Risk factors associated with the occurrence of Brucella canis seropositivity in dogs within selected provinces of South Africa

The growing population of free-roaming dogs in informal communities in South Africa may increasingly place humans at risk of possible zoonotic infections including, but not limited to, Brucella canis. Worldwide, the prevalence of B. canis infection has increased during the last two centuries, resulting in increased reports of dog and human infections. This study investigated the risk factors associated with B. canis infection in dogs in three predefined areas: Gauteng, the Eastern Cape and Western Cape provinces, of South Africa. Dogs aged 7 months and older presented to welfare organisations and breeders in the study areas were selected for sampling. A comprehensive questionnaire on dog ownership, general health and vaccination status was completed prior to sampling. One blood sample of 8 mL was collected aseptically per dog. Then, equal amounts (4 mL) were transferred to the different vacutainer tubes. The 2-mercaptoethanol-tube agglutination tests were used after validation. Fifty-two dogs out of the combined sample of 1191 dogs from the three study areas tested positive for B. canis, representing an overall occurrence of 4.4%. A binomial logistic regression model was fitted to identify risk factors associated with B. canis in dogs within the study areas. Dog age (0.371; p < 0.05) and external parasite infestation (0.311; p < 0.05) were significantly associated with the B. canis infection. Ownership and sterilisation need to be further investigated as possible risk factors because both had odds ratios of 1684 and 1107, respectively, in the univariate model.