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Herd-level risk factors associated with Brucella sero-positivity in cattle, and perception and behaviours on the disease control among agro-pastoralists in Tanzania

Asakura, Shingo, Makingi, George, Kazwala, Rudovick, Makita, Kohei
Acta tropica 2018
Brucella, One Health initiative, agropastoralism, blood, brucellosis, calves, cows, cross-sectional studies, disease control, drinking, enzyme-linked immunosorbent assay, factor analysis, farmers, farms, hands, health education, health promotion, herds, human diseases, humans, linear models, milk, questionnaires, raw milk, risk behavior, risk factors, seroprevalence, surveys, vaccination, vaccines, veterinary services, willingness to pay, Tanzania
Brucellosis is endemic in Tanzania, particularly in agro-pastoral areas. This study investigated the herd-level sero-prevalence and risk factors for Brucella sero-positivity in cattle, and perception and behaviours associated with brucellosis control among agro-pastoralists in Morogoro Region, Tanzania. A cross-sectional study involving herd milk diagnosis by indirect enzyme-linked immunosorbent assay and questionnaire survey was conducted in 124 farms. Questions included potential risk factors, knowledge of brucellosis, willingness-to-pay for cattle vaccination, and item count technique (ICT) for selling behaviour of cows that experienced abortion. Risk factor analysis for Brucella sero-positivity in cattle and analysis of factors associated with willingness-to-pay were conducted using classical tests and generalised linear models. Most farmers had little knowledge about brucellosis (disease name: 13.7%, symptoms: 3.2%, transmission from cattle to human: 2.4%, and Brucella vaccine: 2.4%). The proportion of Brucella sero-positive herd was 44.4% (55/124, 95%CI: 35.5–53.5). No risk factors for Brucella sero-positivity were identified; however, using a veterinary service was identified as a preventive factor (OR = 0.39, 95%CI: 0.18–0.84, p = 0.02). For scenarios of vaccinating all cattle and only calves, 59.7% and 89.5% of farmers were willing to pay for vaccination, respectively. Being a Maasai tribe member was a hesitating factor for vaccinating all cattle (OR = 0.39, 95%CI: 0.19–0.83, p = 0.01) and using a veterinary service was an encouraging factor for vaccinating calves (OR = 4.0, 95%CI: 1.2–13.0, p = 0.02). The ICT found that 45.1% of farmers sold cows that experienced abortion. This estimate was not statistically different from that obtained by direct questioning (34.1%, SE = 7.5%, binomial p value = 0.27, factor score = 1.32), suggesting that farmers did not hesitate to sell such cows. The Maasai conducted more risky behaviours for human infection such as drinking raw milk (p = 0.06) or blood (p < 0.01) and helping delivery with bare hands (p = 0.03) than other tribes. Community-based brucellosis control programmes with calf vaccination may be feasible in the study areas. A One Health approach including the promotion of health education and expansion of veterinary services is crucial for disease control.