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Foodborne disease surveillance and outbreak investigations in Western Australia, fourth quarter 2014

OzFoodNet, Communicable Disease Control Directorate

Enhancing foodborne disease surveillance across AustraliaCommunicable Disease Control Directorate

Acknowledgments

Acknowledgement is given to the following people for their assistance with the activities

described in this report: Mr Damien Bradford, Ms Lyn O’Reilly, Ms Jenny Green, Mr Ray

Mogyorosy and the staff from the enteric, PCR and food laboratories at PathWest

Laboratory Medicine WA; Mrs Anna Anagno and other staff from the Food Unit of the

Department of Health, Western Australia; Public Health Nurses from the metropolitan and

regional Population Health Units; and Local Government Environmental Health Officers.

Contributors/Editors

Barry Combs and Nevada Pingault

Communicable Disease Control DirectorateDepartment of Health, Western AustraliaPO Box 8172Perth Business CentreWestern Australia 6849

Email: [email protected]

Telephone: (08) 9388 4999

Facsimile: (08) 9388 4877

Web: OzFoodNet WA Health www.public.health.wa.gov.au/3/605/2/ozfoodnet_enteric_infections_reports.pmOzFoodNet Department of Health and Ageingwww.ozfoodnet.gov.au/

Disclaimer:

Every endeavour has been made to ensure that the information provided in this document

was accurate at the time of writing. However, infectious disease notification data are

continuously updated and subject to change.

This publication has been produced by the Department of Health, Western Australia.

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http://www.ozfoodnet.gov.au/

http://www.public.health.wa.gov.au/3/605/2/ozfoodnet_enteric_infections_reports.pm

mailto:[email protected]

Executive summary During the fourth quarter 2014, the Western Australian (WA) OzFoodNet team conducted

surveillance of enteric diseases and investigated outbreaks.

The most common notifiable enteric infections in WA were campylobacteriosis (n=883),

salmonellosis (n=301), rotavirus (n=129) and cryptosporidiosis (n=70). Notifications of

campylobacteriosis, cryptosporidiosis and rotavirus were higher than the 5 year fourth

quarter mean, while salmonellosis notifications decreased compared to the 5 year fourth

quarter mean.

Investigations were conducted into four foodborne outbreaks, one due to Salmonella

Typhimurium associated with a restaurant, one suspected toxin mediated outbreak

associated with a bowling club, a norovirus outbreak associated with a graduation dinner

and a norovirus outbreak associated with a dormitory campsite. The investigation into the

increase in S. Typhimurium PFGE 0001 cases continued in the fourth quarter.

OzFoodNet also conducted surveillance of 53 non-foodborne outbreaks. Of these, the

most common mode of transmission was person-to-person (47 outbreaks), with a total of

1287 people ill. Norovirus was the main agent responsible for infection (28 outbreaks), and

most of the person-to-person outbreaks were in residential care facilities. There were five

outbreaks with an unknown mode of transmission, with a total of 50 people ill. There was

one suspected waterborne outbreak associated with a swimming pool.

Figure 1 Notifications of the four most common enteric diseases by quarter from 2009 to 2014, WA

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Table of Contents

Executive summary...........................................................................................................21 Introduction.................................................................................................................52 Incidence of notifiable enteric infections.................................................................6

2.1 Methods..................................................................................................................62.2 Campylobacteriosis.................................................................................................62.3 Salmonellosis..........................................................................................................72.4 Rotavirus infection...................................................................................................82.5 Cryptosporidiosis.....................................................................................................92.6 Other enteric diseases and foodborne illness.......................................................10

3 Foodborne and suspected foodborne disease outbreaks....................................113.1 Restaurant outbreak: Salmonella Typhimurium PFGE 0001 ...............................113.2 Bowling Club outbreak: aetiology unknown .........................................................113.3 Graduation dinner outbreak: norovirus .................................................................123.4 Camp outbreak: norovirus ....................................................................................12

4. Cluster investigations...............................................................................................124.1. S. Typhimurium PFGE 0001, phage type 9...........................................................124.2. S. Typhimurium PFGE 0039, phage type 135a.....................................................13

5. Non-foodborne disease outbreaks and outbreaks with an unknown mode of transmission.....................................................................................................................13

