Work

Integrated Molecular Detection and Epidemiological Investigation of Brucella abortus in Dairy Cattle and Farm Workers During a Brucellosis Outbreak

Year: 2026

Type: article

Abstract: BACKGROUND: Brucellosis is a highly contagious zoonotic disease caused by bacteria belonging to the genus Brucella that can infect a wide range of domestic and wild animals. A recent brucellosis outbreak was reported at a dairy farm in the peri-urban region of Khanewal District, Punjab, Pakistan. OBJECTIVE: In response, this study aimed to improve understanding of the dynamics of Brucella abortus infection in cattle and dairy farm workers in the local context. METHODS: In November 2024, a total of 83 cattle, representing six different breeds, along with blood samples from 11 farm workers directly involved in handling these animals, were sampled. Relevant epidemiological data were also collected to support the investigation. To detect Brucella infection in cattle, both the Rose Bengal Plate Test (RBPT) and polymerase chain reaction (PCR) targeting the IS711 gene were employed. RESULTS: All sampled cattle tested seropositive for Brucella antibodies by RBPT, indicating widespread exposure to Brucella. Molecular detection through partial IS711 sequence amplification revealed that 48% of the cattle and 45% of the farm workers (5 out of 11) tested positive for Brucella spp. INFECTION: Subsequent DNA sequencing and BLAST analysis confirmed the presence of B. abortus in both cattle and humans. The obtained IS711 sequences closely matched those previously reported in ruminants and humans in China. Data analysis further showed that cows were more susceptible to B. abortus infection compared to bulls (p = 0.01). However, no significant association was observed between infection status and cattle breed, age, presence or absence of ectoparasites, or history of abortion (for all p > 0.05). CONCLUSION: The present study provides evidence of B. abortus detection among cattle at the investigated dairy farm in Khanewal. The findings should be interpreted within the context of the studied farm, as the purposive sampling of a single dairy farm does not permit extrapolation to the wider cattle population of Khanewal District or Pakistan. Further multi-farm studies involving geographically diverse cattle populations are warranted to determine the broader occurrence and epidemiological pattern of B. abortus.

Source: Veterinary Medicine and Science

DOI: 10.1002/vms3.71329