Serological, cultural, and molecular evidence of Brucella infection in small ruminants in Pakistan.

INTRODUCTION The objectives of the present study were to determine the seroprevalence and identify the causative agent of brucellosis in small ruminants in Pakistan. METHODOLOGY A total of 278 serum and 212 milk samples were collected from sheep and goats that had close contact with seropositive bovine herds. Data related to age, sex, location, and breed were collected on the sampling day. Serum and milk samples were initially screened using two different Rose Bengal plate test (RBPT) antigens and a milk ring test (MRT). Seropositive samples were subjected to bacterial isolation and PCR analysis using Brucella genus-specific (bcsp31) and Brucella species-specific (IS711 for Brucella abortus and Brucella melitensis) quantitative real-time polymerase chain reactions (qRT-PCR). RESULTS Twenty-four (8.6%) serum samples were positive by RBPT. Twenty (9.4%) animals were positive for Brucella antibodies using MRT. No Brucella isolates were obtained from the examined blood and milk samples. Of the 24 seropositive serum samples, 18 (75%) were positive in the Brucella genus-specific (bcsp31) and Brucella abortus-specific (IS711) qRT-PCR, respectively. CONCLUSIONS Brucella abortus was identified as causative agent of ovine and caprine brucellosis in Pakistan. Results of this study can be used for the development of an effective control and eradication strategy for brucellosis in livestock, especially small ruminants.