A study on bovine brucellosis in an organized dairy farm

Aim: To assess the status of bovine brucellosis in an organized dairy with a past history of Brucella abortions and where Brucella control measures including test and removal, calf-hood vaccination (already present adult animals were not vaccinated), use of semen obtained from a screened bull and general hygienic measures helps in the control of brucellosis in the farm have been implemented for the past four years. Materials and Methods: A total of 195 samples including 89 blood samples, 89 serum samples and 17 milk samples were collected and analysed by isolation and identification, Polymerase chain Reaction (PCR), Milk Ring Test (MRT), Rose Bengal Plate Test (RBPT), Standard Tube Agglutination Test (STAT) and Enzyme Linked Immnuno-Sorbent assay (ELISA). Results: On analysis, all the 89 blood and 17 milk samples turned out to be negative for culture and PCR. MRT and ELISA tests on all the 17 milk samples and STAT on all the 89 serum samples were also negative. The percent positives for Brucella antibodies in serum samples were 4.5 and 6.7 by RBPT and ELISA, respectively. Of the 17 vaccinated animals, 14 were negative by all the Brucella antigen and antibody diagnostic tests employed. Amongst the three vaccinated animals, one animal was positive by RBPT and I-ELISA and, two animals were positive by I-ELISA alone. On the other hand, of the 72 nonvaccinated animals, 65 were negative by all the diagnostic tests employed, three animals were positive by RBPT and 4 animals were positive by I-ELISA. Conclusion: The results of our study indicated that a combination of RBPT and I-ELISA can be successfully used for screening for brucellosis when the prevalence is low. Implementation of control measures including test and removal of the affected, calf-hood vaccination, use of semen obtained from a screened bull and general hygienic measures help in the control of brucellosis in the farm. Keywords: bovine brucellosis, control programmes, diagnostic tests, ELISA, organized dairy farm, RBPT