Prevalence and risk factors associated with bovine tuberculosis in local and crossbred dairy cattle in Debre Berhan milk shed, central Ethiopia

Bovine tuberculosis is a chronic and contagious disease of animals and humans with worldwide distribution. A cross-sectional study was employed to estimate the prevalence of bovine tuberculosis and its associated risk factors in dairy cattle found in the Debre Berhan milk shed. The study covered three districts found in the Debre Berhan milk shed for the duration of six months extending from July to December 2018. A single intradermal comparative cervicaltuberculin test was used as a screening test of bovine tuberculosis. Face-to-face interview using a structured questionnaire was also employed to collect data on the risk factors associated with bovine tuberculosis. A binary logistic regression statistical model was used for data analysis. The finding showed that the apparent individual animal level prevalence was 17% (106/625; 95% confidence interval [CI]: 14.2-20.2) at ≥ a 4mm cut-off value in 625 heads of dairy cattle tested. The herd prevalence was 16.7% (16/96; 95% CI: 10.1-26) at ≥ a 4mm cut-off value in 96 dairy herds tested. Multivariable logistic regression analysis at ≥ a 4mm cut-off value revealed that dairy cattle in poor body condition (Adjusted Odd ratio [AOR] = 3.7; 95% CI: 1.6-8.4; p = 0.002), large herd size (AOR = 29.5; 95% CI: 5.6-154.1; p = 0.000) and exotic breed (AOR = 3.7; 95% CI: 1.3-10.7; p = 0.018) had 4, 30 and 4 times the odds of tuberculin positivity with statistical significance, respectively compared to their counterparts. The findings in this study complement the works of other authors who conducted bovine tuberculosis studies elsewhere in Ethiopia. In conclusion, the prevalence of bovine tuberculosis in dairy cattle of Debre Berhan milk shedwas found to be moderately high both at animal and herd levels. Moreover, poor body condition, herd size, and breed were important predictors of tuberculin test positivity. A further in-depth study on the prevalence and associated risk factors using a larger sample size are recommended.