Seroprevalence and risk factors for brucellosis in small ruminant flocks in Karnataka in the Southern Province of India

Abstract

Background and Aim: Brucellosis is a zoonotic disease of high economic and public health importance in large and small ruminant populations worldwide. A cross-sectional study was conducted to determine the seroprevalence and risk factors of brucellosis in small ruminants in organized farms in the southern region of India. Materials and Methods: Farms exclusively rearing sheep and goats were selected based on the number of animals (small, medium, or large) and the location of the farm (urban, periurban, or rural). A total of 1499 serum samples; 1001 from sheeps and 498 from goats were sourced from six sheep and four goat farms and tested using Rose Bengal Plate and indirect Enzyme-Linked Immunosorbent Assay tests. Results: The apparent prevalence of brucellosis was higher in sheep (8.29%, 95% CI 6.7-10.1) than goats (5.82%, 95% CI 4.0-8.2). The true adjusted population level seroprevalence was also higher in sheep, at 7.7% (95% CI 6.0-9.6) than in goats, at 5.1% (95% CI 3.2-7.6). According to bivariate categorical analysis, six highly significant (p<0.001) animal- and farm-level risk factors for sheep were age, breed, number of lambings, history of abortion, rural farms, and presence of dogs on the farm. In goats, five significant risk factors were found: History of abortion, separate sheds, dogs on the farm, weekly veterinary consultation, and lack of brucellosis awareness. In a logistic regression model, abortion (OR adjusted 10.8, 95% CI 1.2-96.12), rural farms (OR adjusted 8.5, 95% CI 3.6-20.0), and absence of separate sheds on the farms (OR 1.9, 95% CI 1.1- 3.5) were found to be significant risk factors for ovine brucellosis. Conclusion: The use of complementary measures to tackle the multiple animal- and farm-level risk factors may help to reduce the disease burden in the absence of a vaccination policy for small ruminants in India.