2, df = 7, P <

0.001).

The overall real prevalence for West Timor was 17.1% (95% CI: 14.4, 20.1%). As

with apparent (test) prevalence, the highest village real prevalence was detected in Oebufu

33.8% (95% CI: 24.0, 44.6) and the lowest in Sikumana 2.4% (95% CI: 0.3, 8.1). The

84

highest real prevalence was found in the sub-district Oebobo 25.1% (95% CI: 18.9, 32.1)

and the lowest in Maulafa 3.6% (95% CI: 1.4, 7.5).

Table 4.3 Herd level prevalence of CSF in the villages, subdistricts and districts sampled.

District Sub-district Village # Herd

tested # Herds positive

% Positive herds (95% CI)

Mean Prevalence in positive herds (95%

CI) Kota Kupang 153 40 26.1 (19.4, 33.9) 68.9 (61.0, 76.1)

Maulafa 71 8 11.3 (5.0, 21.0) 68.9 (61.0, 76.1)

Sikumana 38 3 7.9 (1.7, 21.4) 58.3 (41.2, 74.0)

Oepura 33 5 15.2 (5.1, 31.9) 65.0 (46.2, 80.9)

Oebobo 82 29 35.4 (25.1, 46.7) 70.7 (59.8, 80.1)

Oebobo 37 11 29.7 (15.9, 47.0) 55 (38.0, 71.1)

Oebufu 45 20 44.4 (29.6, 60.0) 77.4 (62.7, 88.4)

Belu 166 53 31.9 (24.9, 39.6) 64.8 (56.8, 72.2)

Tasifeto Barat 78 32 41.0 (30.0, 52.7) 62.2 (49.6, 73.7)

Naitimu 36 13 36.1 (20.8, 53.8) 57.7 (40.4, 73.7)

Naekasa 42 20 47.6 (32.0, 63.6) 65.4 (46.3, 81.5)

Atambua Selatan 88 22 25.0 (16.4, 35.4) 68.6 (58.0, 78.0)

Fatukbot 47 12 25.5 (13.9, 40.3) 79.8 (65.7, 90.0)

Lidak 41 7 17.1 (7.2, 32.1) 48.9 (33.2, 64.8)

With respect to the herd level seropositivity, of the 319 herds tested 93 herds (29.8%;

95% CI 24.8, 35.2%) had one or more seropositive pigs. The mean seroprevalence in

positive herds was 66.5% (95% CI 24.0, 34.4%) (Table 4.3). The lowest herd prevalence

was in the village of Sikumana (7.9%: 1.7, 21.4%) with a prevalence in positive herds of

85

58.3% (41.2, 74.0%). The highest herd prevalence was in the village of Oebufu (44.4%:

29.6, 60.0) with a mean seroprevalence in positive herds of 77.4% (62.7, 88.4%). There

was a significant difference between villages in the number of herds with one or more

positive pigs (χ2 = 53.2, df = 7, p = 0.001).

At the sub-district level, the lowest herd seroprevalence was found in the sub-district

of Maulafa in the district of Kota Kupang (11.3%: 5.0, 21.0) with a mean seroprevalence in

positive herds of 62.5% (50.1, 73.8). The highest herd seroprevalence was in the subdistrict

of Tasifeto Barat from the district of Belu (41.0%; 95% CI 30.0, 52.7%) with a mean

prevalence in positive herds of 62.2% (95% CI 49.6, 73.7%). There was a significant

difference in the number of positive herds between sub-districts (χ2 = 35.1, df = 3, p =

0.001). The herd level seropositive in Belu (31.9%: 24.9, 39.6) was similar to that in

Kupang (26.1%:19.4, 33.9) (χ2 = 1.29, df = 1, p = 0.256, and OR 1.33; 95% CI 0.81, 2.15).

4.4 Discussion

4.4.1 Prevalence of CSF in West Timor

Serological surveys are used to identify patterns of current and past infections

(Thrusfield 2005). In this study, a serological survey was carried out to identify the

seroprevalence in a sample of pigs from two districts, four sub-districts and 8 villages in

West Timor. Samples were collected from pigs which were at least 3 months of age and

included both vaccinated and unvaccinated pigs and healthy and sick pigs. Samples were

not collected from pigs younger than 3 months of age as samples from this age group may

still contain maternally derived antibodies. These maternal antibodies, ingested through the

colostrum, can provide protection to infection for approximately two months (Kaden and

Lange 2004;Terpstra 1977).

86

In this study some seropositive pigs were detected in all of the sampled villages

with the highest seroprevalence in Oebufu (pig prevalence - 34.1%) and the lowest in

Sikumana (3.4%). The seropositive reactions are likely to indicate that these pigs have been

exposed to CSFV (Thrusfield 2005). Condy et al.(1969) reported that the significance of

specific antibody titres in animals is dependent upon a number of factors including: the

period of time after infection; the rate of decline of existing convalescent titres; the species

and age of the animals; and whether the virus used in the test is heterologous or

homologous.In this study however, it could also be due to pigs having been vaccinated

against CSF (Kaden et al. 2000). In Vietnam, the relationship between vaccination and

antibodies in 70 serum samples was examined. In that study it was found that 79% of

vaccinated breeders had antibodies to CSF which was higher than that expected through the

irregular adoption of vaccination (Kamakawa et al. 2006). During the CSF epidemic in

wild boar in the Eifel region of the German federal state of Rhineland-Palatinate during the

period from 1999 to 2005, the seroprevalence in pigs increased constantly after the first

four immunisation campaigns and reached a stable level (77 – 87%) in the following 2

years (von Ruden et al. 2008). In the current study, only 34 (4.8%) of the sampled pigs had

been vaccinated for CSFV, although 29.4% were seropositive to CSFV. The vaccine used

in West Timor is the live attenuated Chinese strain (C-strain) vaccine. The C strain vaccine

is generally accepted to be very safe in pigs of all age groups, providing complete

protection, i.e. sterile immunity in vaccinated pigs (Kaden and Lange 2001; Suradhat

2007), and induces detectable neutralizing antibodies in vaccinated pigs 2 to 3 weeks

following primary vaccination (Precausta 1983; Terpstra et al.1990). However in some

reported cases no neutralizing antibodies were detected at the time of challenge, even

though vaccine induced protection had been achieved (Launais et al. 1978; Rumenapfet al.

1991). Such findings suggest a role for cell-mediated immunity (CMI) during the early

87

phases of immunity (Suradhat 2007). The use of C-strain vaccine however has a potentially

negative impact with respect to laboratory testing. The ELISA test is not as sensitive as

virus isolation (Van Oirschot 2003), is not specific for CSFV (Depner et al. 1995a;Shannon

et al. 1993), and cannot differentiate between naturally induced antibodies to those induced

by vaccine (Greiser-Wilke et al. 2007; Moennig 1992; Moennig et al. 2003). There is

therefore a need for a vaccine that induces an immunity that can be differentiated from that

induced following natural infection ie a “diva vaccine” (Greiner and Gardner 2000).

Factors that influence the seroprevalence have been reported in both feral and

domestic pigs. In feral pigs, a high seroprevalence, and persistent or endemic CSF are

considered to be associated with a high population density (Ruiz-Fons et al. 2008; Vicente

et al. 2005), seasonal breeding (Kern et al. 1999), management (hunting and vaccination)

(Rossi et al. 2010; Zanardi et al. 2003), regular contact between domestic and wild pigs

(Artois et al. 2002), and contiguous populations (Cowled and Garner 2008). In addition,

CSF could persist in dense wild boar populations where there are no barrier restrictions due

to an increased availability of young animals (Ruiz-Fons et al.2008). While in domestic

pigs, some factors have also been reported to influence the incidence of CSFV including

the density of piggeries resulting in spread to neighbouring farms (Mintiens et al. 2003);

larger herd size and frequent pig movements (Crauwels et al. 2003; Elberset al. 1999); and

swill feeding (Fritzemeier et al. 2000) as well as poor management (Ribbens et al., 2008).

The overall prevalence in this study (17.8%, 95% CI: 15.0, 20.8%) was lower than

the expected prevalence (between 25% and 30%). Santhia et al. (2001) reported the

seroprevalence of CSF in Kabupaten (District) Kupang of 10.8% which was lower than that

obtained in the current study. A change in prevalence can be influenced by either a change

in the duration of the disease or its incidence (Thrusfield 2005). The duration of CSFV can

be either short or long depending upon the course of disease (acute or chronic). The acute

88

form lasts less than 4 weeks and the infected pigs may either recover completely or die

(Artois et al. 2002), whereas the chronic form lasts longer where animals usually survive

for two to four months before they die (Moennig and Greiser-Wilke 2008). Additionally, if

a pig is exposed to a low virulent strain of CSFV, the pig may recover rapidly and therefore

the duration of disease is short, although the production of antibodies by these pigs may

result in an increased seroprevalence. Short periods of virus excretion and subsequent

antibody response have been observed in postnatal infections with low virulent strains

(Dahle and Liess 1992). Furthermore, antibodies against CSFV become detectable 2–3

weeks after exposure to the virus (Laevens et al. 1998). Therefore if a sample is taken

during the early phase of the disease no antibody may be detected. Conversely if a virulent

strain is present, pigs may die prior to developing an immune response.

In this study, it was found that the seroprevalence varied between villages and sub-

districts. The highest herd level prevalence was found in the village of Oebufu and the

lowest in Sikumana, both of which are in the district of Kota Kupang. In contrast the

highest herd prevalence was in the sub-district of Tasifeto Barat in the district of Belu, and

the lowest in Maulafa in the district of Kota Kupang. Overall the herd level prevalence was

higher in Belu district than in Kota Kupang, even though the general management,

husbandry and type of pigs was similar between the two districts. In the following chapter

potential risk factors which may account for such differences are examined in greater detail.

Gardner and Blanchard (1999) described two sources of variability in the results of

a serological test: biological variation in the response of infected and non-infected pigs; and

variation attributable to the test (including variation in the way that laboratories or

technicians perform or interpret the test and laboratory errors). In relation to biological

variation, these authors further described that for infected pigs, the serological response

depends upon the duration of infection, the challenge dose, whether the infection is

89

subclinical or clinical, whether the disease is systemic or mild and localized, the presence

of other concurrent infections, and host factors. Additionally, for non-infected pigs,

exposure to cross-reacting organisms, vaccination against the agent, or vaccination against

other agents through nonspecific immune stimulation might cause elevated responses in

some pigs and lead to false-positive results. The serological results can differ between

populations, as a result of differences in the severity or stage of disease at the population

level (Pfeiffer 2010). It was possible in the current study that the tested pigs were in the

convalescent stage of the disease. In Sardinia, serological studies have shown significant

year-to-year variation in the seroprevalence in two infected areas, with peaks up to 50%.

This suggests that waves of infection are followed by a period when the virus tends to fade

out (Laddomada 2000). In the Netherlands, seropositive pigs have been associated with a

high BVDV-seroprevalence in cattle (Kramps et al. 1999; Mars and Van Maanen 2005),

and the prevalence of CSFV decreases in line with a decrease in the number of farmers

raising multiple species of production animals on the same premises (Loeffen et al. 2009).

Another factor that contributes to the high prevalence of CSFV in the domestic pig

population is the high incidence of CSF in wild (feral) pigs (Sus scrofa sp.). Infection has

been reported in the wild boar population in some areas of France, Germany, and Italy

(Laddomada 2000). Wild boars are considered as susceptible to CSFV as are domestic pigs,

and transplacental transmission of virus in the wild sows has been experimentally

reproduced, resulting in the birth of carrier piglets (Brugh et al.1964; Depner et al. 1995b).

With respect to the situation in Timor, the transmission of CSFV from feral to domestic

pigs is possible because wild pigs are present in this region. Some studies have shown that

the presence of wild boar in a domestic pig area poses a great risk for the spread of CSFV

to domestic pigs (Laddomada 2000). Studies carried out in Germany, for example, have

shown that 46% of the primary outbreaks of CSF occurring in domestic pigs from 1993 to

90

1997 were caused by direct or indirect contact with infected wild boar (Fritzemeier et al.

