Risk factors and control strategies for Brucella spp. and RB51 vaccine shedding in buffalo milk: A cross-sectional study

Brucellosis is prevalent in water buffaloes, which serve as significant reservoirs. The disease adversely affects meat and dairy products and can be transmitted to humans through contaminated products. This study aimed to determine the risk factors and control strategies for Brucella spp. and RB51 vaccine shedding in raw buffalo milk. A cross-sectional study was conducted across 261 farms where only 182 out of 261 farms received regular vaccinations through PCR tests and a questionnaire survey. The survey addressed potential risk factors and farm management. Univariable and multivariable logistic regression analyses were used to analyze the associated risk factors, represented as odds ratios (OR) with 95 % confidence intervals. The PCR survey revealed a 35.2 % prevalence of Brucella spp at the household level and 30.8 % at the buffalo level. Significant risk factors for Brucella PCR-positivity included the number of buffaloes in a household (OR = 1.512, 95 %CI: 1.107-2.065, p = 0.009) and the presence of resident dogs (OR = 2.157, 95 %CI: 1.053-4.417, p = 0.036). Regular vaccination practices were identified as a preventive factor (OR = 0.304, 95 %CI: 0.172-0.537, p <0.001). No animal-level risk factors were identified, and reduced-dose brucellosis vaccination showed a protective effect. Higher buffalo numbers in a household correlated with increased vaccine shedding in milk (OR= 2.489, p-value <0.001). Shedding was lower in households with primary education farmers than those without education (OR=14.163, p-value <0.001). Borrowing bulls for insemination also increased shedding (OR=13.266, p-value= 0.015). The study highlights the need for targeted control strategies, emphasizing education, vaccination, and hygiene practices to mitigate brucellosis's impact on buffalo and human populations.