Serological and molecular study on caprine brucellosis in Puducherry (India) and its public health significance

Caprine brucellosis due to Brucella melitensis is an important zoonotic disease. The present study was carried out to address the lack of a comprehensive study on the status of caprine brucellosis in Puducherry, India using serological and molecular tests in goats and to assess the seroprevalence in human risk groups of the aforementioned region to ascertain the public health significance of the disease. Seroprevalence in 120 goats was found to be zero, 3.33% and 18.33% by Rose Bengal agglutination Test (RBT), Standard Tube Agglutination Test (STAT) and Immunoglobulin G Indirect Enzyme Linked Immune Sorbant Assay (IgG iELISA) respectively. Of the 120 goat genital swabs screened, while conventional polymerase chain reaction (PCR) detected genus specific 16S rRNA and Brucella melitensis specific omp2 genes in 17.50% and 5.00% of samples respectively, the OMP31TaqMan® real time PCR with a positive detection of 40.00% was both the most sensitive and specific for detection of Brucella melitensis. The study provides insight into the optimization of diagnostic tests following cluster wise sampling for brucellosis in goats. The strain of Brucella melitensis in Puducherry was found to be Biovar 3 based upon suggestive results of Restriction Fragment Length Polymorphism (RFLP) of omp2 gene product. Seroprevalence by IgG iELISA was 33.33 % in 30 samples from human subjects. Serological evidence of caprine brucellosis in goats and human subjects and molecular detection of Brucella melitensis in Puducherry, India warrants regular screening, surveillance and reporting of disease in goats and human risk groups.