epidemiology of rabies in kenya

Philip M. Kitala1 and Stella Kiambi2

1University of NairobiDept Public Health, Pharm and Toxi

Email: [email protected] of Livestock Development

Zoonoses Disease Unit (ZDU)Email: [email protected]

Epidemiology of rabies in Kenya

mailto:[email protected]

History of rabies Rabies, an ancient disease, is well known in Kenya 1st confirmed rabies case was in 1912 in a dog in the

outskirts of Nairobi 1st documented human rabies case was in 1928 in a

woman from South Nyanza Records kept by the Vet Dept shows that Kenya

experienced rabies epidemics in early 1930s, late 1940s, and early 1950s

Epidemiology of rabies in Kenya

Widespread deployment of an egg-adapted life virus vaccine in the 1950s and 1960s, effectively controlled rabies so that by 1973, the disease was virtually eliminated from the country

However, following an outbreak in late 1974 in Taita/Taveta, the rabies situation changed dramatically

By 1979,the disease had spread along the densely populated coastal strip and along the Tanzania border to Trans Mara, South Nyanza, and Western Kenya

Epidemiology of rabies in Kenya…

By end of 1982, rabies had spread throughout Nyanza, Western Province, Central Rift Valley, Nairobi and adjacent areas

To date rabies is more widespread and prevalent in Kenya than at any time in its history

By 1992, only 4 districts of the then 41 (10%), had no confirmed rabies cases



Figure 1: Distribution of confirmed animal rabies cases in Kenya, 2002 – March, 2013


1958

1960

1962

1964

1966

1968

1970

1972

1974

1976

1978

1980

1982

1984

1986

1988

1990

1992

1994

1996

1998

2000

2002

2004

2006

2008

2010

2012

020406080

100120140160180200

Canine rabies cases in Kenya, 1958-2012

Year

Num

ber

of r

abie

s cas

es

Distribution of rabies cases by species The domestic dog remains the principal reservoir and

transmitter of rabies to both man and his other domestic animals in Kenya

From 1912 to end of May 1991, a total of 2931 animal specimens were confirmed positive with dogs accounting for 64.2% (1881)

Between 1983-1990, domestic dogs accounted for 63% of the 2149 animal rabies cases confirmed


By contrast, of the 1034 animal specimens confirmed positive for rabies in the last ten years (2002-March 2013), dogs accounted for 46% of the positives and cattle 37%.

We believe this apparent decline in dog rabies prevalence is a reflection of weaknesses of the surveillance of rabies in recent years – suspected rabies in the more economically important dairy cattle are more likely to be reported by their owners relative to suspected dog rabies cases.


Due to defective surveillance of rabies in the country these figures should only be taken as an indication of the rabies trend in the country and not a reflection of the true incidence of the disease and therefore rabies burden



Confirmed rabies cases by species in Kenya, 2002-March 2013


Central Eastern Nairobi N.Eastern Nyanza R.Valley Western0

50

100

150

200

250

The distribution of rabies cases by species and province of origin in Kenya during the period 2000 - 2010

No. Dogs No. Cattle No. Cats No goats No. Donkeys No. OthersProvince

Num

ber o

f rab

ies c

ases

Rabies trend in Kenya, 2002-March 2013


Role of wildlife in the epidemiology of rabies in Kenya remains unclear The disease has been confirmed in the following wildlife species:

Jackals Fox Mongoose (white-tailed) Hyena Genet cat Leopard Squirrel Monkey Honey badger Bat (Lagos bat virus, Shimoni bat virus)

The few wildlife rabies virus isolates so far typed have been found to be of

the canid type (Africa 1b) – indicating transmission from dogs to wildlife


Human cases of animal bites Over the last three years, a total of 318 456 cases of animal-bites were

documented countrywide: 2010 ---------------- 38 944 2011 ---------------- 133 150 2012 ---------------- 146 362

Assuming a human population of 40 million people, the crude estimate of animal-bite incidence for the three years:

2010 ---------------- 97 bites /100 000 population 2011 ----------------- 333 bites /100 000 population (3.4 times) 2013 ----------------- 366 bites /100 000 population (1.1 times)

Compare with incidence estimated for Machakos 1992/1993 of 234/100 000 population (97% by dogs) and for Tanzania in 2010 of 140/100 000 population


Human rabies cases Information on numbers of confirmed human rabies cases in

Kenya is scanty True incidence of human rabies deaths in Kenya is grossly

underestimated Reasons for this are many in Africa:1) Rabies victims are often too ill to travel to hospital or die

before arrival;2) Families recognize the futility of medical treatment for

rabies


3) Patients are considered to be the victims of bewitchment rather disease;

4) Clinically recognized cases at hospitals may go unreported to central authorities

5) Misdiagnosis is not uncommon


Spatial distribution of human rabies cases in Kenya, 2002-March 2013


Conclusions The rabies burden in Kenya is likely to be substantial

but its size and extent remains unknown The domestic dog remains the principal reservoir and

vector of rabies in the country Past rabies control efforts have been ineffective Rabies occurs over large parts of the country mainly

due to a large, poorly supervised, and inadequately protected dog population by vaccination


What is lacking? Better reporting of both rabies cases and dog bites in the

country Better communication between the veterinary and

medical communities in terms of: Outbreak reporting Information flow Joint vaccination programs Budgets


Scaled-up approach across wide regions rather than a one-off exercise

• Big scale interventions over long periods of time, with annual vaccination of dogs• Centralized management Commitment to a sustained budget

CAN IT BE DONE?



1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 20040

2

4

6

8

10

12

14

16

18

0

10

20

30

40

50

60

70

7.1 7.5

9.1 9.3 9.710.6 10.9 11.1

12.613.3 13.7

14.915.9 16.2

14.560

45

29

2019

22

15

20

73 0 1 0

1 0

Cases of rabies in humans

Vaccinated dogs(Millions)

THANK YOU!


epidemiology of rabies in kenya

Documents