Seals the culprits for bringing TB to Americas

Tuberculosis likely spread from humans in Africa to seals and sea lions that brought the disease to South America.
Sara Marsteller/Arizona State University

Seals and sea lions, not Europeans as previously thought, took tuberculosis to the Americas, a group of researchers has found.

They analysed tuberculosis DNA recovered from three 1,000-year-old Peruvian skeletons, that does not match European strains of TB. Instead, it it closely resembles one that infects seals in the Southern Hemisphere.

The most likely scenario, researchers believe, is that seals and sea lions contracted the disease from a host animal from Africa, where the disease likely originated, and swam across the Atlantic where they were eaten by local people.

"The source of tuberculosis in the New World has long been a question for researchers," said Elizabeth Tran, biological anthropology program director of the US National Science Foundation which funded the study, published in Nature.

"This paper provides strong evidence that marine mammals may have been the likely culprits."

The research also shows that TB is much younger than we thought, probably evolving in Africa about 6,000 years ago.

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