Zoonotic TB

Zoonotic Tuberculosis (zTB) is not a new disease but has long been neglected. Majority of tuberculosis (TB) cases in humans are caused by Mycobacterium tuberculosis (M. tuberculosis). A number of other organisms from the  M. tuberculosis complex (MTBC), present in animals and the environment, can cause zoonotic TB (zTB), these include M. canetti, M. bovis, M. caprae, M. microti, M. pinnipedii, M. mungi, and M. orygis. 

Zoonotic TB affect the lungs, lymph nodes, and other parts of body. In many cases is clinically indistinguishable from TB caused by M. tuberculosis. However, as with M. tuberculosis, not everyone infected with M. bovis becomes sick. TB patients those who are infected but not sick are called as TB infection.

Burden of Zoonotic TB

Of 10 million people currently with new active TB worldwide, 140 000 (range, 69,800–235,000) are estimated to be new cases of zTB (1.4%) of which an approximately 11,400 (8.1%, range 4,470-21,600) died. However, zTB disease is largely underreported and, these wide ranges are indicative of major diagnostic challenges and poor public health surveillance and reporting structures in endemic countries. The highest numbers were reported from Africa (68,900) and Southeast Asia (43,400). South-East Asia comprises almost 44% of the global TB burden.

In India, Zoonotic TB continues to remain largely hidden. Evidence indicates that, a pooled prevalence of 7.3% (estimated 21.8 million) infected cattle in India. Although in India, there is no such prevalence available for humans, it has been estimated that M. bovis causes ~10% of the total human TB cases in developing countries.