First Insight into Molecular Epidemiology of Tuberculosis Infection in Slaughtered Sheep Intended to Human Consumption in Cameroon: The Case of New-Bell’s Slaughterhouses

Abstract

Objective: Tuberculosis (TB) remains understudied in Cameroonian sheep which are very consumed by human beings and which nevertheless live in close contact with cattle in which TB remains endemic. We carried for the first time a six months descriptive cross sectional study on slaughtered sheep in the major slaughterhouse of Douala, from November 2013 to April 2014. Methods: About 2922 slaughtered sheep were successively inspected for tuberculosis through visual examination and palpation of carcasses, lungs, livers, hearts, intestine, inner carcasses and lymph nodes. Ziehl-Neelsen staining, culture on Lowenstein Jensen solid media supplemented with Pyruvate or Para Nitro Benzene (PNB) and molecular techniques (Genotype Mycobacterium CM/AS assay and Spoligotyping) were used to identify atypical mycobacteria and Mycobacterium tuberculosis Complex (MTBC) species. Results: From the 2922 sheep slaughtered, 810 presented tuberculosis like lesions corresponding to an apparent prevalence of 27.72% (810/2922). Ziehl-Neelsen examination confirmed Acid fast bacilli in 77.78 % (630/810) of cases, corresponding to apparent prevalence of 21.56%. Liver was significantly the most affected by tuberculosis like lesion with 40.74% of case (χ2=67.02, p<0.0001). The use of para-nitro-benzoïc acid showed that 10.74% of all detected cases are caused by atypical mycobacteria, for which molecular typing identified, Mycobacterium fortuitum, Mycobacterium interjectum and Mycobacterium sp. Moreover, spoligotyping reveals that 4.44% of cases were due to M. tuberculosis represented by it ubiquitous T lineage SIT53. No M. bovis or M. caprae were identified. Conclusion: This result shows implication of M. tuberculosis and the high prevalence of atypical mycobacteria in sheep intended for human consumption in Cameroon.