Tuberculosis in the New World:

In the past it has been strongly believed that tuberculosis was not present in the New World prior to 1492. Due to the devastating effects the disease had on the native population it was assumed that the Europeans must have carried it with them from the Old World (Pfeiffer 1991, Prat & Mendonca de Souza 2003).

Evidence of tuberculosis in humans has been traced back 5,000 years to Egypt. According to Pfeiffer (1991) if this is the origin of M tuberculosis it is much too late for the disease to have migrated to the New World via the Bering Land Bridge. On the other hand, Buikstra (1981) has suggested that New World tuberculosis may have been caused by, "a pathogen that is no longer in existence either due to its own extinction or its evolution into an entity which does not now cause acute infection in man.” Nevertheless, before any concrete conclusions can be made regarding the origins of tuberculosis in the New World Prat and Mendonca de Souza (2003) warn that, “factors like different pathogenic strains of the bacteria, the absence of long or permanent immunity and, of course, the socio-cultural determinants for the emergence of the disease have to be carefully considered.”

According to Prat and Mendonca de Souza (2003), “either the ancient prehistoric hunters brought the pathogens from Asian/European stocks and kept the infection at low endemic levels, or the pathogens were acquired directly from environmental reservoirs in America.” If the origins of Old World tuberculosis truly originated 5,000 years ago in Egypt then, as stated earlier, this is far too late for it to have come across the Bering Land Bridge.

The archaeological record has proven that there were in fact multiple migrations into the New World (Prat & Mendonca de Souza 2003). In fact, the current model accepted by most according to Neves et al., as noted by Prat and Mendonca de Souza (2003) is that non-mongoloid and mongoloid groups of Homo sapiens migrated into the New World in several waves 20,000 to 15,000 years ago. In fact, the ancestors of the modern Eskimo are not believed to have arrived in America until as recently as 6,000 years ago (Prat & Mendonca de Souza 2003).

Assuming then that tuberculosis existed in the New World prior to colonization Clark et al. (1987) proposed four possible theories regarding the emergence of TB in America. They are as follows, 1) “was caused by the exposure of human populations previously immunized by free Mycobacterium to M. tuberculosis,” 2) “was caused by less virulent variations of M. tuberculosis,” 3) “was caused by M. bovis acquired from wild fauna like the bison,” and 4) “was caused by different varieties of free Mycobacterium and this also would explain the high susceptibility to the European varieties of bacteria.”