Seals, sea lions likely spread tuberculosis to humans

WASHINGTON, Aug. 20 (UPI) -- It's widely agreed that seals and sea lions are adorable. But they're also deadly -- sort of.

Tuberculosis is not adorable; it kills between one and two million people every year. And new research suggests that the furry sea mammals known for balancing beach balls on their nose likely played a key role in transporting tuberculosis from Africa to the Americas. In fairness, humans in Africa started the whole thing.

Researcher at Arizona State University and the University of Tubingen, in Germany, charted the evolution of the deadly disease by collecting and comparing genetic samples of the pathogen-infected specimens from throughout the world. Their analysis included modern as well as ancient samples, including 76 DNA samples from New World pre- and post-contact sites.

Their analysis proved that tuberculosis was affecting native South American populations more than 1,000 years before Europeans arrived on the continent. Which left the question: how did it get there? By comparing genome map of the human-evolved disease with animal strains, researchers were able to connect the dots.

"The connection to seals and sea lions is important to explain how a mammalian-adapted pathogen that evolved in Africa around 6,000 years ago could have reached Peru 5,000 years later," Johannes Krause, Tubingen researcher and co-author of the new tuberculosis study, said in a press release.

"Our results show unequivocal evidence of human infection caused by pinnipeds, sea lions and seals, in pre-Columbian South America," said Arizona State and co-author Anne Stone. "Within the past 2,500 years, the marine animals likely contracted the disease from an African host species and carried it across the ocean to coastal people in South America."

Jane Buikstra, an Arizona State professor that collaborated with the main researchers, says the new findings are important, as tuberculosis continues to rise around the world. "This study and further research will help us understand how the disease is transmitted and how the disease may evolve."

The study was published this week in the latest edition of the journal Nature.