Cultural and molecular detection of zoonotic tuberculosis and its public health impacts in selected districts of Tigray region, Ethiopia

Abstract

Bovine tuberculosis (BTB) is a chronic infectious disease of animals characterized by the formation of granulomas in tissues and its detection is carried out most commonly on the basis of tuberculin skin testing, abattoir meat inspection and rarely on bacteriological techniques. A study was conducted to assess the epidemiology and zoonotic implication of bovine tuberculosis in three selected districts of Tigray region between September 2012 and June 2013 using Comparative Intradermal Tuberculin (CIDT) test, abattoir surveillance, bacteriology and molecular typing. Besides, livestock owners were interviewed for the evaluation of the zoonotic potential of BTB. On the basis of the CIDT test, animal and herd prevalence were 2.7% (14/524) and 9.3% (13/140), respectively, while in abattoir-based study the prevalence was 22% (117/531). Male animals were more likely (OR= 1.7; P=0.012; 95% CI: 1.12- 2.55) to exhibit tuberculous lesions as compared to female animals. The proportion of culture positivity was 32% (40/125) in tissue samples. Only nine isolates were typed and out of which seven isolates were positive for the genus Mycobacterium of which two were identified as M. tuberculosis. The two M. tuberculosis species had the same spoligotype pattern. Awareness of cattle owners about BTB was poor and detection of BTB both in live and slaughtered animals. The isolation of M. tuberculosis from animal tissues indicates the existence of transmission of this agent from humans to animals. Therefore, there should be practical and sound control methods such as strict meat inspection, boiling of milk and cooking of meat, and public education to raise the awareness on the transmission of the disease.

Keywords: Abattoir , Ethiopia, Mycobacterium, Tuberculosis, Zoonosis