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Brucellosis is endemic in Tanzania. A cross-sectional study was conducted at 17 cattle farms in agro-pastoral areas in Tanzania to identify risk factors associated with the within-farm prevalence of bovine brucellosis and to quantitatively assess the infection dynamics through disease modelling. Cattle blood sampling and interviews with farmers using a structured questionnaire were conducted. A total of 673 serum samples were screened using the Rose-Bengal plate test (RBPT), and sero-positivity of RBPT-positive samples was confirmed using a competitive enzyme-linked immunosorbent assay. Zero-inflated binomial regression was performed for univariable and multivariable risk factor analyses of within-farm prevalence. Several susceptible-infectious (SI) models were compared based on deviance information criteria, and age-dependent force of infection (FOI) was measured using age-specific prevalence data for the 10 infection-positive farms. Using the diagnoses of cows on the 17 farms, the basic reproduction number, R 0 , was also calculated. The farm-level prevalence and animal-level adjusted prevalence were 58.8 % (10/17, 95 % confidence interval: 33.5-80.6 %) and 7.0 % (28/673, 95 % credible interval: 5.7-8.4 %), respectively. The risk factor for high within-farm prevalence was introduction of cattle from other herds. A mathematical model with constant FOI showed the annual probability of infection as 1.4 % (95 % credible interval: 1.0 %-2.0 %). The R 0 was 1.07. The constant FOI could have been due to the predominant mode of infection being transmission of Brucella from contaminated aborted materials during grazing. Direct purchase of infected cattle could facilitate efficient transmission between susceptible animals through abortion., (Copyright © 2021 The Author(s). Published by Elsevier B.V. All rights reserved.)

The prevalence of bovine tuberculosis (BTB) infection in cattle was investigated in pastoral and intensive production systems in the eastern zone of Tanzania. The prevalence of BTB infection as determined by single comparative intradermal tuberculin test (SCITT) was 1.3%, whereas the non-specific infection prevalence was 6%. In the pastoral sector, the prevalences were 1 and 7%; under intensive systems, they were 2 and 6% for BTB and non-specific infections, respectively. The prevalences were significantly higher in the intensive than pastoral production systems. However, the prevalence of BTB infection was higher in the small-scale (3%) than in other production systems (0.6-1.1%). Non-specific infections were lowest in the small-scale dairy sector (4%) than in other dairy-production systems (6-11%). Out of 143 herds tested, 10 and 28% of herds in the intensive systems (small, medium and large farms) and 17 and 88% of the herds in the extensive system (pastoral farms) had both BTB and non-specific infections, respectively.