A prevalence study of bovine tuberculosis by using abattoir meat inspection and tuberculin skin testing data, histopathological and IS6110 PCR examination of tissues with tuberculous lesions in cattle in Ethiopia

Post mortem surveillances, for the detection of tuberculous lesions in particular depend on the work load time and the diligence of the inspector conducting the examination. The first aim of the study was to determine the trend of occurrence of tuberculous lesions in two abattoirs in Addis Ababa and Debre-Zeit (Ethiopia). The second aim of the study was to determine prevalence of the tuberculin skin test results in 10 dairy farm areas in Addis Ababa. The third aim was to detect tuberculous lesions and causal agents from tissue samples of the respiratory tract and mesenteric lymph nodes of the slaughtered cattle. The ten year (1996–2005) retrospective analysis of the meat inspection of 2 455 289 slaughtered animals showed that 707 (0.028%) were found with tuberculous lesions in parenchymatous organs of which were 699 (0.052%) of 1 336 266 cattle, 4 (0.001%) of 534 436 sheep, 3 (0.001%) of 573 767 goats and 1 (0.009%) of 10 820 pigs. The tuberculous lesions found in cattle were statistically highly significant (P < 0.01) than in other animals. The bovine tuberculin skin tests were conducted in Addis Ababa in 10 farm areas in 85 dairy farms having 2 098 cattle. Positive reactions were obtained from 9 farm areas in 41 (48%) herds which included 392 (19%) of the animals. In a current study, tuberculous lesions were found in 34 (3.5%) animals by the meat inspection surveillance of 984 cattle. Histopathologically, granulomatous inflammation was evident in 3 (8.8%) animals with tuberculous lesions. A highly sensitive PCR (IS6110) was positive in 4 of 34 (11.8%) animals with tuberculous lesions and in 1 (2.9%) of animal without lesions. The analyzed data and these study findings indicated that tuberculosis in cattle is an existing problem in Ethiopia which needs to be solved.