Sero‐prevalence and risk factors of Brucella presence in farm bulk milk from open and zero grazing cattle production systems in Rwanda

BACKGROUND: Animal and human brucelloses have been reported in Rwanda, human brucellosis being linked to drinking inadequately heat‐treated milk. However, information on Brucella detection and prevalence in milk produced in Rwanda is limited. OBJECTIVES: To determine the sero‐prevalence and risk factors of Brucella in farm bulk milk from zero and open grazing cattle production systems in Rwanda. METHODS: A total of 330 farm bulk milk samples were collected from 198 zero grazing farms and 132 open grazing farms in a cross‐sectional study in Rwanda. Sero‐prevalence of Brucella in milk was analysed using indirect enzyme‐linked immunosorbent assay. A questionnaire was administered to farmers to determine the risk factors of milk contamination with Brucella. RESULTS: Anti‐Brucella antibodies were prevalent in 19.7% (95% confidence interval (CI), 15.5–24.4) of the 330 collected farm bulk milk. Sero‐prevalence was significantly higher (p < 0.05) in open grazing farms (37.9% [50/132]) than in zero grazing farms (7.6% [15/198]). Practising open grazing system (odds ratio, OR = 69.5; 95% CI = 1.6–3033.6), history of abortion (OR = 19.5; 95% CI = 8.1–46.8) and placenta retention (OR = 4.2; 95% CI = 1.7–10.3) were the significant risk factors for the presence of anti‐Brucella antibodies in milk. CONCLUSION: Notably, more than a third of farm bulk milk from open grazing farms in Rwanda contains Brucella antibodies. Considering the zoonotic nature of Brucella, there is a need to reinforce brucellosis control programs in the country.