Bovine Tuberculosis in the Wolaita Zone of Ethiopia

This study explores livestock health, focussed on bovine tuberculosis (BTB), in Wolaita, Ethiopia, through participatory abattoir appraisals, observational analyses, and molecular investigations. The research explored three areas: (i) assessing physical abattoir facilities and the prevalence and characterization of post-mortem lesions for evidence of bovine tuberculosis, (ii) the potential economic implications of these findings, and (iii) molecular characterisation of the causative agents of suspect tuberculous lesions. Investigations into the infrastructure of public abattoirs revealed significant deficiencies, with substandard facilities impacting the quality of meat inspection services. Across surveyed abattoirs, 26.6% of slaughtered animals exhibited gross lesions, 65% of which posed potential public or animal health risks. Lesion prioritization indicated that mineralized/calcified lesions ranked highest (priority score: 0.67), followed by cystic lesions (0.58). Anatomical distribution analysis highlighted the lungs, mediastinal, and bronchial lymph nodes as primary sites of concern. Importantly, some lesions, such as those associated with BTB, represent significant zoonotic threats. The study emphasizes the urgent need to address infrastructural and procedural shortcomings in local abattoirs to safeguard public health. A separate component of the research assessed the prevalence of suspect tuberculous lesions in beef cattle and their associated economic impacts. Of 2,251 cattle examined between May 2020 and July 2021, 5.42% presented lesions indicative of tuberculosis. Lesions were classified as mild (53.3%), moderate (22.1%), or severe (24.6%), with the lungs (59%) and liver (36%) being the most affected organs. Lesion prevalence was significantly associated with factors such as age, breed, fattening system, and cattle source. The economic loss due to condemned edible offal totalled €656.95 during the study period, underscoring the financial burden on the local farming sector. Raising awareness among farmers, veterinarians, and public health officials about BTB is critical to mitigating these risks. To complement these findings, a molecular study investigated the causative agents of suspect tuberculous lesions in cattle. From 122 animals with suspect lesions, 180 tissue samples underwent bacteriological culture and genetic analysis i.e., LAMP, end-point PCR, and whole genome sequencing. Results identified Mycobacterium bovis in four carcasses and Mycobacterium tuberculosis in one, confirmed through whole genome sequencing (WGS). These isolates displayed genetic similarity to known Mycobacterium tuberculosis complex (MTBC) lineages in Ethiopia. The presence of M. tuberculosis in cattle raises concerns about human-to-animal transmission. The study provides valuable genomic data for Ethiopian MTBC isolates, advancing the understanding of BTB and its public health implications. In conclusion, this research highlights the many challenges posed by detection, characterisation and potential impact of lesions in slaughtered cattle, including public health risks, economic losses, and zoonotic threats. Addressing these issues requires enhanced abattoir infrastructure, targeted awareness campaigns, and continued research into mycobacterial transmission dynamics to protect both livestock and human populations.