Epidemiological status of bovine tuberculosis in the state of Minas Gerais, Brazil, 2013

A cross sectional study was performed to assess the epidemiological status of bovine tuberculosis in the state of Minas Gerais, Brazil, in 2013. The state was divided into seven regions, and a preset number of herds was randomly sampled in each region. From each farm, female cattle aged 24 months or older were randomly sampled and subjected to the comparative cervical tuberculin test (CCTT). Animals with inconclusive test results were re-tested with the same diagnostic procedure after a minimum interval of 60 days. A total of 31 832 animals were tested from 2 182 farms. An epidemiological questionnaire was administered in the farms to identify risk factors associated with bovine tuberculosis. Prevalence in the state was estimated at 4.25% (95% CI: 3.36% - 5.15%) for herds and at 0.56% (95% CI: 0.46% - 0.66%) for animals. Data on herd prevalence for bovine tuberculosis for each stratum showed the highest prevalences at region Sul e Sudoeste (stratum 5) and region Central (stratum 3) which were significantly different from the lowest prevalences found at regions Noroeste, Norte e Nordeste (stratum 1) and region Leste (stratum 2). The highest animal prevalences observed for the region Sul e Sudoeste (stratum 5), region Zona da Mata (stratum 4) and region Central (stratum 3) were significantly different from the lowest ones at region Triangulo Mineiro (stratum 7), region Noroeste, Norte, e Nordeste (stratum 1) and region Leste (stratum 2). The presence of bovine tuberculosis was associated with animal purchase from cattle traders (OR = 2.59 [95% CI: 1.28 - 5.20]), higher yield intensive dairy (OR = 7.55 [95% CI: 1.89% - 30.09%]) and non-intensive dairy production (OR = 3.58 [95% CI: 1.06% - 12.04%]), as well as with herds with 30 or more cows (OR = 1.97 [95% CI: 1.02 - 3.80]). Non-specific reactors to the CCTT were found in 95.07% (95% CI: 94.05% - 96.09%) of the herds. Therefore, the state of Minas Gerais should implement surveillance systems for the detection and sanitation of infected herds, preferably incorporating risk-based surveillance elements, considering the results of the present study.