5.1. Person-to-person outbreaks..................................................................................145.2. Outbreaks with unknown mode of transmission....................................................155.3. Suspected waterbourne outbreak.........................................................................16

6. Site activities.............................................................................................................167. References.................................................................................................................17

List of Tables

Table 1 Number of campylobacteriosis notifications, 4th quarter 2014, WA, by region...................7Table 2 Number of salmonellosis notifications, 4th quarter 2014, WA, by region...........................7Table 3 Number of rotavirus notifications, 4th quarter 2014, WA, by region.................................9Table 4 Number of cryptosporidiosis notifications, 4th quarter 2014, WA, by region...................10Table 5 Outbreaks with non-foodborne transmission, 4th Quarter 2014, WA..............................14

List of Figures Figure 1 Notification rates of the four most common enteric diseases by quarter from 2009 to 2014, WA....................................................................................................................................... 2

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Notes:

1. All data in this report are provisional and subject to future revision.

2. To help place the data in this report in perspective, comparisons with other reporting periods are provided. As no formal statistical testing has been conducted, some caution should be taken with interpretation.

Copyright to this material is vested in the State of Western Australia unless otherwise indicated. Apart from any fair dealing for the purposes of private study, research, criticism or review, as permitted under the provisions of the Copyright Act 1968, no part may be reproduced or re-used for any purposes whatsoever without written permission of the State of Western Australia.

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1 IntroductionIt has been estimated that there are 5.4 million cases of foodborne illness in Australia

each year at a cost of $1.2 billion per year1. This is likely to be an underestimate of the

total burden of gastrointestinal illness as not all enteric infections are caused by foodborne

transmission. Other important modes of transmission include person-to-person, animal-to-

person and waterborne transmission. Importantly, most of these infections are preventable

through interventions at the level of primary production, commercial food handling,

households and institution infection control.

This report describes enteric disease surveillance and investigations carried out during the

fourth quarter of 2014 by OzFoodNet WA, other WA Department of Health (WA Health)

agencies and local governments. Most of the data are derived from reports to WA Health

of 16 notifiable enteric diseases by doctors and laboratories. In addition, outbreaks caused

by non-notifiable enteric infections are also documented in this report, including norovirus,

which causes a large burden of illness in residential care facilities (RCF) and the general

community.

OzFoodNet WA is part of the Communicable Disease Control Directorate (CDCD) within

WA Health, and is also part of the National OzFoodNet network funded by the

Commonwealth Department of Health2. The mission of OzFoodNet is to enhance

surveillance of foodborne illness, including investigating and determining the cause of

outbreaks. OzFoodNet also conducts applied research into associated risk factors and

develops policies and guidelines related to enteric disease surveillance, investigation and

control. The OzFoodNet site, based in Perth, is responsible for enteric disease

surveillance and investigation in WA.

OzFoodNet WA regularly liaises with staff from Public Health Units (PHUs), the Food Unit

in the Environmental Health Directorate of WA Health; and the Food Hygiene, Diagnostic

and Molecular Epidemiology laboratories at PathWest Laboratory Medicine WA.

PHUs are responsible for public health activities, including communicable disease control,

within their respective administrative regions. The PHUs monitor RCF gastroenteritis

outbreaks and provide infection control advice. The PHUs also conduct follow up of single

cases of important enteric diseases including typhoid, paratyphoid and hepatitis A.

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The Food Unit liaises with Local Government (LG) Environmental Health Officers (EHO)

during the investigation of food businesses. The Food Hygiene, Diagnostic and Molecular

Epidemiology laboratories at PathWest Laboratory Medicine WA provide public health

laboratory services for the surveillance and investigation of enteric disease.

2 Incidence of notifiable enteric infections2.1 Methods

Enteric disease notifications were extracted from the Western Australian Notifiable

Infectious Diseases Database (WANIDD) by optimal date of onset (ODOO) for the time

period 1st October 2009 to 31st December 2014. The ODOO is a composite of the ‘true’

date of onset provided by the notifying doctor or obtained during case follow-up, the date

of specimen collection for laboratory notified cases, and when neither of these dates is

available, the date of notification by the doctor or laboratory, or the date of receipt of

notification, whichever is earliest. Rates were calculated using estimated resident

population data for WA from Rates Calculator version 9.5.5 (WA Health, Government of

Western Australia), which is based on 2011 census data. Rates calculated for this report

have not been adjusted for age.

