Cross-sectional Study on Bovine Tuberculosis Based on Post Mortem and Bacteriological Examination in Four Abattoirs of Northern Algeria: Slaughterhouses as Source of Data for Disease Control

Bovine tuberculosis (BTB) remains a major zoonotic disease, causing economic losses as well as public health problems, particularly in developing countries.The aim of this study was to determine the prevalence of BTB and the associated risk factors in northern Algeria, based on the cattle population slaughtered in four abattoirs.Overall, 3,546 slaughtered cattle were inspected for detection of visible tuberculosis-like lesions between 2017 and 2019.Furthermore, tissue samples were collected from the affected carcasses (n = 232) and screened using the Ziehl-Neelsen (ZN) staining technique and mycobacterial culture.Visible tuberculosis-like lesions occurred in 6.5% (232/3,546) of the slaughtered animals.Whatever the technique used, the prevalence of BTB disease was found to be statistically associated with age, sex, and breed (p<0.0001).The thoracic lymph nodes including the tracheobronchial and mediastinal LN were mostly affected, at rates of 52.6% and 31.9%,respectively.The majority (69.4%; n = 161) of granulomas found in the thoracic lymph nodes were characterized by caseous necrosis (34%) or caseous-calcified lesions (35.3%).The present study demonstrated that despite the efforts of authorities to eradicate BTB, this disease is still enzootic in Algeria, since the prevalence remains important.Finally, our findings highlighted the importance of abattoirs as a source of information for recording the BTB epidaemiological situation in a given area, contributing to updating the design and implementation of control and prevention strategies.