1997). A model simulating the spread of CSFV from wild-boar populations to domestic pig

herds in Denmark predicted that CSFV would be transmitted from the domestic pig

population to wild boar if the infected domestic pig herd was located close (<5 km) to an

area with wild boar. If an epidemic then occurred in a sow herd, the infection could

subsequently be spread through the movement of pigs (Boklund et al. 2008). In addition,

most outbreaks in domestic pigs in Germany occurred in geographical regions where the

wild boar population was affected by CSF (Fritzemeier et al. 2000). As wild and domestic

pigs share pathogens (Lipowski 2003), wild pigs therefore play a significant role as CSFV

reservoirs for the domestic pig population (Ruiz-Fons et al. 2008; Meng et al. 2009).

4.5 Conclusions

In West Timor infection with CSF has previously led to a large number of pig deaths

resulting in significant loss of income for farmers as well as high costs for the Government

through the associated expenses of implementing control programs. This study has

estimated the seroprevalence at the district, sub-district and village level in West Timor.

This study highlights the need for establishing proper control programs for CSF in West

Timor to potentially facilitate the control and eradication of the disease.

Before a control program can be implemented it is important to identify risk factors

that are associated with disease. In the following chapter the results from a questionnaire

administered at the time of sera collection are presented to highlight putative risk factors

which may be linked with the presence of antibodies to CSF.

91

CHAPTER FIVE

QUESTIONNAIRE AND RISK FACTOR ANALYSIS FOR CLASSICAL SWINE

FEVER IN WEST TIMOR

5.1 Introduction

The existence of CSF in an area and the potential for introducing the disease into a

new area can be associated with the presence of certain risk factors. Identification of these

risk factors is important in understanding the transmission of disease and for the

development of effective prevention, control and eradication programs. Farmers are a

valuable source of information about potential risk factors and associated management and

husbandry practices linked with disease as they have many years of experience in raising or

trading livestock. In many South-East Asian nations farmers own only a small number of

livestock and hence are generally very knowledgeable about the health and well-being of

their animals. In the study described in this chapter, questionnaires were administered to

farmers from two districts in West Timor. Questionnaires are one of the most commonly

used tools for the collection of data in veterinary epidemiological research and can be used

in a wide variety of clinical and epidemiological research settings to understand the

epidemiology of many infectious diseases (Dohoo et al. 2003; Dufour 1999).

The objective of the study described in this chapter was to identify potential risk

factors associated with CSF infection in West Timor. In particular factors involved in the

management and husbandry of pigs were investigated.

92

5.2 Materials and Methods

The area of study, the development, implementation and administration of the

questionnaire, and the data collection methods adopted in this study have already been

outlined in Chapter 2.

5.2.1 Data analysis

Data were entered into a Microsoft ACCESS 2007 database and exported into a

statistical package (SPSS Statistics version 17.0) for subsequent analysis (Chapter 2). For

univariable analyses, potential risk factors were compared with the ELISA test result

against CSF (seropositive versus seronegative) using the Pearson’s chi-square test for

independence. A Fisher’s exact test was used to report statistical significance of association

when one of the cells in a 2x2 table had an outcome or expected count less than 5. For

continuous variables the mean value for seropositive pigs was compared with the mean

value for seronegative pigs with an ANOVA, after testing for normality of data and

homogeneity of variance. A p-value less than 0.05 was taken as evidence of a significant

difference. Odds ratios (OR) and their 95% confidence intervals (95% CI) were also

calculated to measure the degree of association between putative risk factors and the

presence of CSF (Kahn and Sempos 1989).

Factors with a significance level of P < 0.25 and which were considered to be

biologically important were offered to the multivariable binary logistic regression model. A

binary logistic regression model was built using a manual backwards elimination process as

described by Dohoo et al. (2003), with a significance level of P > 0.05 as the criterion for

removal of a variable from the model. Variables with high collinearity (r > 0.8) were

excluded from the analysis. The analysis commenced with a full or saturated model and

variables were eliminated from the model in an iterative process. The level of significance

for a factor to remain in the final model was set at 5%. Because of the likely presence of

93

additional variation due to the clustering of herds in villages, village was incorporated as a

random effect in the model. Two-way interaction terms among the explanatory variables

were examined after identification of the reduced set main effects. Each interaction was

added to the model and the significance assessed in the same way as for the explanatory

variables. The suitability of the final model was assessed based on the Hosmer and

Lemeshow and Nagelkerke R Square values (Hosmer and Lemeshow, 2000).

5.3 Results

5.3.1 Univariable analyses of putative risk factors for CSF in West Timor

Putative risk factors that were potentially involved in the spread of CSF infection in

West Timor were investigated. In the univariable analyses, seven categories of potential

risk factors for the spread of CSFV (pig household characteristics, farm structure and herd

information, husbandry, reproductive management, pig movement, health status of pigs,

knowledge of pig owners on CSFV and vaccination, and body condition of pigs) were

investigated. In Tables 5.1, 5.2, and 5.3 the associations between the categorical putative

risk factors and serological result for CSF are summarised.

94

Table 5.1 Risk factors for CSF in West Timor (categorical variables)

Variables % pigs seropositive

OR (95% CI) P

Level of Education: – Completed Primary School, Junior

High School or had no formal education

– Completed Senior High School or

University

14.7

19.6

1.42 (0.99, 1.60)

1.00

a0.176*

Training attendance: –

ever attended animal training

– ttended animal training

16.3

25.0

0.58 (0.06, 5.67)

1.00

0.511*

Main occupation: –

ivil servant/army/police

– etired

–

ther occupation

– gricultural farmer

18.4

14.0

21.4

5.0

4.3 (0.56, 32.77)

3.1 (0.40, 24.04)

5.2 (0.48, 56.10)

1.0

0.271

Pig rearing system: - Traditional

- Semi-intensive

16.7

16.7

1.00 (0.12, 8.66)

1.00

1.000*

Cattle ownership: - Own cattle

- Did not own cattle

82.9

16.4

24.64 (9.91, 61.23)

1.00

0.530*

Goat ownership: - Own goats

- Did not own goats

35.3

15.8

2.90 (1.04, 8.06)

1.00

a0.045*

95

Variables % pigs seropositive

OR (95% CI) P

Purpose for keeping pigs: - For emergency needs

- For traditional and religious

ceremonies

- For own consumption in the family

- For payment of school fees

20.1

14.3

7.1

4.7

5.13 (1.57, 16.75)

3.39 (0.30, 37.87)

1.56 (0.33, 7.31)

1.00

a0.001

Pig raising type: - Fattening

- Fattening and breeding

- Breeding

13.7

18.0

16.0

0.84 (0.43, 1.62)

1.16 (0.67, 1.98)

1.00

0.551

How were pigs kept? - Pigs were tied up

- Pigs were free to roam

- Pigs were kept in pens

66.7

25.0

16.5

10.2 (0.91, 113.3)

1.69 (0.17, 16.5)

1.00

a0.064

Construction of pen’s roof: - Pig pen’s roof made from palm leaves

- Pig pen’s roof made from tin

18.0

15.9

1.16 (0.67, 2.02)

1.00

0.567*

Construction of pen’s wall: - Full-height brick

- Wood/bamboo

- Hal height of brick

20.0

16.8

16.3

1.28 (0.18, 1.66)

1.04 (0.77, 1.29)

1.00

0.728

Material of pen floor: - Dirt - Slatted wooden/bamboo floor - Solid wood/bamboo - Concrete

25.0

16.7

15.8

15.7

1.78 (0.77, 4.13)

1.07 (0.23, 4.99)

1.00 (0.40, 2.49)

1.00

0.597

Pig pen cleaning: - Did not clean the pig’s pen

- Cleaned the pig’s pen

18.6

15.8

1.22 (0.70, 2.14)

1.00

0.461*

Frequency of cleaning pens: - Less frequently than once a day - At least daily

8.3

16.0

0.48 (0.06, 9.28)

1.00

0.701*

96

Variables % pigs seropositive

OR (95% CI) P

Washing pig: - Did not wash pigs

- Washed pigs

16.7

16.2

1.04 (0.65, 1.66)

1.00

a0.905*

Frequency of washing pigs: - Less frequently than once a day - At least daily

33.3

16.1

2.61 (0.23, 29.3)

1.00

0.413*

During the day when are pigs looked after (inspected)?

- In the afternoon only - In the morning only - In both the morning and afternoon

50.0

18.2

16.4

5.10 (1.01, 25.7)

1.13 (0.24, 5.34)

1.00

a0.175

Time spent looking after pigs each day? - 30 minutes - 60 minutes

17.0

11.3

1.60 (0.66, 3.87)

1.00

0.336*

Water source: - Local stream/ river - Tap/reticulated source - Well

17.4

16.4

16.0

1.11 (0.22, 2.99)

1.03 (0.34, 3.08)

1.00

0.990

How often do you feed your pigs? - Pigs fed once daily

- Pigs fed twice daily

- Pigs fed three times daily

33.3

17.3

9.1

5.00 (0.37, 68.08)

2.10 (0.73, 6.03)

1.00

a0.215

Swill feeding: - Swill fed to pigs

- Did not feed swill to pigs

17.5

2.5

8.3 (1.12, 61.20)

1.00

a0.012*

Do you cook the swill before you feed your pigs?

- Swill not cooked before fed to pigs

- Swill cooked before fed to pigs

18.2

17.0

1.09 (0.67, 1.79)

1.00

0.705*

How long do you cook the swill? - Swill cooked for an uncertain time

- Swill cooked for as long as 90

minutes

17.5

11.1

1.69 (0.21, 13.83)

1.00

0.607*

97

Variables % pigs seropositive

OR (95% CI) P

Mating method: - Practice natural mating

- Practice artificial insemination

20.6

14.3

1.56 (0.75, 3.21)

1.00

0.303*

How do you practice natural mating? - Use own boar

- Use borrowed boar from the same

village

- Use borrowed boar from outside the village

18.2

24.5

25.0

0.67 (0.07, 6.78)

0.97 (0.10, 9.80)

1.00

0.418

New pig introductions: - No pigs introduced in the last 12

months

- Pigs introduced in the last 12 months

4.6

18.0

1.00

4.55 (1.41, 14.29)

a0.004*

How did you get the pigs? - Pigs given as a gift by family/relative

- Purchased the pigs

66.7

4.48

0.22 (0.07, 0.71)

1.00

a0.045*

Origin of new pigs: - Same village - Different village in the same sub-district - Another sub-district in the same district - Another district

11.8

10.0

8.3

5.6

2.27 (0.23, 24.7)

1.89 (0.11, 37.18)

1.55 (0.08, 30.02)

1.00

0.342

Why did you buy the pigs? - Pigs bought as a boar for the herd

- Pigs bought to be raised

12.5

6.5

2.07 (0.20, 21.24)

1.00

1.000*

Where did you purchase the pigs from? - Pigs purchased from markets

- Pigs purchased from other farmers

5.0

2.2

2.32 (0.14, 38.99)

1.00

0.524*

98

Variables % pigs seropositive

OR (95% CI) P

Origin of the pigs purchased: - Pigs purchased from within the

village

- Pigs purchased from outside the village

5.5

7.1

0.75 (0.07, 7.81)

1.00 1.000*

Where do you sell pigs? - Pigs sold outside the district

- Pigs sold inside the village

- Pigs sold outside the village in the

same district

20.0

16.7

11.1

2.00 (0.15, 26.24)

1.60 (0.08, 32.80)

1.00

0.591

To whom did you sell your pigs? - Pigs sold to vendors

- Pigs sold to other farmers

- Pigs sold to restaurant owners

- Pigs given to family/relatives

33.3

20.0

20.0

11.1

4.00(0.24, 100.17)

2.00 (0.10, 19.9)

2.00 (0.14, 42.99)

1.00

0.928

Likelihood of selling pigs when money needed:

- Likely to sell pigs when need money

- Very likely to sell pigs when need money

33.3

16.5

2.53 (0.46, 14.05)

1.00 0.513*

Likelihood of selling a sick pig: - Very unlikely to sell a sick pig

- Unlikely to sell a sick pig

- Likely to sell a sick pig

15.2

17.4

16.7

0.89 (0.10, 7.95)

1.05 (0.12, 9.15)

1.00

0.574

Likelihood of selling an old pig: - Very unlikely to sell an old pig

- Unlikely to sell an old pig

- Likely to sell an old pig

- Very likely to sell an old pig

33.3

33.3

16.0

16.5

2.53 (0.21, 30.7)