2.2 Campylobacteriosis

Campylobacteriosis was the most commonly notified enteric disease in WA in the fourth

quarter of 2014 (4Q14), with 883 notifications (Table 1) and a 41% increase in notifications

compared to the five year mean of fourth quarter notifications (4QM). The WA 4Q14 rate

was 140 per 100 000 population per year compared to the 4QM rate of 107 per 100 000

population per year. The increase appeared to be due to sporadic disease, as there were

no identified campylobacteriosis outbreaks during the 4Q14. The increase is, in part,

thought to be due to the introduction of polymerase chain reaction (PCR) testing of faecal

specimens by one pathology laboratory, which has greater sensitivity than culture

techniques. Of the nine public health regions, six had an increase of more than 32% in

campylobacteriosis notifications compared to the five year mean of fourth quarter

notifications (Table 1).

The place of acquisition of infection was reported for 59% (n=521) of cases, of which 79%

(411 cases) were locally acquired and 19% (101 cases) were acquired overseas.

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Table 1 Number of campylobacteriosis notifications, 4th quarter 2014, WA, by region

Region 2014 4th Quarter 5 Year Mean for 4th Quarter

4th Quarter % change*

North Metro 346 261 32South Metro 330 215 54South West 86 53 63Midwest 25 15 62Wheatbelt 24 23 3Great Southern 21 23 -9Pilbara 18 10 76Goldfields 16 17 -4Kimberley 15 8 92WA address not specified 2 3 -37Total 883 628 41© WA Department of Health 2014

Number of notifications

*Percentage change in the number of notifications in the current quarter compared to the historical five-year mean for the same quarter. Positive values indicate an increase when compared to the historical five-year mean of the same quarter. Negative values indicate a decrease when compared to the historical five-year mean of the same quarter.

2.3 Salmonellosis

Salmonellosis was the second most commonly notified enteric disease in WA in the 4Q14,

with 301 notifications (Table 2) and a 3% decrease in notifications compared to the 4QM

notifications. The WA 4Q14 rate was 47 per 100 000 population per year compared to the

4QM rate of 53 per 100 000 population per year.

Table 2 Number of salmonellosis notifications, 4th quarter 2014, WA, by region

Region 2014 4th Quarter

5 Year Mean for 4th Quarter


North Metro 108 126 -14South Metro 104 99 5Kimberley 29 19 56South West 24 22 11Pilbara 12 9 28Goldfields 7 7 0Wheatbelt 7 10 -31Midwest 6 10 -37Great Southern 3 8 -62WA address not specified 1 4 -75Total 301 310 -3© WA Department of Health 2014



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Place of acquisition of infection was known for 75% (n=226) of cases, of which 58% (131

cases) were locally acquired, 40% were acquired overseas (90 cases) and 2% were

acquired interstate (5 cases).

The most commonly reported Salmonella serotype was S. Typhimurium (STM) (n=95),

and of those cases with information on place of acquisition (n=70, 74%), 59 cases (84%)

were locally acquired. Pulsed-field gel electrophoresis (PFGE) is used in WA for the

subtyping of STM and the most common PFGE types were type 0001 (n=26) and type

0039 (n=21). Cases with type 0001 were interviewed as part of an on-going cluster

investigation (see section 4).

S. Enteritidis was the second most common Salmonella serotype (n=44), and place of

acquisition was known for all cases and most (n=42, 95%) acquired their infection

overseas, primarily after travel to Indonesia (n=27, 61%).

The next most commonly notified Salmonella serotypes were S. Paratyphi B var Java,

(n=13), S. Virchow, (n=12) and S. Stanley (n=10).

2.4 Rotavirus infection

Rotavirus infection was the third most commonly notified enteric disease in WA in the

4Q14, with 129 notifications (Table 3) and a 61% increase in notifications compared to the

4QM notifications. The WA 4Q14 rate was 20 per 100 000 population per year compared

to the 4QM rate of 13 per 100 000 population per year.

This increase can, in part, be explained by an outbreak of rotavirus in a single residential

care facility in the South Metropolitan area with 15 cases positive for rotavirus.

