The origins and precolonial epidemiology of tuberculosis in the Americas: can we figure them out?

Paleologic evidence of tuberculosis in the precolonial Americas is reviewed to cast light on its origins and subsequent epidemiology. The genus Mycobacterium is an ancient one, and M. tuberculosis may have differentiated 20,400 to 15,300 years ago. The Americas were peopled by migrants from Asia in two major migrations, one occurring more than 20,000 years ago and the other 12,000 to 11,000 years ago. Tuberculosis reached the Americas with these migrants, persisting at a low level of endemnicity in small, dispersed population groups. Beginning about 1500 years ago, an epidemic of tuberculosis began, probably in the Andean region of South America. It did not reach or subsided in time to leave highly susceptible indigenous American populations at the time of European colonization.