Epidemiology of Brucellosis in Cattle and Its Sero Prevalence in Animal Health Professionals in Sidama Zone, Southern Ethiopia
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Date
2004
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Abstract
Brucellosis is a widespread infectious disease of livestock and wild life with serious economic and public health impact. Bovine brucellosis causes diminution of much needed human food (milk and meat). Besides, being transmitted to man, it is one of the most important causes of abortion, stillbirth and infertility in cattle. The objectives of this study were, to investigate the current epidemiological picture of brucellosis in cattle in intensive and extensive management systems, identify and describe some of the associated intrinsic and extrinsic risk factors and to see the zoonotic importance of the disease.
The study was conducted from September 2003 to April 2004, in Sidama Zone (Southern Nations Nationalities Peoples Regional state). In the study area, six out of ten Woredas were considered for the investigation. Breeding cattle (n=2438) above six months of age were drawn in from both management systems with no history of vaccination. To this effect, a total of 811 Frisian and their crosses from intensive and 1627 indigenous zebu from extensive management system were considered. Furthermore 38 individuals thought to be at risk due to their occupational nature, with particular emphasis given to Veterinarians, Animal health Assistants, Animal Health Technicians, Artificial Insemination Technicians and Meat Inspectors were made part of the study.
Serum samples collected from both animals and humans were screened using Rose Bengal Plate Test (RBPT). Positive reactors were further subjected to Complement Fixation Test to maximize specifity and positive predictive value.
In this study, an over all prevalence of 2.46% in intensive and 1.66% in extensive management systems has been established. Among the risk factors investigated (Age, sex, herd size and management), only age was found to be associated with the infection (P<0.05).
Of the total herds investigated, 9.22 % (n=347) of them were confirmed to consist at least one infected animal. The herd level infection rates were 6.72 % (n=223) and 13.70 % (n=124) for intensive and extensive management, respectively. Infected herds have been detected from all Woredas except Arroresa. Accordingly, the rate of seroreactor herds observed were, 33.3% (n=6) for Awassa, 15.38 % (n=26) for Yirgalem, 13.15 % (n=38) for Aletawendo, 14.29 % (n=14) for Hagereselam and 18.18 % (n=22) for Arbegona in extensive management. In the
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intensive counter part 8% (n=125) for Yirgalem and 5.1% (n=98) for Awassa have been established.
As the observed average herd size was different for either of the management systems, categorizations into small, medium and large herds was done differently. Consequently, in intensive management system, 2.87%, 9.58% and 33.36% were the infection rate for small, medium and large herds, respectively. In the extensive system the result was, 4.81% for small, 50% for medium and 70% for large herds. In both intensive and extensive management systems, the variation between small and large was statistically significant (P<0.01).
In intensive urban and periurban dairy, 17.48% of the herds reported at least one of the reproductive disorders (abortion, still birth and fetal membrane retention with or with out any of the disorders).
5.3% of the occupationally risked individuals’ sera produced evidence of infection. In the situation where individual animal level infection rate was fond to be low, detection of reactors with this magnitude shows brucellosis being an occupational hazard.
In general the study concluded that, brucellosis is prevalent at low (individual), relatively high (herd) and wide (Geographical) distribution. The infection has involved both management systems (intensive and extensive) and occupationally exposed individuals. The disease among professionally exposed groups needs further validation by including more numbers.
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Brucellosis, RBPT, CFT, Zoonoses