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Table 3 Number of rotavirus notifications, 4th quarter 2014, WA, by region




South Metro 50 24 108North Metro 42 35 20Goldfields 12 5 167Kimberley 8 1 700South West 8 8 0Pilbara 4 5 -20Midwest 2 2 0Wheatbelt 2 1 300Great Southern 1 1 0Total 129 80 61© WA Department of Health 2014


*Percentage change in the number of notifications in the current quarter compared to the historical two-year mean for the same quarter. Positive values indicate an increase when compared to the historical two-year mean of the same quarter. Negative values indicate a decrease when compared to the historical two-year mean of the same quarter. Only two years (2012-2013) of data was used for the historical mean as changes in laboratory testing practice (increased use of more specific PCR over antigen testing) over the period 2009 to 2011 complicate comparison to 5-year data.

2.5 Cryptosporidiosis

Cryptosporidiosis was the fourth most commonly notified enteric disease in WA in the

4Q14, with 70 notifications (Table 4) and a 52% increase in notifications compared to the

4QM notifications. The WA 4Q14 rate was 11 per 100 000 population per year compared

to the 4QM rate of 8 per 100 000 population per year. The increase in notifications was

mainly observed in the Pilbara region where there was an outbreak associated with a

swimming pool. The increase in part, may be due to the introduction of PCR testing of

faecal specimens by one pathology laboratory, which has greater sensitivity than

microscopy and enzyme immunoassay techniques. The place of acquisition of infection

was reported for 83% of cases (n=58) of which 88% (51 cases) were locally acquired and

12% were overseas acquired (7 cases).

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Table 4 Number of cryptosporidiosis notifications, 4th quarter 2014, WA, by region




South Metro 20 14 47Pilbara 14 2 483Kimberley 12 11 13North Metro 12 9 33South West 4 5 -20Great Southern 3 1 114Midwest 2 1 150Goldfields 1 2 -50Wheatbelt 1 1 25WA address not specified 1 1 67Total 70 46 52© WA Department of Health 2014



2.6 Other enteric diseases and foodborne illness

During the 4Q14, other enteric disease notifications included:

Shigella infection: There were 33 Shigella notifications in 4Q14 that were culture

positive, which was 80% higher than the five year mean (n=18). Aboriginality status

was known for all cases and 39% (n=13) were Aboriginal people and 61% (n=20)

were non-Aboriginal people. The increase in notifications was partly due to an

outbreak in an Aboriginal community. Of the non-Aboriginal people, 10 (50%) had

travelled overseas. For the 4Q14, Shigella species included S. sonnei (n=27), S.

flexneri (n=5) and S. boydii (n=1).

Hepatitis A infection: Four hepatitis A cases aged 5 to 34 years were notified in

the 4Q14 and all were overseas acquired. Two cases had travelled to India, one

had travelled to Somalia and one had travelled to the Philippines.

Typhoid fever: Four cases of typhoid fever were notified in 4Q14. All were male

(aged 2-31 years) and acquired their infection in India (n=2), Sri Lanka (n=1) and

Indonesia (n=1).

Vibrio parahaemolyticus infection: Three locally acquired cases (all male, 37-69

years) and four overseas acquired (one male and three females, aged 9-58 years)

cases were notified in 4Q14. The overseas acquired cases reported travel to

Indonesia (n=2), Thailand (n=1) and Vietnam (n=1).

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Listeria monocytogenes infection: Two cases, both male aged 59 and 91 years

were notified in 4Q14. One case did not report any high risk foods and the second

case reported eating ham and salami. The MLVA types of the two cases were

different to each other and the other three cases notified in 2014.

Yersinia infection: There were two Yersinia notifications in 4Q14 that were culture

positive (one male aged 83 and one female aged 61 years). Both isolates were

identified as Y. enterocolitica.

Paratyphoid fever : Two cases (both male, aged 21 and 29 years) of S. Paratyphi

A were notified in 4Q14 and acquired their infection in India and Burma.

There were no notifications for STEC, botulism, cholera, or hepatitis E in this

quarter.

3 Foodborne and suspected foodborne disease outbreaks

There were four foodborne disease outbreak investigated in this quarter.