2.53 (0.41, 15.8)

0.96 (0.27, 3.43)

1.00

0.895

Likelihood of selling pigs in January: - Likely to sell pigs in January

- Unlikely to sell pigs in January

50.0

16.5

5.04 (0.31, 81.41)

1.00

0.536

99

Variables % pigs seropositive

OR (95% CI) P

Likelihood of selling pigs in February: - Likely to sell pigs in February

- Unlikely to sell pigs in February

50.0

16.5

5.04 (0.31, 81.41)

1.00

0.536

Likelihood of selling pigs in March: - Likely to sell pigs in March

- Unlikely to sell pigs in March

50.0

16.5

5.04 (0.31, 81.41)

1.00

0.536

Likelihood of selling pigs in April: - Likely to sell pigs in April

- Unlikely to sell pigs in April

40.0

17.6

3.13 (0.52, 18.9)

1.00

0.583*

Likelihood of selling pigs in May: - Likely to sell pigs in May

- Unlikely to sell pigs in May

50.0

16.64

5.01 (0.31, 80.87)

1.00

0.536

Likelihood of selling pigs in June: - Likely to sell pigs in June

- Unlikely to sell pigs in June

20.0

16.64

1.25 (0.14, 11.34)

1.00

1.000*

Likelihood of selling pigs in July: - Likely to sell pigs in July

- Unlikely to sell pigs in July

18.8

7.3

2.93 (1.42, 6.02)

1.00

a0.002*

Likelihood of selling pigs in August: - Likely to sell pigs in August

- Unlikely to sell pigs in August

18.6

7.1

2.98 (1.39, 6.37)

1.00

a0.002*

Likelihood of selling pigs in September: - Likely to sell pigs in September

- Unlikely to sell pigs in September

20.0

16.4

1.27 (0.14, 11.5)

1.00

0.594*

Likelihood of selling pigs in October: - Likely to sell pigs in October

- Unlikely to sell pigs in October

50.0

16.4

5.09 (0.32, 82.16)

1.00

0.536

Likelihood of selling pigs in November: - Likely to sell pigs in November

- Unlikely to sell pigs in November

10.2

19.3

0.48 (0.27, 0.83)

1.00

a0.009*

Likelihood of selling pigs in December: - Likely to sell pigs in December

- Unlikely to sell pigs in December

11.6

18.7

0.57 (0.34, 0.96)

1.00

a0.037*

100

Variables % pigs seropositive

OR (95% CI) P

Reason for selling pigs in selected months: - Paying for school fees

- Emergency needs

- Pig was large enough to sell

- Many buyers looking for pigs

18.6

19.4

16.7

9.09

2.28 (1.09, 4.74)

2.41 (0.96, 6.01)

2.00 (0.21, 19.05)

1.00

a0.081

Reason for not selling pigs in the selected months:

- Few buyers and no emergency needs

- No emergency needs

- Few buyers

19.0

18.6

8.0

2.69 (0.96, 7.53)

2.61 (1.26, 5.41)

1.00

a0.027

How did you sell pigs? - Pig sold from home

- Pig sold at the market

16.7

10.8

1.65 (0.57, 4.79)

1.00

0.489*

Did you have sick or dead pigs in the 3 month period preceding the survey?

- Had a sick or dead pig in the 3 month period preceding the survey

- Didn’t have a sick or dead pig in the 3

month period preceding the survey

17.9

17.7

1.01 (0.49, 2.06)

1.00

1.000*

Gender of sick pig: - Castrated male

- Female

- Entire male

33.3

16.7

15.6

2.70 (0.39, 18.93)

1.08 (0.18, 6.49)

1.00

0.579

Clinical signs observed in sick pig: - Loss of appetite

- Pyrexia and lethargy

13.2

33.3

0.30 (0.07, 1.39)

1.00

a0.191

What was done with sick pigs? - Nothing

- Treated themselves using own

medicines

- Used natural medicines pigs

- Contacted vet or vet assistant

16.7

25.0

20.5

66.7

0.10 (0.01, 0.59)

0.17 (0.01, 0.91)

0.13 (0.01, 0.43)

1.00

a0.142

101

Variables % pigs seropositive

OR (95% CI) P

What was done with the body/bodies of dead pigs?

- Burnt

- Buried

- Eaten

- Thrown away

25.0

17.2

3.1

31.6

0.72 (0.06, 8.46)

0.45 (0.17, 1.22)

0.07 (0.01, 0.64)

1.00

a0.036

What do you usually do with the body of pigs dying suddenly?

- Usually bury pigs dying suddenly

- Usually eat pigs dying suddenly

16.7

16.7

1.00 (0.12, 8.66)

1.00

1.000*

Do you think the majority of your pig(s) are?

- Fat

- Not skinny or fat

- Skinny

16.7

25.8

13.4

1.29(0.15, 11.51)

2.25 (1.36, 3.73)

1.00

0.363

Have you heard about CSF? - Heard about CSF

- Never heard of CSF

30.0

15.9

0.44 (0.16, 1.18)

1.00

a0.118*

Where did you hear about CSF? - Heard about CSF from friend

- Heard about CSF from TV, radio,

newspaper

42.1

20.0

2.33(0.22, 25.25)

1.00

0.521*

Have your pigs ever been vaccinated against CSF?

- Pigs never vaccinated against CSF - Pigs have been vaccinated against

CSF

15.5

29.4

1.00

2.26 (1.04, 4.92)

a0.052*

Pigs not vaccinated because:

- Do not believe in vaccination

- Use natural medicines instead of vaccines

- Not at home when vaccinator came

33.3

16.1

10.5

4.25 (0.26, 70.8)

1.63 (0.37, 7.19)

1.00

0.485

102

Variables % pigs seropositive

OR (95% CI) P

Reason pigs vaccinated: - The veterinarian came and

vaccinated my pigs

- Wanted healthy pigs

33.3

27.3

1.33 (0.29, 6.12)

1.00

0.714*

How frequently are your pigs vaccinated for CSF?

- Vaccinate pigs once only

- Vaccinate pigs yearly

13.6

58.3

0.11 (0.02, 0.60)

1.00

a0.015

Body Condition Score: - 1

- 2

- 3

- 4

11.1

16.7

18.6

20.0

0.50 (0.04, 5.70)

0.80 (0.22, 2.95)

0.91 (0.25, 3.31)

1.00

0.867

When was your herd last vaccinated for CSF?

- Herd vaccinated more than 6 months ago

- Herd vaccinated within last 6 months

25.0

31.8

0.71(0.15, 3.49)

1.00

a0.169

* Result of Fisher’s Exact Test because one or more cells were less than 5 aP<0.25 and offered to the multivariable logistic regression model The univariable analyses identified 32 risk factors that were linked with the

serological status of pigs in West Timor. These variables with P-values < 0.25 were offered

to the multivariable logistic regression model.

5.3.2 Analysis Of Variance (ANOVA) for Continuous variables

An ANOVA was performed to test for differences between groups of continuous

variables and the results are presented in Tables 5.2. Three factors were associated with

increased probability of being seropositive to CSF. Female pigs between 3 to 6 months of

age were more likely to be seropositive than were male and castrated males of the same age

103

(P = 0.022). Male pigs between the age of 6 to 12 months were more likely to be

seropositive than were female and castrated males (P = 0.023). In pigs over the age of 12

months of age, females were more likely to be seropositive than were entire and castrated

males (P = 0.044).

Table 5.2 Risk factors for CSF in West Timor (continuous variables).

Number of animals owned Positive herds

(mean) Negative

herds (mean) P value

Cattle owned 0.24 0.25 0.943 Goats owned 0.14 0.06 0.128 Pig owned < 3 months:

- Female - Male - Castrated male

3-6 months:

- Female - Male - Castrated male

6-12 months

- Female - Male - Castrated male

> 12 months – Female

– Male

– Castrated male

1.00

4.00

2.33

2.23

2.34

1.61

1.57

1.00

2.00

3.33

1.17

1.00

3.63

4.57

1.33

1.57

2.02

1.75

1.75

1.48

1.31

1.96

1.10

1.33

0.052

0.356

0.079

0.022

0.313

0.504

0.620

0.023

0.190

0.044

0.625

0.545

104

Table 5.2 Risk factors for CSF in West Timor (continuous variables)…..continued

Number of animals owned Positive herds

(mean) Negative

herds (mean) P value

Pig breeds owned

– Local breed

– Crossbreed

– Pure breed

2.67

3.07

38.0

2.82

3.22

15.08

0.677

0.675

0.052

Number of pigs purchased in the last 12 months 1.00 1.32 0.486

First partum: – Litter size

– Total number of normal

piglets born

– Total number of piglets born dead

– Total number of piglets

weaned

6.00

6.00

5.00

1.00

9.00

9.00

4.13

5.35

0.188

0.188

0.672

0.233

5.3.3 Multivariable analysis

The final model was produced using backward conditional binary logistic regression

and the results are displayed in Table 5.3. Three variables (factors) were retained in the

final model. The most strongly associated factor with CSF was introducing a pig or pigs in

the preceding 12 month period (P =0.01; OR=4.7; 95% CI 1.5, 15.7). Farmers who kept

goats or sheep were more likely (P=0.022; OR 3.4; 95% CI 1.2, 9.8) to have infected pigs

than owners who did not keep these species of livestock. Farmers who had vaccinated pigs

105

against CSF were also more likely to have seropositive animals (P=0.035; OR = 2.3; 95%

CI 1.1, 5.1).

The final model had a reasonable fit with a chi square value for the Hosmer and

Lemeshow Test of 3.48 (P = 0.63). The Nagelkerke R square value was 0.344 suggesting

that 34.4% of the variability could be explained by the final set of variables.

Table 5.3 Multivariable analysis of potential risk factors for CSF in West Timor

Variable name ß P OR 95% CI for OR

Lower Upper

Constant Own one or more goats Introduced pigs in the last 12 months Vaccinated pigs against CSF

-3.19

1.23

1.57

0.85

0.000

0.022

0.010

0.035

3.42

4.78

2.33

1.20

1.46

1.10

9.81

15.71

5.12

5.4 Discussion

5.4.1 Characteristics of the interviewed households

Education plays an essential role in the management of a successful farm which

includes the prevention of disease on their farms and the importance of education was

highlighted in Chapter 3.In the current study a higher seroprevalence was found in animals

owned by tertiary educated farmers than by others. This higher seroprevalence was directly

linked to the increased use of vaccine in this cohort of farmers where 9.9% of the pigs had

been vaccinated for CSFV and 29.4% of these were positive to CSFV ELISA test compared

to lower educated farmers where only 4.5% of the pigs had been vaccinated.

Farm characteristics (farm type, farm size, farm income) and farmer capacity

(specialized training and knowledge) have been shown to be significant determinants of a

106

farm’s environment (Yiridoe et al. 2010). However in this study extra training of farmers

(formal animal training) was not significantly associated with the presence of CSFV in

West Timor. This is most likely due to the endemic nature of the disease in West Timor

(Chapter 4) and the general absence of implementation of biosecurity practices (Chapter 3).

5.4.2 Farm structure and herd information

The presence of cattle on the same premises as pigs has previously been identified as

a risk factor for infection with BVDV (Liess and Moennig 1990; Crauwels et al. 2003). In

this study although herds with cattle were more likely (OR=24) to have seropositive pigs

than herds without cattle, this was not significant in the multivariable analysis. The

presence of small ruminants in the neighbourhood of swine herds has previously been

linked to infection of pigs with CSF (Loeffen et al. 2009). In the current study in the

multivariable analysis farmers who kept goats were 2.9 times more likely to have infected

pigs than were those who did not keep this species. In West Timor, goats and pigs are

commonly raised together or kept in the same locality. Goats are known to be a host for

border disease (BD), which is also caused by a pestivirus that is closely related to CSFV

and BVDV (Nettleton et al. 1998). The presence of antibodies to BVDV or BDV in pigs

may provide some protection against the transmission of CSFV in and between infected

herds (Wieringa-Jelsma et al. 2006). Although no published reports of the presence of BD

have been made in Indonesia, this could be due to a lack of testing rather than actual

freedom from the disease.

