Mycobacterium bovis Isolates from Tuberculous

n Chad, prevalences of tuberculin-positive cattle are 0.8% (95% confidence interval (CI) 0.2%-1.4%) in the east (Ouaddaï region) (1) and 16.9% (95% CI 10.4%-23.5%) in the west (Chari-Baguirmi and Kanem regions) (2). The latter comparative intradermal tuberculin study was conducted with 34 additional transhumant herds; a prevalence of 11.5% (CI 6.9%-18.5%) was found when herds were considered as random effect in the model. More tuberculin reactors were found among Mbororo than Arab zebus (p = 0.02). In the slaughterhouse of Farcha in N'Djaména, 90% of slaughtered cattle are of the Arab zebu breed, 7% Mbororo zebu, and 3% Kouri (3). Previous slaughterhouse studies showed that bovine tuberculosis (TB) is an important cause of condemnation (i.e., if a car- cass is fully condemned, the whole carcass is destroyed (≈9% of all inspected cattle carcasses)) (4). A retrospective study on causes of condemnation after meat inspection showed that most carcasses with tuberculous lesions were detected from July to November and that more Mbororo cattle than other breeds had TB-like lesions (42/60 vs. 132/1,539) (5). The diagnosis of suspected bovine TB was based on sighting of typical macroscopic lesions of the organs during meat inspection. In Chad, until this study was undertaken, bovine TB was not confirmed by isolation or molecular characteriza- tion of the causative agent, Mycobacterium bovis. This organism is recognized as a zoonotic pathogen that infects many persons, particularly in the developing world. The highest prevalence of coinfection with bovine TB and HIV/AIDS is also in the developing world (6). Our study was aimed at isolating the first M. bovis isolates from spec- imens of Mbororo and Arab cattle in the newly setup mycobacteriology unit of the veterinary laboratory of Fracha, at characterizing the isolates with molecular meth- ods, and at comparing the isolates with those from Cameroon (7).