3.1 Restaurant outbreak: Salmonella Typhimurium PFGE 0001 (outbreak code 042-2014-010)

Four people independently ate food at a metropolitan restaurant from 19/09/2015 to

25/09/2015 and subsequently became ill with STM PFGE 0001. There were three male

cases and one female with a median age of 34 years (range 30-45 years). The median

incubation period was 2.4 days (range 2.3 to 4.6 days), with median diarrhoea duration of

8.5 days and one case was hospitalised. Three cases reported eating a slow roasted pork

hock meal and the fourth case could not recall food eaten. The local government

environmental health officer investigated the food business and found no evidence of

possible cross-contamination or inadequate food handling.

3.2 Bowling Club outbreak: unknown (outbreak code 12/14/TWD)Following a function at a bowling club in December 2014, there were reports of

gastroenteritis among the 60 attendees. Of the 19 attendees interviewed, 13 reported

illness. Symptoms reported included diarrhoea (100%), abdominal pain (92%) and

vomiting (8%) with a median incubation period of 12 hours and median duration of

diarrhoea of 11 hours. No faecal specimens were tested, but illness characteristics

suggest Clostridium perfringens food poisoning. Food was prepared by a caterer and

included roast meats salads and several desserts. An analytical study found a statistical

association between eating roast meats and becoming ill. Local government conducted the

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environmental health investigation of the food business and at the time of the investigation,

the food business could not provide evidence of safe food handling, processing and

hygiene.

3.3 Graduation dinner outbreak: norovirus (outbreak code 12/14/NOR)There was a report of gastroenteritis among 48 people who attended a graduation dinner

at a restaurant in December 2014. Information was obtained from 40 of the attendees and

21 people had diarrhoea and/or vomiting. The median incubation period was 36 hours

(range 12-53 hours) and median duration of illness was 2 days (range 1-5 days). One

person was tested and was positive for norovirus. Food was served as a buffet and

including hot pasta dishes, salads, roast potatoes and roast beef, and several desserts.

Consumption of salads was statistically associated with illness. There were no reports of

staff illness prior to the meal. The evidence suggests the outbreak was due to salad(s)

contaminated with norovirus but the source of the norovirus was unknown.

3.4 Camp outbreak: Norovirus (outbreak code 12/14/WOO)An investigation was conducted into a gastroenteritis outbreak associated with people

attending a dormitory campsite from 19th December to the 30th December 2014.

Information was obtained from 42 attendees and at least 30 (71%) people became ill with

diarrhoea and/or vomiting. The median duration of illness was 2 days (range 0.08-5 days).

One faecal specimen was positive for norovirus. Main meals were prepared by catering

staff and morning and afternoon teas were prepared by campers and volunteers. An

analytical study found associations between illness and eating multiple foods on 28/12/14.

No campers or staff reported illness prior to the outbreak at the camp. The environmental

health investigation identified only minor cleaning issues. Based on the evidence, the

outbreak was due to suspected foodborne transmission but it was not possible to clearly

identify the source of the norovirus contamination.

4. Cluster investigationsThere were two cluster investigations during the fourth quarter of 2014.

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4.1. S. Typhimurium PFGE 0001, phage type 9

There were 29 cases of PFGE type 0001 notified with illness, with specimen dates

between 1/10/14 and 30/12/14. The cases included 52% males and 48% females, ranged

in age from <1 to 89 years (average 25 years), and most (72%) resided in the Perth

metropolitan area. Chicken meat sampled in September and October 2014 was also

positive for PFGE type 0001. Of the 29 cases, 18 were interviewed leading to the

hypothesis that the consumption of free range eggs or chicken meat was the cause of

illness. Investigation is ongoing.

4.2. S. Typhimurium PFGE 0039, phage type 135a

There were 12 cases of S. Typhimurium PFGE type 0039 with specimen dates between

15/10/14 and 18/11/14. The cases comprised 9 males and 3 females, with ages ranging

from <1-52 years. Five of the cases were fly-in fly-out workers at mine sites in the Pilbara

region, with 2 cases at same mining camp. The mining camps were operated by different

companies, with different catering companies. Two cases were in Queensland for their

incubation period. All cases reported eating eggs in the incubation period. Eleven samples

were referred to Queensland for MLVA typing. Seven isolates had the MLVA profile 03-12-

12-09-523, which was the dominant MLVA profile seen in Queensland during 2014 and

linked to egg outbreaks. The source of the Salmonella illness could not be established.

