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

Acta Trop. 2018 Nov:187:99-107. doi: 10.1016/j.actatropica.2018.07.010. Epub 2018 Aug 1.

Abstract

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.

Keywords: Brucellosis; Community-based control; Item count technique; Tanzania; Willingness to pay for vaccination.

MeSH terms

  • Adult
  • Animals
  • Brucella / immunology*
  • Brucellosis / epidemiology*
  • Brucellosis / prevention & control*
  • Cattle
  • Cross-Sectional Studies
  • Disease Eradication / methods*
  • Farmers / psychology*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Milk / parasitology*
  • Pregnancy
  • Prevalence
  • Risk Factors
  • Seroepidemiologic Studies
  • Surveys and Questionnaires
  • Tanzania / epidemiology
  • Vaccination*