A cross-sectional study of bovine tuberculosis in dairy farms in Asmara, Eritrea

Bovine tuberculosis in dairy cattle in Asmara, Eritrea, was studied using a cross-sectional study to describe its prevalence and to identify factors associated with it. A total of 72 randomly selected herds were included in the study. The comparative intradermal tuberculin test was used for the diagnosis. Of 1813 individual animals tested, 14.5% were reactors. Thirty herds (41.7%) had at least one reactor but, by defining a reactor herd as any herd with two or more reactors, only 19 (26.4%) herds were classified as reactor herds. Based upon individual animal specificity of 98.5%, the calculated herd specificity was > 99%. A multiple logistic model showed that the presence of exotic breeds was associated with a high risk (odds ratio = 5.70; 95% confidence interval 1.13-28.8). An increased risk was also linked to large herds. Keeping the animals always indoors reduced the risk, but could not be fitted to the model owing to empty cells.