5. Non-foodborne disease outbreaks and outbreaks with an unknown mode of transmission

There were 53 outbreaks of enteric disease in this quarter that appeared to be non-foodborne (see Table 5). Of these, 47 outbreaks were ascribed to person-to-person transmission, five had an unknown mode of transmission and one was suspected waterborne transmission.

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Table 5 Outbreaks with non-foodborne transmission, 4th Quarter 2014, WA

Mode of transmission

Setting Exposed

Agent responsible Number of outbreaks

Number of cases

Number hospitalis

ed

1 Number died

Person to person Aged care Norovirus 23 941 22 6Aged care Rotavirus 1 19 0 0Aged care Unknown 5 84 2 0

Aged care total 29 1044 24 6

child care Norovirus 2 31 1 0Unknown 9 109 4 0

Campylobacter species

1 9 0 0

child care total 12 149 5 0

hospital Norovirus 2 38 0 0

Unknown 1 8 0 0hospital Total 3 46 0 0community Shigella sonnei

biotype a1 23 7 0

institution Unknown 1 20 0 0

Ship Norovirus 1 5 1 0Total 47 1287 37 6Unknown aged care Unknown 4 34 1 1

function Norovirus 1 16 0 0Total 5 50 1 0suspected waterborne Swimming pool Cryptosporidium 1 6 0 0Grand total 53 1343 38 7© WA Department of Health 2014

Outbreaks with non-foodborne transmission

1 Deaths temporally associated with gastroenteritis, but contribution to death not specified

5.1. Person-to-person outbreaks

In the 47 non-foodborne outbreaks that were suspected to be due to person-to-person transmission, 29 outbreaks (62%) occurred in RCFs, 12 were in child care centres (26%), three were in hospitals (6%), and one each occurred in an institution, an Aboriginal community and on a ship. The causative agent for 28 (60%) outbreaks was confirmed as norovirus and one outbreak each was caused by Campylobacter, Shigella sonnei biotype a and rotavirus. The remaining 16 (34 %) outbreaks had unknown aetiology, as specimens were either not collected (n=10), were negative for common viral and bacterial pathogens (n=4), or viral tests were not requested (n=1). The aetiology was unknown for one

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childcare outbreak as one specimen was negative for common viral and bacterial pathogens and one specimen was positive for Salmonella but illness characteristics of the outbreak were not typical of Salmonella.

A total of 1287 people were affected in these 47 outbreaks, with 37 hospitalisations and six associated deaths. The number of person-to-person outbreaks in the 4Q14 was 62% higher than the fourth quarter mean (n=29).

Two significant person-to-person outbreaks are described below.

Childcare: Campylobacter (outbreak code 11-2014-001)Eight children (mainly in nursery room) were ill with gastroenteritis at a childcare centre

with onsets from 11/09/2014 to the 29/09/2014 and one staff with illness onset 8/10/2014.

Four children were positive for Campylobacter. Two mothers were also positive for

Campylobacter and had onsets 18/09/2014 and 7/10/2014. The median duration of

diarrhoea was 4 days (range 2-11 days). The children had not had contact with petting zoo

animals, cats or dogs, but did have contact with a rabbit and guinea pig. As the dates of

illness onset were over a long period of time, person-to-person transmission was suspected.

Aboriginal community: Shigella (outbreak code 008-2014-001)There was a report of gastroenteritis in an Aboriginal community with 23 ill people and

onsets from 13/10/2014 to the 8/11/2014. The average age was 2.5 years old (range <1 to

30 years). Of the 23 cases, 7 (30%) were hospitalised. Four people were positive for

Shigella sonnei biotype a. Two of these Shigella cases had a co-infection with Salmonella

and another case had a co-infection with rotavirus. The outbreak started after the

community hosted a sporting event in early October when the community population more

than tripled. As the dates of illness onset were over a long period of time, person-to-person

transmission was suspected.