In this study there was no difference in the seroprevalence in different gender groups.

This finding is not surprising given the similar management of pigs of different genders and

the fact that the disease is not a sex linked disease.

107

5.4.3 Husbandry and biosecurity practices

Biosecurity has been defined as “the application of health controls and measures to

prevent the introduction and spread of new infectious agents into herds” (Barcelo and

Marco 1998). Commercial pig production requires a secure environment and excellent

hygienic conditions. Differences in standards of biosecurity between pig farms can affect

the potential risk for disease entry and transmission (Pinto and Urcelay 2003). The key role

of biosecurity is to prevent the introduction and spread of CSF (and other diseases) to pig

farms. During the epidemic of CSF inthe Netherlands in 1997/98 two factors were found to

be associated with the introduction of CSFV into herds. These included: the entry of

visitors to pig units without the provision of protective clothing and boots by the farm; and

drivers of trucks transporting pigs for the Pig Welfare Disposal Scheme (PWDS) using

their own boots, instead of boots supplied by the farm (Elbers et al. 2001). As with most

diseases, establishment of a strong biosecurity protocol is essential in maintaining a herd

free from disease. The challenge in Timor with village based farming practices is to

develop biosecurity measures that can be adopted by farmers which require minimal inputs.

As outlined in Chapter 3 farmers in West Timor rear pigs using a traditional system where

they are kept in small numbers in pens, tied up or are even allowed to roam freely. In such

environments it is difficult to adopt the typical biosecurity measures used by commercial

farms. To deal with this situation, the village could be considered as the unit of measure

which requires all pig households in the village to work collectively to protect the village

from the entry of disease. This requires farmers to cooperate to ensure introduced animals

are only obtained from certain farms or villages with high biosecurity levels.

Sanitary measures in these smallholding pigs are not well defined, and farmers are not

aware of the impact of poor sanitation on disease transmission, or the importance of good

sanitation in the prevention and control of disease. Differences in the scale of production,

108

standards of biosecurity, production inputs and marketing practices between pig farms can

potentially affect the risk of disease incursion and transmission. Appropriate biosecurity

measures, coupled with adequate management practices, are important to prevent the

introduction and spread of both endemic and epidemic infections (Barcelo and Marco 1998;

Amass and Clark 1999). Good biosecurity and management practices also have other

objectives such as reducing or eliminating the use of antibiotics, improving productivity

and achieving a higher health status of the pigs resulting in the production of healthier and

safer meat (Ribbens et al. 2008).

Good biosecurity is required to prevent the spread of CSF to pig farms. In addition,

the success of a good swine health-management program in commercial piggeries must

include the daily monitoring of housing and the pig’s environment, to ensure adequate

levels of hygiene and ventilation are provided (Pinto and Urcelay 2003). Ideally biosecurity

measures should also includethe availability of a disinfection foot-bath, a secure perimeter

fence, the restriction of the number of people and vehicles entering the farm, provision of

bird-proof netting on windows, providing on-farm protective clothing, having a suitable

quarantine facility for new introductions, and the restricted entry of replacement stock.

People working on intensive farms should not have contact with other pig farms, must wear

overalls and boots dedicated for on-farm use exclusively, and, preferably, must take a

shower before coming into contact with the animals (Casal et al. 2007). Visitors should be

restricted from entering piggeries, and a record of visits should be kept. Also, all visitors

should be subject to the same restrictions that apply to workers, and vehicles should not be

allowed to enter the farm. For this reason, it is necessary to have a dedicated parking lot

and a loading dock/bay for trucks (Casal et al. 2007). Although these methods are well

accepted and feasible in commercial enterprises, for small holder systems with minimal

infrastructure and inputs they are not practical or economically possible and there is a need

109

to develop simple biosecurity measures which can be practically adopted by small-holder

farmers.

Disposal of affected and diseased pigs is important and subsequent decontamination

of affected areas is vital for the control of CSF in intensive piggeries. Pigs infected with

CSF can excrete virus from the respiratory, urinary and alimentary tracts, so consequently

contaminate their immediate surroundings which can result in infection of other pigs

introduced to these environments (Edwards 2000). The CSFV can survive for varying

periods in manure, with its infectivity lost in approximately 15 days (Have 1984). In a

slurry (a mixture of faeces and urine, water, bedding material and uneaten feed) the virus

has been shown to survive for at least 70 days at 17°C, and for 84 days at 4°C (Haas et

al.,1995). In pens contaminated with secretions and excretions of infected pigs, CSFV can

survive for at least 10 hours at 22°C (Ribbens et al. 2004). During winter when

temperatures decrease, CSFV can survive longer and pens may contain virus in excreta and

bedding for at least 4 weeks (Harkness 1985). Moreover, contaminated pens can contain

infectious virus for a few days before the virus is inactivated (Artois et al. 2002). The

survival time in various types of water has been reported to vary from 6 to 24 days at 20°C

(Pagnini et al. 1984). Given the reasonably high temperatures found in West Timor, and the

open air nature of the piggeries allowing access by sunlight (UV light), it is likely that virus

present in the environment will be quickly inactivated. Consequently a short period of

spelling between batches of pigs may be sufficient to remove any virus surviving in the

environment. However other risk factors present in small holder herds in West Timor, such

as swill feeding, contact between pigs and contact with feral pigs remain and have the

potential to reintroduce the virus to naïve pigs.

Climatic factors, such as low or high environmental temperatures, high wind speed,

and wet floors resulting in the requirement for increased intake of energy and the presence

110

of diseases, can affect the performance of pigs (Shrestha et al. 2002). Therefore, intensive

piggeries should provide protection against environmental stresses, good sanitation and

hygienic conditions, sufficient space, minimise feed wastage and be as inexpensive as

possible to run (Lekule and Kyvsgaard 2003). However, pigs in West Timor are raised

under various husbandry practices including free range feeding, tethering, and confinement

and husbandry practices for intensive piggeries are often not suitable or practical for such

environments. Free range grazing is practiced mainly by small farmers in rural areas where

pigs are fed mostly on grass, agricultural by-products, and kitchen scraps. In addition, any

housing provided on Timor is characterised by a lack of protection against the wind, lack of

bedding materials, poor sanitation, small area and wet floors leading to food wastage,

physical damage through fighting, predisposition to rapid disease transmission, worm

infestation and the potential for heavy losses of pigs (Figures 5.1 to 5.4). However,

surprisingly in this study it was found that biosecurity practices, carcasses disposal methods

and type of housing were not significantly associated with antibodies to CSF. This may be

due to the generally similar management and husbandry standards adopted by pig-farmers

throughout West Timor.

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Figure 5.1 Pig house made from easily accessible materials in Kota Kupang

Figure 5.2 Pig tethered in the house-yard of a pig owner

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Figure 5.3 Pig house in Belu

Figure 5.4 Raised pig house in Belu with a free roaming pig

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5.4.4 Pig feed and source of drinking water

Swill feeding is important in the introduction of CSF into a previously disease-free

area as the virus can survive for long periods in a variety of meat products (Edwards 2000).

Consequently it has been recommended that swill feeding should be banned or be strictly

controlled to ensure that only properly heat-treated materials are fed. The virus can be

inactivated in swill if it is maintained at a temperature of at least 90°C for at least 60

minutes with continuous stirring; or at a temperature of at least 121°C for at least 10

minutes at an absolute pressure of 3 bar (OIE 2010). It has also been recommended that the

public and the pig industry need to be aware of the risks from imported pig meat products

(Paton and Greiser-Wilke 2003), however this is not likely to be a problem in West Timor

where no known importation of pigs or pig products occurs, other than with Timor Leste.

Feeding pigs with feed wastes from restaurants has been reported to be a source of CSF

outbreaks in both fattening farms and small holdings in Barbados (Hutson 1974). The

challenge with small-holder farms is that swill feeding is utilizing an inexpensive (usually

free) food source and is an important protein and energy source for the pigs. Education of

farmers on the appropriate processing and handling of swill will enable this valuable food

source to be utilised while minimising the disease potential from its use. However, based

on the current data analysis swill feeding was not found to be associated with the presence

of antibodies to CSFV in West Timor. This may be due to the common adoption of this

practice in West Timor, or the importance of other factors in the distribution of CSFV

within the region. It is likely that swill feeding plays some role in the distribution of virus

between herds, especially if products from infected pigs are fed to other pigs.

Pigs need water in order to fulfill a number of physiologically significant functions,

namely thermoregulation, mineral homeostasis, excretion of metabolites, achievement of

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satiety and behavioural purposes (Mrozet al. 1995). However water can be a potential

source of CSFV as the virus can survive in water maintained at 20°C for 6 to 24 days

(Pagnini et al. 1984). In this study the source of water was not statistically associated with

the presence of CSFV and it is likely that other factors are more important in the

transmission of virus in West Timor.

Nutrient availability has the potential to affect the immune system, and this in turn

helps protect tissues from disease-promoting factors (Kubena and McMurray 1996). In

sows, the difference between the energy and nutrient requirements and their intake will

determine the level of anabolism or catabolism of body tissues (Booth 1990) and growth

rate and body composition (Kirkwood and Aherne 1985). Body composition and its

relationship with reproduction is well established in humans (Frish 1988), as well as in

other animal species including pigs (King 1987). In pigs the body composition has an

important impact on the production and health of a herd (Charette et al. 1996). In sheep,

beef, and dairy cattle body condition score (BCS) is used as a subjective method to

determine the body reserves of these animals (Pryce et al. 2001). In cattle, BCS has been

related to reproductive performance and milk yield, however in pigs these relationships are

not reliable (Knudson et al. 1985), and the benefits are debatable (Dial et al. 1992).

Nevertheless, by the use of data derived from live weight and back-fat measurements, the

BCS can be more useful (Charette et al. 1996). However in the current study this was not

possible. With respect to the situation in West Timor, the BCS of pigs varied widely from

poor to good. The poor condition of some pigs is most likely to have arisen from poor

nutrition and management and the presence of certain diseases, in particular those affecting

the gastrointestinal system including ascariasis resulting from infection with Ascaris suum

(Stephenson et al. 1980). Nutrition and management have a significant impact on the body

condition of pigs (Corwin and Stewart 1999) as does the presence of disease. However,

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based on the data collected during this study, there was no association between BCS and

seroprevalence to CSF in West Timor.

5.4.5 Reproductive management

Natural mating can be an effective way for the transmission of CSF. Infection via

infected semen can be an important route of transmission of the virus (de Smit et al. 1999a;

Choi and Chae 2003). Use of artificial insemination (AI) can reduce this potential for

disease transmission, provided semen is collected from animals free from CSF (Floegel et

al. 2000). However in this study there was no significant difference between the prevalence

in naturally mated and artificially inseminated piggeries. This is likely to have arisen from

the low adoption level of AI (27.4%-Chapter 3) and the likely exposure of inseminated pigs

to virus through other means such as wild pigs or contaminated swill.

5.4.6 Movement of pigs

The movement of pigs, in particular that associated with the trading of pigs, has both

positive and negative impacts on a population. There are benefits to increasing the size of

the population through immigration and introduction of improved genetics if introduced

pigs are of superior quality to the local pigs. However there are significant risks through the

introduction of new diseases or new strains of organisms to the importing herd (Lindstrom

et al. 2010; Fevre et al. 2006). The purchase of pigs from markets or from different

breeding farms has been shown to pose a significant risk to herds through the potential

introduction of diseased animals (Beals et al., 1970; Pinto and Urcelay 2003). Furthermore

there is the potential for the mixing of animals from a wide geographical area, and this,

along with the stress of relocation, can provide an ideal opportunity for the spread of

infection (Dahle and Liess 1992; Moennig et al. 2003). The movements of pigs or

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contaminated feed and fomites have been shown to be significant risk factors for the spread

of CSF (Dahle and Liess 1992; Elbers et al. 2001; Terpstra 1987). In the current study it

was found that introducing pigs during the 12 month period preceding the survey was

strongly associated with infection (P =0.01; OR=4.7; 95% CI 1.5, 15.7). It would be

assumed that the introduced pigs have also introduced CSFV or new strains of the virus to

the importing herds. Implementation of a closed herd system, which can be achieved in

intensive piggeries and will reduce the likelihood of introducing the disease, is difficult to

implement in village level systems due to the small number of pigs owned and hence poor

selection pressure for replacement animals.

