Magazine article Natural History

Rewriting TB History

Magazine article Natural History

Rewriting TB History

Article excerpt

How and when the tuberculosis bacterium, Mycobacterium tuberculosis, arrived in the New World has been a matter of debate. Genetic data conflicts with archaeological evidence on whether the disease was introduced by the Spanish conquistadores in the 16th century or arrived on the continent long before them. A new study on bacterial DNA obtained from ancient Peruvian skeletons provides evidence for the latter and proposes a surprising route of transmission.

Analyses of M. tuberculosis's DNA show that current strains from the Americas are closely related to those in Europe, a result that supports the idea of a relatively recent European dissemination of TB. But studies of pre-Columbian microbial DNA, confirming archaeological analysis of skeletal material, found telltale clues of TB in thousandyear- old human remains. The evidence, however, has been only preliminary and offered no information about the bacterium's route of entry or its relationship to modern forms of the disease. In a new paper, Kirsten I. Bos of the University of Tübingen in Germany and an international team of researchers examined sixtyeight skeletal samples from New World sites, pre- and post-European contact.

The team first isolated M. tuberculosis's DNA from their samples. "It's a technique that works just like a fishing expedition, where you create a molecular bait that will match the target molecule of interest," explains Bos. Thus, they identified three well-preserved samples of M. …

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