Re-emergence of Bovine Brucellosis in Smallholder Dairy Farms in Urban Settings of Tanzania

Abstract

Aims: Brucellosis infection was previously encountered in all livestock farming systems in Tanzania but reported to decline below 2% in smallholder dairy subsector due to the stringent calf-hood vaccination using S19 between 1979 and 1990. However, reports from the last decade indicated an increase of the infection in the smallholder dairy subsector. This prompted several researchers to conduct further studies in different urban settings to ascertain the disease and associated risk factors. This study aims to elucidate the magnitude of brucellosis in urban areas of Morogoro region and related risk factors in the advent of no control intervention in place. Presence of anti-brucella antibodies in dairy animals residing in urban areas may pose a threat to milk consumers in the cities as a significant proportion of the milk is sold informally. Therefore, generating this information will inform policy to formulate feasible intervention for controlling brucellosis in urban settings that indirectly will safeguard public health. Study Design: This was a cross-sectional survey. Place and Duration of Study: The study was conducted in Morogoro Municipality between May and September 2012. Methodology: The study was to determine the prevalence of anti-brucella antibodies in smallholder dairy cattle in urban settings of Tanzania. Milk Ring Test was used as a screening technique while Competitive Enzyme-Linked Immunosorbent Assay was a confirmatory test. A questionnaire was applied to each animal owner. A total of 104 respondents were interviewed to assess possible risk factors associated with re-emergence and transmission of brucellosis among dairy cattle. Results: 390 dairy cows from Morogoro Municipality were screened for Brucella circulating antibodies. Overall 35.4% (95%CI; 25.2-33.8) of milk samples tested positive based on MRT while seroprevalence was 21.3% (95% CI) based on c-ELISA. It was further revealed that abortion (p= 0.01) and herd size (0.05) were significantly associated with brucellosis seropositivity in cattle. Although 32% of herd owners vaccinate their cattle against several transboundary diseases, none vaccinated against brucellosis.  Conclusions: From this study, there is evidence that collapse of the Tuberculosis and Brucellosis Control Programme has resulted into an increase of brucellosis within the smallholder dairy farmers within urban settings. This may pose a high risk to urban farmers and milk consumers thus attracting immediate response.