5.4.7 Control strategies for Classical Swine Fever

Classical Swine Fever is endemic in West Timor as outlined in Chapter 4. Animal

trade may contribute to the spread of CSF, as West Timor has major local markets within

districts and pigs are traded across the border with the neighbouring country of Timor Leste

(personal communication from farmers in Belu). In addition, as a large percentage of the

pig production in this region is in smallholder farms, with many pigs allowed to roam

freely or kept in facilities with poor isolation capability, poor management, husbandry and

biosecurity may contribute to some outbreaks of CSF. These methods of keeping pigs were

considered to be significant in the transmission of CSF in Hong Kong (Ellis et al. 1999).

Low levels of veterinary infrastructure (cold chain system, public electricity, transportation,

and telecommunications) might also have exacerbated infectious disease problems in West

Timor. Poor diagnostic facilities and a lack of disease reporting systems may have also

allowed the disease to spread largely unchecked due to the low level of disease recognition

associated with limited human resources including veterinarians and animal health workers

(personal communication Dr. Maria Geong, Dinas Peternakan NTT).

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Provision of suitable veterinary services is important for the early detection,

surveillance and treatment of animal diseases, including diseases of public health

significance. Veterinary Services can also provide livestock owners with information,

advice and training on how to prevent, control or eradicate disease. Therefore, by having

access to veterinary services, farmers receive a number of benefits which can improve the

health and well-being of their animals as well as resulting in a financial gain through the

absence of disease. Although animal health posts (Poskeswans) are present in West Timor

there are only a limited number staffed by veterinarians and field animal health workers

(personal communication Dr. Maria Geong, Dinas Peternakan NTT).

The Province of Nusa Tenggara Timor (NTT) has been categorized as a suspected

area for CSF, and a control program has been set up as a national priority (Satya and

Santhia 2009). These authors described the control measures to be implemented based on

the status of CSF. These include:

Implementation of vaccination with a goal to vaccinate at least 60% of the pig

population with officially recommended vaccines. The vaccination is carried out by

private and government veterinarians under the direction of government

veterinarians. The supply of vaccine for small pig farms is subsidised by the

government.

The prohibition of the exportation of pig and pig products out of Indonesia

Implementation of serological surveillance

Prohibiting the movement of pigs and pig products from infected areas.

Implementing intensive serological surveillance for the early detection of any

disease introduction.

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Several strategies have been used to control CSF in different regions or countries. For

example, eradication of infected and suspected herds with massive slaughtering of pigs and

herds has been adopted in previously CSF free areas in Europe. Such programs have

significant economic and ethical disadvantages (Saatkamp et al. 2000), particularly in

endemic regions. In contrast vaccination has been adopted in most areas where the disease

is endemic (Suradhat et al. 2007; van Oirschot 2003). However the use of live attenuated

vaccines is not recommended for an eradication program (Moennig 2000) due to the

presence of potentially infectious or mutant strains in the field (Curtis et al. 2002).

Recombinant subunit vaccines against CSF (marker vaccines) have recently been

developed (de Smit et al. 2000). These vaccines offer the advantages of inducing an early

and long lasting protection (Barrera et al. 2010). Most attenuated vaccines are based on the

China-strain (C-strain) of lapinized CSFV. C-strain vaccines were, and still are, being used

throughout the world, including Indonesia, for the control of CSF in domestic pigs

(Moennig 2000). This strain has also been used experimentally via the oral route (baits) to

induce immunity in wild boar to aid in the control of the disease (Kaden et al. 2000).

Vaccination protects a population of pigs by providing protective immunity against

infection. Vaccines are widely available and the commercially available modified live CSF

vaccines are able to induce protective levels of immunity (Suradhat et al. 2007). When the

number of unvaccinated pigs in a population is high, these animals are potentially exposed

to infection from infected or carrier pigs. The use of vaccine in the control of CSFV

infection has been a useful tool in the eradication of this disease (Terpstra 1991). However,

the use of live vaccines, other than marker or differentiating infected from vaccinated

(DIVA) vaccines, has a major disadvantage where the antibody response they induce

cannot be differentiated from that of natural infection with field virus (Van Oirschot 2003).

Consequently with vaccines used in Indonesia (C- strain) it is not possible to differentiate

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vaccine induced immunity from immunity resulting from natural infection. In the current

study, based on the data analysis, farmers which had vaccinated their pigs against CSF were

2 times more likely to have seropositive pigs than those who had not vaccinated their pigs

(P=0.035; OR = 2.3; 95% CI 1.1, 5.1). This is not surprising as the vaccine induces

protective immunity which is detectable by the diagnostic ELISA used in this study. It is

widely accepted that vaccination against CSF is an important step in the control of the

disease, and the challenge in West Timor is to increase the level of acceptance and adoption

of vaccination by farmers.

5.5 Conclusions

This study has revealed three potential risk factors for the presence of antibodies to

CSFV in West Timor: the introduction of pigs in the 12 month period preceding the survey;

keeping goats; and having vaccinated pigs. Even though the other factors were not

statistically significant in terms of being associated with the presence of antibodies to

CSFV in West Timor, it does not mean that these factors are not important. The relatively

uniform management practices adopted by farmers in West Timor could have meant that

some factors were identified as not significant when they could play an important role in

the disease. In the control of CSFV in West Timor it is likely that all potential factors

should be evaluated and changes made to those which are economically and

epidemiologically important.

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CHAPTER SIX

GENERAL DISCUSSION

6.1 Introduction

Pigs have both a cultural and an economic role in societyin West Timor. They have

an important function as a source of income and are also commonly sacrificed in traditional

celebrations. As with other islands in NTT, people in West Timor have strong family

relationships. At family gatherings, such as occur with traditional or religious ceremonies,

pigs are often slaughtered for the occasion and family members also frequently take meat

home from such events. Pigs used in these celebrations are usually provided by the family

who coordinates the event, but occasionally pigs are provided by other family members

potentially resulting in the transport of pigs from villages far from the celebration place.

The number of pigs slaughtered each year in West Timor is high. In 2006 237,179 pigs

were slaughtered representing 45% of the population (Provincial Livestock Services of

NTT 2010). Pigs also play an important part in the financial well-being of farmers and are

often sold to pay for school fees, to provide funds for building houses or as capital in

emergency situations. This is highlighted in the current survey where 80.8% of the

surveyed pig households kept pigs for emergencies. Pigs also play an important role as a

source of protein for households and in this study 9.6% of households kept pigs for their

own consumption.

Pig farms in West Timor are mostly non-commercial, smallholdings and are

therefore not run intensively with each pig household owning only between 1 and 10 pigs.

However, the commercial pig industry in NTT is growing and there is the opportunity for

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smallholder pig farmers to become involved in this market. The increasing demand for pigs

and the concurrent increase in the pig population is resulting in the development of the pig

industry and increasing market opportunities, both locally and regionally, for pigs and their

meat products. This has the potential to improve income for farmers and farm productivity

in NTT (Craiget al. 2010).

There are significant challenges faced by traditional pig farmers through poor

management, disease and a lack of basic knowledge about husbandry and production of

pigs. In respect to disease, farmers in West Timor have been concerned about CSF for

many years since it first appeared in 1998. Classical swine fever is a highly contagious viral

disease that infects both domestic and wild pigs (Lindenbach and Rice 2001), with high

morbidity and mortality, especially in young animals (Moennig and Greiser-Wilke 2008).

Infection of pigs can result in an acute fatal disease with mortalities up to 100% in a

susceptible population, however it similarly can result in a chronic form of disease which

may be difficult to detect due to mild signs associated with reduced productivity (Dahle and

Liess 1992). The disease is classified in the A list of infectious diseases of most importance

for international trade by the OIE because it is a highly contagious disease and is difficult to

control in areas with a high density of domesticated or wild pigs (Anonymous 1999).

In West Timor vaccination has been adopted since 2000 (Personal communication

Dr. Maria Geong, Dinas Peternakan NTT) in an attempt to minimize the infection. Prior to

the study outlined in this thesis the prevalence of CSF had not been estimated in West

Timor based on sound epidemiological sampling and little was known about risk factors for

the disease in West Timor. Therefore, this study was designed: to describe the village level

pig system in West Timor including the husbandry and management practices adopted; to

investigate the distribution and seroprevalence of CSF in West Timor in small holder

farms; and to identify factors associated with seropositive animals or herds.

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Educational background plays an important role in the production, husbandry and

management of livestock. Marenya and Barrett (2007) reported that in Kenya smallholder

farmers with secondary education adopted new technology and practices compared with

farmers with only a primary education level. In North America and Europe education of

farmers through agricultural and extension material has played an important role in

providing essential technical and managerial skills for young people working in farming

and related agricultural areas (AIAEE 2010). Extension involves the communication of

information to help farmers form sounds opinions and make good decisions (Australasia

Pacific Extension Network 1999; Black 2000), and includes both public and private sector

activities relating to technology transfer, education, attitude change, human resources

development, and dissemination and collection of information (Marsh and Pannell 1998).

However in West Timor there is a lack of suitable material for farmers and material on

sustainable farming practices, management and care of animals and diseases requires

developing in a format acceptable by local small-holder farmers.

In order to achieve a good level of production, farmers need to have sufficient

knowledge and skills about good farming practices. Although in this study the level of

education of farmers in West Timor was reasonable, with 60.8% having completed senior

high school, only 0.4% of farmers had attended or undertaken any formal post-secondary

animal training. This may be because pig-rearing is not the main occupation of most

farmers interviewed but an ancillary side-line.

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6.2 Prevalence of CSF in West Timor.

In this study the overall seroprevalence of CSF in West Timor was 18.7% (95% CI:

15.9-21.8%). The prevalence in the district of Belu (21.3%: 95% CI 17.2-25.9%) was

slightly higher than that of Kupang (16.1%: 95% CI: 12.4-20.3%). The difference in the

seroprevalence between subdistricts and villages could be influenced by the incidence rate

and duration of the disease (Thrusfield 2005), the course of infection (acute or chronic)

(Artois et al. 2002; Mengeling and Cheville 1968), the virulence of the infecting virus

(Dahle and Liess 1992), biological variation between pigs (Gardner and Blanchard 1999),

population density between districts (Mintiens et al. 2003), or severity or stage of disease

(Pfeiffer 2010). Antibodies to CSFV may not be detected in serum samples if the disease is

in the incubatory phase as antibodies are only detectable two weeks after infection and then

persist for life (Moennig and Greiser-Wilke 2008).It is possible that some clinical cases of

CSF may have died, particularly with the acute form of the disease, before a serological

sample was collected resulting in a reduced seroprevalence. Given the movement of pigs

through West Timor and the similar type of pigs found throughout the region it is unlikely

that biological variation accounted for the difference in the prevalence for the two sampled

districts.

This study identified three risk factors in the multivariable logistic regression model

that were associated with the presence of antibodies to CSFV in West Timor: the

introduction of pigs in the preceding 12 month period, the keeping of goats, and a history of

vaccinating pigs. In respect to the introduction of pigs, the purchase of weaner pigs from

different breeding farms or from markets has been shown to have a high risk of introducing

the virus into susceptible populations (Beals et al. 1970). Pigs sourced in West Timor may

have come from other villages or through markets and potentially have the opportunity to

have contact with many other pigs, some of which may be excreting the CSFV. Others have

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shown that a high density of sheep and/or goat herds within 3 km of the pigs is a riskfactor

for infection in breeding pigs (Loeffen et al. 2009). In West Timor on smallholder farms

the pigs and goats have the potential to be in close contact as most goats are free roaming.

This close contact would allow for the potential transmission of Border Disease from the

goats to the pigs, however there has been no published work to confirm the presence or not

of Border Disease in Indonesia. Further work is required to determine if Border Disease is

present in Indonesia and if so how frequently it is being transmitted to pigs.

Vaccination is aimed to induce not only clinical protection but also to stop

transmission of infections within and between herds by inducing herd immunity (Anderson

and May 1991). However vaccination with standard vaccines results in antibodies which

cannot be differentiated from those induced by natural infection (Bouma et al. 2000;

Tignon et al. 2010; Van Oirschot 2003). In this study although only a low proportion of

pigs had been vaccinated (9.9%) it is not surprising that a history of vaccination was

strongly correlated with a seropositive response.

