Bovine Brucellosis in India: Etiology, Epidemiology, Diagnosis, Control, and Zoonotic Implications: A Literature Review

Bovine brucellosis is an economically important infectious and zoonotic disease that adversely affects livestock productivity, reproductive performance, and public health in India. It is caused predominantly by Brucella abortus, a Gram-negative, facultative intracellular bacterium that primarily affects cattle and buffaloes. This review synthesizes the available literature on the etiology, epidemiology, clinical manifestations, transmission dynamics, diagnostic approaches, economic impact, control strategies, and zoonotic implications of bovine brucellosis in India. National serological surveys have demonstrated considerable geographical variation in disease prevalence, with several studies reporting higher seropositivity in cattle than in buffaloes and increased risk in organised dairy farms, larger herds, and animals with a history of abortion or repeated breeding. The principal clinical manifestations include late-term abortion, stillbirth, retained placenta, infertility, and reduced milk production, resulting in substantial economic losses to livestock farmers. Transmission occurs mainly through contact with infected aborted materials, uterine discharges, contaminated environments, and consumption of contaminated milk. Diagnosis relies primarily on the Rose Bengal Plate Test (RBPT) and enzyme-linked immunosorbent assay (ELISA), while bacteriological isolation and molecular techniques provide additional confirmation and characterization. However, cross-reactivity in conventional serological tests, biosafety requirements for bacterial isolation, and difficulties in differentiating vaccinated from naturally infected animals remain important diagnostic challenges. India's control programme emphasizes calfhood vaccination with B. abortus strain 19 (S19), supported by surveillance, biosecurity, and farmer awareness initiatives under the National Animal Disease Control Programme (NADCP). Despite these efforts, limitations associated with incomplete surveillance, informal milk marketing, inadequate awareness, and practical constraints on the removal of infected animals continue to hinder effective disease control. A One Health approach integrating veterinary services, public health authorities, improved diagnostic technologies, and community-level interventions is essential. Future research should prioritize representative national surveillance, affordable and reliable differentiation of infected and vaccinated animals, evaluation of vaccination coverage, and evidence-based control strategies suited to India's diverse production systems. Strengthening these measures is crucial for reducing livestock-associated economic losses and minimising the risk of human brucellosis.