Predictors of specific anti-Brucella antibodies among humans in agro-pastoral communities in Sengerema district, Mwanza, Tanzania: the need for public awareness

BACKGROUND Human brucellosis remains to be a neglected zoonotic disease among agro-pastoral communities where livestock rearing is one of the main economic activities. This study was conducted in different agro-pastoral communities in Sengerema district, Mwanza, Tanzania, to determine seroprevalence and predictors of anti-Brucella antibodies, information that may influence public awareness on the risk factors and strategies to improve the diagnosis of brucellosis in developing countries. METHODS A cross-sectional community-based study was conducted between July and September 2008 in ten villages of Sengerema district. Sociodemographic and other related information were collected using a standardized data collection tool. Detection of Brucella abortus and Brucella melitensis antibodies were done using rapid Brucella serum agglutination test. Data were analysed by using STATA version 11.0. Adjusted odds ratios (AOR) were calculated using multivariate logistic regression analysis. RESULTS A total of 382 adults were enrolled with the median age of 30 (interquartile range 15-40) years. Males formed the majority of the participants 234 (61.5 %). Overall, seroprevalence of anti-Brucella antibodies was found to be 14.1 % (54/382, 95 % CI 10.6-17.5). Seroprevalence of B. melitensis was 11 % (42/382) while that of B. abortus was found to be 7 % (26/282), P = 0.0267. Co-infection of B. melitensis and B. abortus was observed in 3.6 % (14/382, 95 % CI 1.7-5.4) of participants. On a multivariate logistic regression analysis, male sex (AOR 3.2, 95 % CI 1.3-7.5, P = 0.007), touching goat placenta (AOR 2.54, 95 % CI 1.05-6.14, P = 0.012) and agro-pastoralist occupation (AOR 2.07, 95 % CI 1.01-4.24, P = 0.04) were found to predict B. melitensis infection. Males (AOR 3.07, 95 % CI 1.45-6.51, P = 0.003) and agro-pastoralists (AOR 2.98, 95 % CI 1.38-6.43, P = 0.005) were found to be predictors for specific anti-Brucella antibodies. CONCLUSIONS A significant proportion of the agro-pastoralist male population in agro-pastoral communities in Sengerema district is positive for anti-Brucella antibodies. With the decrease incidence of malaria fever, other causes of fever such as Brucella spp. should be considered of public health concern in Tanzania especially in agro-pastoral communities.