6.3 Impact of CSF in West Timor.

Classical swine fever results in both direct and indirect losses to pig producers.

Direct losses include deaths and decreased production, productivity and reproduction in

pigs and the additional expenses for the treatment, control or prevention of the disease.

Indirect losses include losses from any trade bans or restrictions on the sale of products,

additional costs through any biosecurity measures implemented and stresses and strains on

the pig producers (Niemi et al. 2008; Saatkamp et al.2000). In countries with an intensive

pig production and a high wild boar density, CSF can have a significant impact on

agriculture and forestry (Kaden and Lange 2004). The economic impact from outbreaks of

CSF in the Netherlands in 1997 was estimated to be US$ 2.3 billion (Artois et al. 2002;

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Clavijo et al. 2001; Meuwissen et al. 1999). Moreover, during the epidemic of CSFV in

Europe from 1997 to 1998, direct and indirect losses were estimated at €2.2 billion,

excluding losses caused by CSF in the wild boar in the forests (Terpstra and de Smit 2000).

In West Timor an economic evaluation of the impact of CSF to either the commercial or

small-holder farmer has not been undertaken. Such an evaluation is required and is essential

to ensure cost-effective treatment, control and prevention protocols are developed.

6.4 Modes and routes of transmission of CSFV

Knowing the modes and routes of transmission of CSFV are essential in developing

effective control programs for CSF. Transmission of CSFV can be through direct contact

with infected pigs or by ingestion of products from infected pigs (AusVetPlan 2009;

Karsten et al. 2005; Paton and Greiser-Wilke 2003; Stegeman et al. 1999). Whereas,

indirect transmission may occur via people, wild animals and inanimate objects, animal

products and by-products (AusVetPlan 2009), vectors, semen and embryos, vehicles and

other contaminated materials (Elbers et al. 1999; Moennig et al. 2003). The virus is

transmitted mainly by the oro–nasal route, through contact with mucous membranes or skin

abrasions, insemination, or percutaneous blood transfer (e.g., reuse of needles,

contaminated instruments) (Moennig and Greiser-Wilke 2008). The movements of infected

pigs, contaminated trucks, swill feeding, contaminated clothing and footwear of people

have been suggested as the most common means for transmitting the virus between herds

(Dahle and Liess 1992; de Smit et al. 1999a; Stegeman et al. 1997; Terpstra 1987). People

can play an important role in the distribution of virus, in particular farmers, inseminators,

pig handlers, and veterinarians. The virus can also be distributed through airborne

transmission (Hughes and Gustafson 1960; Laevens 1998; Laevens et al. 1998; Laevens et

al. 1999; Mintiens et al. 2000; Terpstra 1987), birds (Hughes and Gustafson 1960) and

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rodents (Terpstra 1987). Airborne transmission is particularly important in countries with a

high density intensive pig industry; however airborne transmission is unlikely to be a major

route for disease transmission in West Timor.

In West Timor there are several possible routes of transmission of CSFV. As with

other countries the movement of infected pigs, which is important for both trade and

cultural practices, is significant. Pigs are sold both in markets as well as purchased directly

from farms, however market selling in this study was infrequent with only 10.8% of

farmers selling pigs at markets. At markets pigs with different health statuses and origins

are mixed together without any health control. This practice can enable CSFV to be easily

transmitted from infected to susceptible pigs. Elbers et al. (1999) outlined that the

movement of pigs, which were incubating the disease or which were persistently infected,

was an important source of transmission of CSFV, particularly at the start of an outbreak.

Secondly swill feeding is practiced commonly in West Timor with 91.3% of farmers

adopting this practice. In this study it was found that many farmers failed to adequately

treat the swill fed to pigs and consequently there is the potential for virus to be transmitted

to pigs. Swill feeding has been banned in many countries because it is a potential source of

CSFV, as well as other serious diseases such as FMD (Edwards et al. 2000). However in

smallholder situations swill is a valuable and inexpensive source of protein. Thirdly,

artificial insemination (AI) offers several advantages including not requiring a boar to be

kept and the potential to introduce improved genetics to a herd. However AI requires

necessary expertise for performing the procedure and in detecting a female is in oestrus and

there is the potential for CSFV to be transmitted through the semen if collected from

infected boars (de Smit et al. 1999a; Floegel et al. 2000) or indirectly through contaminated

equipment, fomites or clothing and footwear of the inseminator. Maes et al. (2008)

suggested that the best strategy to prevent AI-transmitted diseases was to use boars from

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specific pathogen free herds (SPF), to monitor the animals and semen regularly for disease,

and to maintain a donor herd of very high biosecurity. This is currently not feasible in West

Timor, due to the expense and a lack of suitable pigs to be the parent stock for an SPF herd,

however a Government funded breeding herd has been established (Livestock Breeding and

Animal Feed Production Unit in Tarus, Kupang). The challenge in situations such as West

Timor is to develop suitable and practical methods to control CSF that are feasible for

adoption by small-holder farmers.

The distance between herds has been reported to be a risk for CSFV transmission,

with herds within a half kilometre radius from an infected herd being at significant risk of

infection (Laevens 1998; Mintiens 2000; Mintiens et al. 2003; Staubach et al.1997;

Stegeman et al. 2002). Crauwels et al. (2003) and Terpstra (1987) also found that the larger

the size of neighbouring herds the greater the risk of a herd becoming infected. Boklund et

al. (2008) predicted that, in Denmark, CSFV could be transmitted from domestic pigs to

wild pigs that were located within a 5 km radius of the infected herd. During the CSF

epidemic in the Netherlands in 1997 and 1998, trucks also played a major role in the

dispersion and transmission of CSFV. In West Timor although there are no large scale

intensive piggeries, small holder units are in close proximity within each other in villages.

In this management system there is the potential for direct and indirect transmission of

virus from one herd to another.

6.5 Eradication of CSF

There have been numerous different measures adopted to control outbreaks of CSF as

outlined in Chapter One. Firstly, slaughter of infected herds has been implemented in

combination with vaccination in some countries. In West Timor destocking (slaughtering)

cannot be implemented due to the significant financial implications of this practice.

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Furthermore no compensation is available in West Timor for destocking as is present in

other countries. Instead in NTT vaccination of healthy pigs is implemented. However if a

disease free zone for CSF is planned for West Timor, slaughter of infected commercial

herds in combination with vaccination may need to be considered. Before such measures

can be implemented, suitable control programs need to be implemented and a cost/benefit

analysis undertaken to evaluate the financial benefit of implementing such programs.

Secondly, protection and surveillance zones around infected herds need to be

established at 3 and 10 km radius respectively. In these zones the movement of pigs needs

to be restricted to prevent any further virus spread. This control measure has been widely

implemented in Brazil and European Union countries (Blome et al. 2010; Edwards et al.

2003; Fritzemeier et al. 2000) but would be difficult if not impossible to implement in

smallholder situations in West Timor.

6.6 Control program for CSF in West Timor

In countries where CSF is endemic, such as Indonesia, regular vaccination

campaigns, accompanied by routine diagnostic procedures, are often recommended as the

best methods for the control of the disease (Moennig and Greiser-Wilke 2008;Suradhat et

al. 2007;Van Oirschot 2003). It is also recommended that continuous surveillance programs

should be designed and implemented as part of any control program. Surveillance needs to

be targeted to the pig population which presents the highest risk of infection (for example

farms that feed swill, farms where pigs are reared outdoors or farms with wild pigs in close

proximity) (OIE 2008). This is designed to keep the number of infected herds as low as

possible, with the effectiveness of a surveillance program being measured by the number of

infected herds at the end of the high-risk period (time between virus introduction and

detection of the first case) (Klinkenberg et al. 2005). In order to control CSF in West Timor

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three areas/factors need to be considered: monitoring and serological surveillance combined

with vaccination; knowledge and understanding of the husbandry and management of pigs;

and management of risk factors for the disease.

It is important to implement a continuous monitoring and participatory surveillance

system which involves all pig-owning households, village people and animal health

workers and veterinarians. The objectives of participatory surveillance (Thrusfield 2005)

are: to rapidly detect an outbreak of CSF in high risk areas; to assess the health status of a

defined pig population; to define priorities for the control and prevention program; to

evaluate the CSF control program implemented; and to confirm the absence of disease in

particular areas for the purpose of establishing free, protection, and surveillance zones.

Serological surveillance in West Timor should include both passive and active

surveillance. Although passive surveillance has weaknesses including potential biases, not

being able to provide estimates of seroprevalence and potentially resulting in

underestimates of disease frequency (Thrusfield 2005), it is the first stage in identifying

new and emerging diseases. Passive surveillance establishes good relationships between

farmers and veterinarians; facilitates informal intelligence on animal health; and involves a

lower cost than active surveillance. In contrast, in active surveillance biases can be

minimized because surveillance is based on well-designed surveys. To give the best results

these two methods should be combined to maximise the quality and quantity of information

collected.

Vaccination against CSF was developed in the 1960s (Terpstra 1991) and now there

are a number of highly effective live attenuated vaccines (Biront and Leunen 1988), and it

is the most common means used for prevention and control of the disease in endemic areas

(Suradhat et al. 2007). Several conventional vaccines against CSF have been developed that

claim to be safe and effective in inducing protection of pigs against clinical disease and

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reducing the shedding of CSFV (Van Oirschot 1992). The protection induced by

vaccination varies widely depending on the type of vaccine strain used. The Chinese (C)

strain vaccine is generally accepted to be very safe in pigs of all age groups, providing

complete protection, i.e. sterile immunity in vaccinated pigs (Suradhat et al. 2007). The C

strain vaccines usually induce detectable neutralizing antibodies 2 to 3 weeks following

primary vaccination (Precausta et al. 1983; Terpstra et al. 1990), and they are safe when

used on pregnant animals (Moennig 2000). A single vaccination with the CSF-modified

live vaccine (CSF-MLV), including C strain (both lapinized and tissue culture derived) and

Japanese guinea-pig exaltation-negative (GPE) strains, has been shown to induce complete

protection against infection as early as 5 to 6 days after vaccination (Moennig 2000;

Suradhat et al. 2007) and the animals were immune throughout their economic life (6 to 18

months) (Aynaud 1988; Ferrari 1992; Kaden and Lange 2001;Moennig 2000; Szent-Ivanyi

1977; Terpstra et al. 1990). Terpstra (unpublished results cited by Van Oirschot 2003)

observed that sows vaccinated during a field campaign and subsequently challenged 6 to 7

years later, still remained healthy. The disadvantage of this type of vaccine is that animals

vaccinated with vaccines derived from the C-strain cannot be distinguished from animals

that have recovered from natural infection (Suradhat et al. 2007).

In contrast the E2 vaccine is a marker vaccine, allowing differentiation between

naturally infected and vaccinated pigs (Bouma et al. 1999; Suradhat et al. 2007). This

vaccine is based on the envelope glycoproten E2 (Van Zijl et al. 1991) and induces a

neutralizing antibody response in pigs (KoÈnig et al. 1995; Van Oirschot 2003; Van Rijn et

al. 1996; Van Zijl et al. 1991). During an infection with field virus antibodies are produced

against all viral proteins, although they do not all neutralise the virus. Consequently

detection of antibodies which are not directed against the E2 glycoprotein should be

indicative of a serological response to natural infection with CSF (Suradhat et al. 2007).

131

However it may take a longer time (at least 2–3 weeks) following vaccination or require

more booster vaccinations to induce complete protection against the virus (Suradhat et al.

2007). However, the vaccine has been shown to be stable for at least 18 months, and still

retain full potency (Bouma et al. 1999).

In NTT generally and in particular West Timor, vaccination has been practiced as the

main control program against CSF for many years which was initiated in 2000 (personal

communication with Dr. Maria Geong, Dinas Peternakan NTT). However, based on the

results of the current survey few households (5.4%) had vaccinated pigs. The reasons given

for not vaccinating pigs included: the owners used natural medicines; they were not at

home when the vaccinating team came to their village; or they did not believe in

vaccination. It is essential that farmers understand what vaccination is and the benefits of

vaccination before a vaccination program is likely to be successful. Therefore it is

important that suitable educational material is developed and disseminated before a

vaccination campaign is implemented. In the current survey it was evident that surveyed

households had little knowledge about the disease and methods to control it, and this deficit

in knowledge needs addressing.