5.2. Outbreaks with unknown mode of transmissionThere were five outbreaks in this quarter with an undetermined mode of transmission. Four

of these outbreaks were in RCFs and the time period of illness onsets ranged from two to

five days. Illness characteristics were not norovirus-like as all cases had diarrhoea and a

low percentage of cases vomited. Specimens from two RCF outbreaks were negative for

common viral and bacterial pathogens. Specimens from the other two RCF outbreaks

were negative for common viral and bacterial pathogens including C. perfringens and

Bacillus cereus. The fifth outbreak due to norovirus and was associated with a function

centre and is described below. A total of 50 people were affected in the five outbreaks,

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with one reported hospitalisation and no deaths. The number of unknown outbreaks in the

4Q14 was similar to the fourth quarter mean (n=4.5).

Function centre outbreak: aetiology unknown (outbreak code 12/14/GDC)

In December 2014, 77 elderly people with physical and/or mental impairment plus 16

staff/volunteers attended a function. Following reports of gastroenteritis among attendees,

12 staff and 18 clients were interviewed, and 16 (53%) reported illness including diarrhoea

(100%), vomiting (63%) and fever (31%). The median incubation period was 18 hours

(range 7-48 hours) and average duration of illness was 2.3 days. Two faecal specimens

were positive for norovirus. Two of the ill clients were residents at an RCF where a

subsequent norovirus outbreak occurred. The Christmas meal at the function was

prepared by caterers and all attendees were served the same food. No analytical study

was conducted. An entertainer at the function was ill with gastroenteritis at the time of the

function but did not report any interaction with clients. The conclusion was that the

outbreak was due to be norovirus, but the mode of transmission was unknown.

5.3. Suspected waterbourne outbreakSwimming pool: Cryptosporidium (outbreak code 081-2014-003)There were six cases of Cryptosporidium notified who resided in the same rural town with

onsets from 1/11/2014 to the 21/11/2014. There were two males and four females with a

median age of 7 years (range 1 to 40 years). The median duration of diarrhoea was 12

days (range 4-14 days). All the cases had visited the same swimming pool during their

incubation period. Pool management super chlorinated the pool to inactivate any

Cryptosporidium.

6. Site activitiesDuring the fourth quarter of 2014, the following activities were conducted at the WA OzFoodNet site:

Ongoing surveillance of foodborne disease in WA.

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Monitoring culture-independent nucleic acid amplification diagnostic testing in private laboratories and impact on notification rates.

Investigation of four foodborne outbreaks. Investigation and monitoring of 47 suspected person-to-person outbreaks, five

outbreaks with unknown mode of transmission and one suspected waterborne outbreak.

Two clusters of Salmonella infection were investigated. Sent out an alert to residential care and childcare facilities regarding increased

norovirus infections. Responded to national OzFoodNet enteric disease surveillance requests. Attendance at the OzFoodNet face-to-face meeting in Brisbane in December. Attended meeting with CDCD staff, the FoodUnit, and Department of Agriculture

and Food to discuss zoonotic diseases in WA. Co-author on presentation “Investigation of a diarrhoea only outbreak in a

residential care facility” for the WA Public Health Nurses Update Meeting, in November.

In November, presented at Environmental Health Officers workshop on foodborne outbreak investigations.

Performed data analysis on egg related outbreaks as part of national working group.

Contributed to a discussion paper presented to CDNA on enteric pathogen surveillance needs.

Interviewing Salmonella Enteritidis cases regarding travel status and attempting to identify risk factors in locally acquired cases.

Ongoing meetings with the WA Health Food Unit to improve coordination of foodborne disease surveillance and investigation in WA.

Continuing to work with PathWest on the introduction in WA of MLVA typing of S. Typhimurium isolates and PCR testing of bloody stools for STEC.

Membership of OzFoodNet working groups on:o National STEC surveillance.o Outbreak register.o Foodborne disease tool kito Culture independent testing

Membership of national working groups on the: o Review of the Series of National Guidelines for Hepatitis A. o Rotavirus Surveillance.

Chair of the Series of National Guidelines committee for ListeriaParticipation in monthly national OzFoodNet teleconferences.

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7. References1 Hall G, Kirk MD, Becker N, Gregory JE, Unicomb L, Millard G, et al. Estimating

foodborne gastroenteritis, Australia. Emerg Infect Dis 2005;11(8):1257-1264.2 OzFoodNet Working Group. A health network to enhance the surveillance of

foodborne diseases in Australia. Department of Health and Ageing 2013. www.ozfoodnet.gov.au/internet/ozfoodnet/publishing.nsf/Content/Home-1 [14/03/2012].

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