Prevalence and risk factors for bovine tuberculosis in the State of Bahia, Brazil

An epidemiological study was carried out in order to characterize the bovine tuberculosis situation and to support the planning and implementation of the National Program for the Control and Eradication of Bovine Tuberculosis in the State of Bahia, owing to the importance of the disease in causing economic burdens and its impact on public health. The State was divided into four regions. In each region, properties were randomly chosen and, a pre-established number of animals was also randomly selected; these animals then subjected to the intradermal comparative cervical tuberculin diagnostic test. Animals with inconclusive test results were retested with the same diagnostic procedure within a minimum interval of 60 days. Within each sampled property, a questionnaire was administered to verify possible risk factors for the disease. In the State, the prevalence of infected herds was 1.6% [1.0-2.6] and that of infected animals 0,21% [0,07; 0,60]. In the regions, the prevalence of infected herds and infected animals were, respectively, 2,0% [1,0; 4,2%] and 2,0% [1,0; 4,2%] in region 1;, 2,9% [1,5; 5,5] and 0,66% [0,20; 2,16] in region 2; 0,3% [0,04; 2,1] and 0,02% [0,002; 0,12] in region 3; and 0,6% [0,2; 2,5] and 0,05% [0,01; 0,20] in region 4. The risk factors associated with tuberculosis infection were dairy farm (odds ratio [OR] = 9.72) or mixed farm (OR = 6.66), and size of herd >= 18 cows >= 24 months of age (OR = 8.44). In conclusion, it is recommended that the State of Bahia implement a surveillance system for the detection of herds with bovine tuberculosis to certifying them in free herds, with special attention to dairy properties, and develop a solid program of health education so that producers test animals for bovine tuberculosis before introducing them into their herds.