With respect to husbandry and management, good farming practices are required to

minimize infection on farms. Pig households need to be encouraged to adopt good

husbandry and management practices including cleaning of pens, feeding only proper

treated swill and appropriate disposal of carcasses. It is essential to implement suitable

biosecurity measures to minimise the transmission of CSF. Moennig and Greiser-Wilke

(2008) suggested that a system for the registration and identification of all holdings and

pigs is required in order to eradicate the disease. The pig owners interviewed in this study

conducted few, if any, on-farm biosecurity practices. This is because the households

interviewed generally raised only a few pigs, pig-rearing was not their main occupation and

132

they had little knowledge on disease transmission or how to prevent disease. Terpstra

(1991) recommended that farm buildings are thoroughly cleaned and disinfected regularly,

however this is often impractical on small-holder farms which have minimal facilities or

the means to purchase the necessary disinfectants. However disposal of pig faeces, which

can be used as fertilizer on gardens, and spelling/rotation of pig pens or areas where pigs

are tied up will help to reduce the dissemination and reinfection of pigs with a range of

diseases including CSF and ascariasis.

It is important to identify risk factors for disease and remove these for the effective

control of CSF. Smith (1982) identified three important factors involved in the transmission

of CSFV: characteristics of the host; characteristics of the pathogen; and the degree of

effective contact between the host and the virus. To manage risk factors information is

required on: the temporal and spatial distribution of previous outbreaks; movement of pigs;

and the demographics and distribution of pigs. Consideration should be given to the

specific characteristics of the epidemiology of CSF which include: the role of swill feeding

and the impact of different production systems on disease spread; the role of semen in the

transmission of the virus; the lack of pathognomonic gross lesions and clinical signs; the

frequency of clinically inapparent infections; the occurrence of persistent and chronic

infections; and variability in the genotype and virulence exhibited by different strains of

CSFV (OIE 2008).

In this survey almost all farmers fed swill to their pigs, with 34.2% of respondents not

usually cooking the swill prior to feeding it to pigs.It is well documented that swill feeding

can lead to the introduction of CSFV into pig-rearing areas and consequently this practice

has been either totally banned (Fritzemeier et al. 2000), or processing guidelines enforced

(Edwards et al. 2000). Swill feeding, suboptimal on-farm biosecurity and quarantine

practices, and poor pig carcass disposal systems may also compromise the health status of a

133

pig herd, rendering them more susceptible to the entry of other diseases as well as CSF

(Schembri et al. 2010).

The movement of pigs on to and off farms in the surveyed areas in the 12 month

period prior to the survey was reasonably common with 12.1% of the interviewed

households introducing new pigs into their herds in the 12 month period preceding the

survey. Of the pigs acquired 20% came from other districts. This allows for significant

distribution of infection, as well as the potential for virus to be shed along the route and

infect susceptible pigs(Schembri et al. 2010). The lack of knowledge on pig movements in

West Timor presents a limitation to the identification of likely sources of infection and it is

important to undertake more research to track animal movements. Markets are ideal

premises for the transmission of CSFV as livestock from many different sources are

brought together for a short period of time, before returning to their place of origin or

moving to new premises. Such premises pose particular problems for disease control, as

they are potential sources for the dissemination of disease agents over wide geographical

areas. This is one area which requires further investigation in West Timor, as is the

development of an identification system for pigs to enable trace-forward and trace-back of

animals and a permit system controlling movement of animals.

Routine cleaning and disinfection of fomites should be implemented as part of

normal management procedures to prevent the transmission of CSFV onto farms (Owen

1995). Pathogens can survive on premises, and in particular in those areas associated with

the housing of new-born and young animals, pregnant females and suckling mothers

(Fotheringham 1995) and regular cleaning and disinfection of such areas can help reduce

the environmental burden of pathogens. However, this is not suitable for small farms in

West Timor but could be adopted for larger units or commercial farms in West Timor.

134

Biosecurity is important in the daily management of pig herds to avoid infections

and subsequent costs associated with disease (Ford 1995). Entry to and exit from

contaminated premises by animal health personnel, workers, owners, wildlife, insects,

domestic animals and rodents presents a risk of disease spread which demands constant

attention. The least expensive means of controlling and eliminating the risk of introducing

pathogens involves maintaining constant biosecurity programs (Ford 1995). On farm

biosecurity is referred to as the application of health controls and measures to prevent the

introduction of new infectious diseases into herds and to avoid their spread (Barcelo and

Marco 1998). In order to reduce the risk of introducing CSFV onto farms, both small-

holder and large scale farms need to increase their on-farm biosecurity. As CSFV can be

transmitted by both indirect and direct contacts, and the risk of disease introduction is more

likely to be influenced by aspects of management and biosecurity, it is important for farms

to develop, implement and practice good on-farm biosecurity. Biosecurity is essential in

preventing contact between healthy non-infected animals from infected ones (Thrusfield

2005), and encompasses cleanliness, disinfection, reduction of exposure, management of

personnel, and ensuring the tracing of animals (England 2002). As discussed earlier the

challenge with small-holder situations is to develop measures that are cost-effective,

practical and feasible for adoption.

In order to effectively and efficiently control and eradicate CSF from West Timor

several factors need to be considered. Firstly the implementation of control and eradication

campaigns needs to be supported by well equipped and skilled veterinary services (ie

infrastructure). Secondly, there is a need for adequate financial support, well established

legislation and sufficient compensation. Thirdly, public awareness and understanding of the

benefit of the control program is required. Control programs for CSF are not stand alone

programs and require the involvement and consideration of factors which affect the public,

135

farmers, government and other stakeholders. Farmers for instance need to be informed

about the benefits of the control program and its process so that the program implemented

is well understood, particularly given that any control program is both time consuming and

requires significant effort by farmers. For example, eradication of CSF in the UK required

an intensive three year eradication program (Meldrum 2003), and eradication from the USA

lasted 15 years (1961 to 1976) (Wise 1986). Therefore, the Government, farmers,

stakeholders and other parties should work together to ensure the successful control and

eradication of CSF. The eradication of CSF from West Timor and eventually NTT is the

ultimate goal, however given the results highlighted in this study, in particular a small-

holder based management system, extensive unrestricted animal movements, poor farmer

knowledge about CSF, poor uptake of vaccination and the presence of many risk factors for

the dissemination of CSFV, it is likely that this will take many years, require changes to the

traditional management and husbandry practices adopted and need significant financial and

physical input to be successful.

136

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Appendix 1

Pig health and husbandry in West Timor

Farmer Questionnaire

Introduction to project: This questionnaire aims to improve our understanding of pig

management and the current situation on classical swine fever in NTT. The research is

being conducted by the Australian Centre for International Agricultural Research.

Interviewers are to read the instructions below and complete the following information.

Farmer Identification No: ______________

Please include:

* T for Timor, F for Flores, S for Sumba, L for Lembata

* Code for village 1-?

* Respondent No. (2 digits) 01-?

Example Code Identification No: T101 (T=Timor, 1=village 1, 01=respondent 1)

Name of Interviewer: ___________________________

Date of interview: ____/____/____ (dd/mm/yyyy)

Sub-district: ______________ Village: ______________

Name of farmer: __________________________

Instruction for interviewers:

1. Make sure that the person that you interview is the person who looks after the

pigs.

168

2. Explain to the farmer the purpose of the study and why we would like them to

answer the questions and take a blood sample from their pig using the following

words:

“You have been selected to participate in this questionnaire due to your

involvement with pigs in NTT. We would like you to answer a few questions as

this will help us to understand any problems farmers might have with their

animals as well as help us understand the management and health status of pigs

in NTT. Your involvement is voluntary and you are free to pass on any question

you do not want to answer or to stop the interview at any time. Everything you

do say will be confidential and used for project purposes only. The questionnaire

should take approximately 40 minutes. We are also collecting a blood sample as

we would like to see if we can find any disease. Once we have this information it

will allow us to understand the best way we can help farmers and their animals.”

The following information is only relevant to the interviewer (do not read out to

the farmer):

3. Complete the questionnaire with the farmer before blood samples are collected

from his/her pigs.

4. Read out the questions exactly as they are written in the questionnaire, this will

ensure consistency.

5. Some questions will not be asked of all farmers eg if no pigs were sick do not ask

how many were sick or what were the clinical signs

6. Tick the appropriate box or write answers in the space provided (some questions it

may be appropriate to tick more than one box or give more than one answer)

7. When recording answers for clinical signs of sick or dead pigs you must write

down exactly what is said and not your interpretation of what the farmer is telling

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you (for example using technical terminology such as lacrima, cachexia…which

the farmer would not use).

8. This questionnaire is a total of 10 pages. Please check before starting the

interview that all pages are present.

9. All hard copies of the questionnaire need to be retained following the interview.

Please report any errors in data entry here:

…………………………………………………………………………………………………………

PART A: Farmers’ Educational Background

A1. What is your educational background?

□ School not attended

□ Completed Primary School

□ Completed Junior High School

□ Completed Senior High School

□ Other_please specify_____________________________

A2. Have you ever attended any animal training?

□ Yes □ No

A3. If YES, what kind of training have you ever attended?

□ Animal rearing methods

□ Health and animal diseases

□ Animal feeding

□ Animal reproduction

□ Other_please specify_______________________

A4. Is raising pig your main occupation?

□ Yes □ No

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A5. If NO, what is your main occupation?

□ Civil servant/ Army/Police

□ Entrepreneur

□ Carpenter

□ Butcher

□ Restaurant owner

□ Other_ please specify_________________________

PART B: Farm Structure and Herd Information

B1. How many of the following animals do you have on your farm?

Cattle Buffalo Sheep Goats

FOR TETHERED OR PENNED PIGS - INTERVIEWER SHOULD CHECK

FARMER ANSWERS TO B2 AND B3 – WHEN LOOKING AT THE PIGS DURING

BLOOD COLLECTION

B2. How many pigs do you have of each sex and age group?

Write the number of pigs in herd on day of visit in each category. If no pigs in a

category write zero “0”.

Pig Age Total

Female Male Castrated Male

<3 months

3-6 months

>6-12m

>12m

Total

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B3. How many of your pigs are Local Breed? Cross Breed? Commercial Breed?

Definitions: Local / Native: Pigs that appear black in colour, curve back, ears

standing up, longer nose, can be smaller in size, belly-stomach is low to

the ground.

Cross Breed:Pigs that are characterised by straight back, shorten nose,

stomach is higher off the ground, and large ears.

Commercial pigs that are pure breed, raised for commercial purpose

only.

Write the number of pigs in herd on day of visit in each breed category.

Local / Native Cross Breed Commercial

B4. What is the system for raising pigs? (Interviewer to answer)

□ Traditional □Semi-intensive □ Intensive

Definitions: Traditional: system of raising pigs, where pigs often kept inside during

night and free range during the day. Approximately 1-10 pigs are present

in one household

Semi-intensive: pigs that are penned and possibly fed some commercial

food.

Intensive:characterised by a large number (>50) of pigs managed in

systems that include commercial feed, automatic water systems and

cleanable pens. Most of these farms also keep records of each animal and

use artificial insemination techniques.

B5. What is your purpose for keeping pigs? (Tick more than 1 box if necessary)

□Sold □ Traditional ceremonies

□Paying for school fees □For own consumption in the family

□For emergency needs □Other reason _________________

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B6. In raising pigs, what is the type of your pig raising?

□Fattening □ Breeding □Fattening and Breeding

PART C: Husbandry

C1. Housing and Biosecurity

C1.1. How is your pig kept? (Tick more than one box if necessary)

□In a pen □Tied up in home environment

□ Tied up under trees □ Free to roam

C1.2. (Interviewer to answer) If kept in a pen what is the condition of the pen?

Roof Wall Floor

All from zinc/roof-tile Fully brick ground

Half from zinc/ roof-tile Half brick rough cement

Without roof Without brick stones

All from leaves Wooden

wall/bamboo/filament

wood

Half from zinc/roof-tile Half from

wood/bamboo/filament

Staged floor from wood

or bamboo

C1.3. Do you clean the pig’s pens?

□ Yes □ No

C1.4. If YES, how often do you clean the pens?

