Animals as overlooked victims and vectors of tuberculosis: review of Mycobacterium tuberculosis and Mycobacterium bovis

Abstract Tuberculosis (TB) is the world′s leading infectious disease in humans usually caused by Mycobacterium tuberculosis (Mtb). However, Mycobacterium bovis can also lead to TB in humans and is the most common TB-causing bacteria in animals. Roughly 140,000 people fall sick from M. bovis every year, and tens of millions of animals are estimated to have TB infection, but there are major barriers to diagnosis and treatment in both humans and animals. For example, most standard TB tests do not detect M. bovis . M. bovis is also naturally resistant to pyrazinamide, a first-line TB drug, and livestock, wildlife, and zoo animals can function as TB reservoirs, infecting new people in otherwise TB-free settings. Effective control measures and integrated strategies targeting Mtb, M. bovis , and other TB-causing bacteria across human, animal, and environmental domains are essential to significantly reduce transmission and achieve global objectives such as the World Health Organization′s END TB Strategy. This review therefore takes a "One Health" approach, which focuses on three pillars and the connections between them: human health, animal health, and the health of their shared environment. One Health is a helpful framework for understanding complex threats like TB because it reflects the importance and interconnectedness of all three priorities, and can inspire solutions that are adaptive, interdisciplinary, and sustainable.