Seroprevalence and Associated Risk Factors of Bovine Brucellosis among Cattle and Buffaloes in District Khairpur, Sindh, Pakistan

Abstract

Bovine brucellosis is an important reproductive and zoonotic disease that affects livestock productivity and may also pose a health risk to people who have close contact with infected animals or their products. Although brucellosis has been reported from several regions of Pakistan, district-specific information from Khairpur, Sindh, remains limited. The present study was therefore conducted to determine the seroprevalence of bovine brucellosis and evaluate selected animal- and management-related risk factors among cattle and buffaloes in District Khairpur. A cross-sectional study was conducted in eight sampling areas of District Khairpur, namely Faiz Ganj, Gambat, Khairpur, Kingri, Kot Diji, Mirwah, Nara and Sobhodero. A total of 200 blood samples were collected, comprising 100 cattle and 100 buffaloes, with 25 samples obtained from each sampling area. Serum samples were initially screened using the Rose Bengal Plate Test (RBPT), while RBPT-positive samples were subsequently examined by enzyme-linked immunosorbent assay (ELISA) at the Sindh Institute of Animal Health, Karachi. Information regarding sex, age, abortion history, herd size, breeding method, grazing system and introduction of new animals was collected through a structured questionnaire. Associations between seropositivity and categorical variables were evaluated statistically, with P < 0.05 considered significant. Of the 200 animals examined, 16 (8.0%) were positive by RBPT and 13 (6.5%) were confirmed positive by ELISA. ELISA-based prevalence was 6.0% in cattle and 7.0% in buffaloes, with no significant difference between species (P = 0.774). Seropositive animals were detected in all eight sampling areas, with area-specific prevalence ranging from 4.0% to 8.0% (P = 0.887). Females showed significantly greater seropositivity than males (8.0% vs. 2.0%; P = 0.041). Prevalence increased with age, reaching 10.0% in animals aged ≥7 years (P = 0.032). A strong association was observed with abortion history, with prevalence of 15.0% among animals with a previous abortion history compared with 2.86% among those without such history (P = 0.003). Large herds showed higher seropositivity (11.67%) than small herds (2.86%; P = 0.021). Natural mating, communal grazing and introduction of new animals were also significantly associated with seropositivity (P = 0.048, 0.038 and 0.044, respectively). Bovine brucellosis was present among cattle and buffaloes in District Khairpur, with an overall ELISA-confirmed seroprevalence of 6.5%. The findings indicate that both animal-related and management-related factors contribute to the occurrence of infection. Regular surveillance, screening of newly introduced animals, improved reproductive management, safer handling of abortion materials and farmer awareness are recommended to reduce transmission and associated livestock and public-health risk.