□ Once daily □ Twice daily □ Once weekly

□ Twice weekly □ Once monthly □ Other_Please specify_________

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C1.5. What do you use to clean the pens?

□ Water □ Soaps (Detergent) □ Disinfectants (phenol, Lysol, creoline)

□ Other_please specify_______________

C1.6. Do you provide hand and feet-cleaning material at the exit and entrance door to

the pig pens?

□ Yes □ No

C1.7. If YES, what are the facilities do you provide?

□ Water □ Water and Soap □ Water with disinfectant (phenol, Lysol,

creoline)

□ Other_please specify_________________

C1.8. Do you require people to wear the following protective gear before entering the

pigs’ pens?

□ Not required □ Wearing boot □ Wearing boot and

wearpack

□ Wearing gloves □ Wearing mask □ Wearing boot and mask

C1.9. Do you limit vehicles entering your farm?

□ Yes □ No

C1.10. If Yes, please explain why do you limit the vehicles entering your farm?

______________________________________________________________________

C1.11. Do you treat vehicles when entering your farm?

□ Yes □ No

C1.12. Do you wash your pigs?

□ Yes □ No

C1.13. If YES, how often do you wash your pigs?

□ Once daily □ Twice daily (morning and afternoon)

□ Once weekly

□ Occasionally when needed □ Other_please specify____________

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C1.14. When do you look after your pigs during the day?

□ In the morning

□ At noon

□ In the afternoon

□ In the morning and afternoon

□ In the evening

C1.15. How long do you spend looking after your pigs?________ hours/ day.

C2. Feeding and Drinking Water

C2.1. Where do you get water from for your pigs?

□ Local stream/river □ Tap □ Well on property

□ Communal well □ Other – please specify________________

C2.2. How often do you feed your pigs?

□ Never- it finds own food □ Once daily □ Twice daily

□ Three times a day □ Other – please specify_______________

C2.3. What kind of feed do you give your pigs?

□ Swill from kitchen □ Swill from restaurants □ Manufactured feed

□ Own made feed □ Agricultural waste □ Other_please specify____

C2. 4. If you give swill to your pigs, do you cook the swill before you feed it to your

pigs?

□ Yes □ No

C2.5. How long do you cook the swill?

□ 15 minutes □ 30 minutes

□ Uncertain □ Other_please specify_______________

C2.6. Do you use an identification method with any of you pigs?

□ Yes □ No

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(i) If YES, please specify method used:

□ Tattoo □ Ear notch □ Ear tag

□ Spray paint □ Incision on ear(s) □ Other - please

specify ___

PART D: Reproductive Management and Performance

D1. How do you mate your pigs?

□ Artificial insemination □ Natural mating with own boar

□ Natural mating with borrowed boar □ Natural mating with free roaming

boar

D2. If you use natural mating, how did you do it?

□ Using boar from the same village

□ Using boar from village in the same subdistrict

□ Bring the sow to the boar in the same village

□ Bring the sow to the boar out of the village

D3. How many litters in the past 12 months? FOR EACH SOW – How many

piglets were born in total in the past 12 months? How many of these were

abnormal? How many were weaned?

(Complete the table on reproductive performance for each mated sows in the

herd over the last 12 months. (Instruction to Interviewer)

(If the respondent does not know, please write unknown in the appropriate cell).

Sow Partus: No. of

litters

Total No. of normal

piglets born

Total No. of piglets born

with abnormalities1

Total No. of piglets born then

died

Total No. of piglets weaned

1 1

2

3

2 1

2

3

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3 1

2

3

1Abnormalities can include congenital abnormalities, stillbirths or mummies

PART E: Pig Movement and Trading

E1. Have you introduced any pigs into your farm over the last 12 months?

□ Yes □ No

E2. If YES, how did you get the pigs?

□ Gift □ Bought □ From government

□ Tradition □ Other_please specify_____________________

E3. Where did you get the pigs?

□ Same village □ Village in the same subdistrict

E4. How many pigs did you purchase over the last 12 months? (Do not include pigs

received as gifts) FOR EACH PURCHASE – How many pigs did you buy?

What month was the purchase?, Why did you purchase these pigs?, Who did you

buy them from? Where did they come from?

No. Of pigs purchased

Month WHY? WHO? Where From?

Market □ Another farmer □ Pig seller not from market □ Other _________

District___________________ Subdistrict _______________ Village__________________

Market □ Another farmer □ Pig seller not from market □ Other _________

District___________________ Subdistrict _______________ Village__________________

Market □ Another farmer □ Pig seller not from market □ Other _________

District___________________ Subdistrict _______________ Village__________________

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Market □ Another farmer □ Pig seller not from market □ Other _________

District___________________ Subdistrict _______________ Village__________________

E5. When were you given pigs as a gift over the last 12 months?

FOR EACH GIFT - What was the celebration? eg wedding or funeral, What month

was the celebration? , How many pigs were given?, Was the pig(s) slaughtered on day

of you received it?, Did the pigs have contact with pigs already on your property?,

Where did the pigs come from?)

Celebration Month Pig no. Slaughter on receiving day

Contact with your pigs at home

Where From?

Yes No

Yes No Don’t know

District____________ Subdistrict ________ Village___________ Not sure □

Yes No

Yes No Don’t know

District____________ Subdistrict _________ Village____________ Not sure □

Yes No

Yes No Don’t know

District____________ Subdistrict _________ Village____________ Not sure □

Yes No

Yes No Don’t know

District____________ Subdistrict ________ Village____________ Not sure □

Yes No

Yes No Don’t know

District____________ Subdistrict _________ Village___ Not sure □

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E6. How many pigs left your herd during the last 12 months? (Please specify the

number of pigs that left your herd, the month they left, why they left, where they

went to and who received them)

No of pigs that left

Month WHY? Where did they go?

WHO received them?

□ Gift □ Ceremony □ Celebration □ Sold □ other

District_________ Subdistrict ______ Village________

Family/relative □ Farmer inside the village □ Farmer outside the village□ Sold at market □ Pig seller not from market □ Other ______________

□ Gift □ Ceremony □ Celebration □ Sold □ other

District_________ Subdistrict ______ Village_________

Family/relative □ Farmer inside the village □ Farmer outside the village□ Sold at market □ Pig seller not from market □ Other __________

□ Gift □ Ceremony □ Celebration □ Sold □ other

District_________ Subdistrict ______ Village_________

Family/relative □ Farmer inside the village □ Farmer outside the village□ Sold at market □ Pig seller not from market □ Other __________

□ Gift □ Ceremony □ Celebration □ Sold □ other

District_________ Subdistrict ______ Village_________

Family/relative □ Farmer inside the village □ Farmer outside the village□ Sold at market □ Pig seller not from market □ Other ___________

E7. How likely are you to sell pig for the following factors? (Please circle only one

answer for each question)

a. Need money

Very Unlikely Unlikely Not sure Likely Very Likely

b. Pig is sick

Very Unlikely Unlikely Not sure Likely Very Likely

c. Pig is getting old

Very Unlikely Unlikely Not sure Likely Very Likely

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E.8. What months are you most likely to sell your pig(s)? (Please circle all appropriate

months)

E.9 Please explain WHY you are more likely to sell pigs during these months:

________________________________________________

________________________________________________

E.10 What months are you less likely to sell your pig(s)? (Please circle all appropriate

months

E.11 Please explain WHY you are less likely to sell pigs during these months:

________________________________________________

________________________________________________

E12. When you sell your pigs how do you do it?

□ Seller comes and buy at home

□ I come to the market

□ Ask friend to sell it for me at the market

□ other____please specify___________

PART F: Health Status and Hog Cholera

F1. In the past 3 months have any of your pigs died suddenly without any signs of

illness?

Yes □ No □

i) If YES how many pigs have died suddenly? ______

F2. Apart from those that have died suddenly, have any of your pigs been sick or

died after showing signs of illness over the past 3 months?

Jan Jun Dec Feb Mar Apr May

Jul Aug Sept Oct Nov

Jan Jun Dec Feb Mar Apr May

Jul Aug Sept Oct Nov

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Yes □ No □

i) If YES please complete the following table.

FOR EACH SICK PIG – How old was the pig at the start of illness?, What sex? What

signs of illness?, Did you do anything to treat/help this sick pig? Did the pig die?, If pig

died, how many days from start of illness to death?

Pig No.

Age at start of illness (m)

Sex M/F

Clinical signs

What action was taken

Did the pig die? Y/N

Time between clinical signs and death (days)

1

2

3

4

5

Total sick Total died

F3. Generally, when you have a sick pig what do you do? (tick more than one option

if necessary)

□ Nothing

□ Tell the head of the village

□ Contact the Department of Agriculture (Dinas)

□ Use their own medicine (please specify)__________________

□ Use medicine from the Government (please specify)_______________

□ Use traditional medicine (please specify) ___________________

□ Other – please specify __________________

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F4. When a pig dies – What do you usually do with the body of the dead pig?

Please circle only one answer for each question

…If it was Sick Before

Death? Burn Bury Eat Other

(specify)_________________

…If it was a Sudden

Death? Burn Bury Eat Other

(specify)_________________

…If it was Healthy /

Not Very Sick Before

Death?

That is farmer

considered pig not to be

sick

Burn Bury Eat Other

(specify)_________________

F5. In the past 3 months have you heard of other people having pigs which are sick or

dead?

□ No □ Yes

i) If YES, please complete the following table

FOR EACH GROUP OF SICK PIGS YOU HEARD OF – Where were the pigs?,

How many sick pigs? What signs of illness? What disease if known? How many of

these sick pigs died?

Location No of pigs

sick

Clinical signs of

pigs

Disease (if

known)

No. of pigs

that died

Neighbours

Same village

Village in same

sub-district

Village in another

sub-district

F6. To your knowledge, do your pigs come in contact with any pigs that are not

owned by you at anytime?

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□ No □ Not sure □ Yes

(i) If YES, please tick the types of pigs that your pigs could come into contact

with:

� Wild pigs

� Your neighbour’s pigs

� Village pigs (pigs owned by other members of your village)

� Other Please specify ____________________________________

PART G: Farmer Perceptions and Vaccination

G1. Do you think the majority of your pig(s) are:

□ Skinny □ Not skinny and not fat □ Fat

G2. Have you heard about Hog Cholera?

□ No □ Yes

G3. If YES, where do you know it from?

□ Friends □ TV, Newspapers, radios

□ Field Agricultural worker □ Veterinarians/ paramedic vet.

□ Other___please specify

G4. Have you ever vaccinated your pig(s) for Hog Cholera?

□ No □ Yes- Please proceed to question G5

(i) If NO, could you tell us why you have not vaccinated your pigs?

□ It’s too dangerous

□ I don’t believe in vaccination

□ When the vaccinator came I wasn’t at home

□ Pig was too young

□ I use natural medicines instead

□ Other reason – please specify _________________________________

We have no further questions to ask. Thank you for your participation.

183

G5. Could you tell us why you vaccinate your pigs for Hog Cholera?

□ The veterinarians came and vaccinated the pigs

□ The animal health worker came and vaccinated the pigs

□ I wanted my pig to be healthy

□ I heard it was a good thing to do

□ Other animals in my village were vaccinated

□ Other– Please specify _____________________________________

G6. When was your current herd last vaccinated for Hog Cholera?

__/____/____dd/mm/yyyy

G7. How frequently are your pigs vaccinated for Hog Cholera?

□ Once only □ Yearly □ Whenever there is a campaign

□ Other – please specify _____________________________

Thank you for your participation

184

Appendix 2

SAMPLE DATA COLLECTION SHEET

District : ……………………. Sub-district : …………………...

Village : ……………………. RT/RW : ………………….

Sampling site : ……………………. Date : / / 2010

Pig ID Farmer’s Name Gender (M/CM/F)

Age (mm/yy)

Vaccinated against CSF?(Y/N)

Last vaccinated? (mm/yy)

Has it been sick

in the last 3

months?

How did you get this pig?

Body Condition Score (__/5)

Lab. result

In column ’how did you get this pig?’ type:

0: Do not know 1: Born in your herd In column ’age’ type: M=male, CM=castrated male, F=female

2: Purchased 3: Gift from family/relative

4: Distributed by the government/ local dinas