A multi-pronged approach for diagnosis of Brucella melitensis infection in sheep flocks

Abstract

Isolation, serological tests and molecular methods were adopted for the diagnosis of brucellosis in sheep flocks with history of reproductive disorders. Three serological tests RBPT, STAT and iELISA were employed to screen 527 sheep from 6 farms. Among serological tests, iELISA detected higher positives (14.80%), than RBPT (5.88%) and STAT (4.17%). Brucella melitensis was isolated from 6 of 33 seropositive sheep and none from seronegative animals. All the isolates were identified as B. melitensis by biochemical tests and confirmed by genus and species specific - AMOS PCR. None of the isolates yielded products of 285bp, 976bp and 498bp specific for B. suis, B. ovis and B. abortus, respectively. Of the 33 seropositive sheep, the bcsp31genus specific amplicon of 223bp was observed in 26 vaginal, 6 serum and 2 in blood samples. Vaginal samples was found suitable clinical sample for the isolation and PCR, followed by serum and blood. Different diagnostic approaches used in the present study are of value as anti Brucella antibodies and antigen were detected confirming the disease in sheep flock. This practically oriented approach is of immense importance, as it enables to institute the control strategies at the earliest.