Mycobacterial infections in carcasses of ruminants slaughtered at the two slaughterhouses of Kassala, Sudan

Tuberculosis (TB) is a chronic bacterial disease of humans and animals. It is characterized by the progressive development of specific granulomatous lesions in affected organs. Human TB is endemic in Eastern Sudan. However, knowledge on the epidemiology of TB in ruminants is scarce. In a six-month study from June to November 2014, a total of 2304 carcasses of cattle, sheep, goats and camels slaughtered at the East and West Gaash slaughterhouses of Kassala were inspected to investigate TB prevalence. Only 0.1% (n = 2) of the carcasses had suspicious TB lesions. These lesions were solely found in carcasses of sheep, in the liver, lungs, and peritoneal cavity. The samples collected from the lesions were investigated for the presence of mycobacteria, which were found in one of the two carcasses. The grown bacteria were subjected to a line probe assay (GenoType Mycobacterium CM), and to 16S rDNA and ITS gene sequencing, and whole genome sequencing (WGS). However, none of these methods identified this isolate as a valid Mycobacterium species. Nevertheless, 16S sequence allocated this isolate to slow growing mycobacteria. Neither Mycobacterium bovis nor M. caprae nor M. tuberculosis were found in the collected granulomatous lesions. In conclusion, the overall prevalence of TB-suggestive lesions in ruminants in Kassala was very low. Extended studies combining the use of a tuberculin skin test and slaughterhouse-based investigations should be adopted for TB surveillance in ruminants in Sudan.