Sea lions may have been first to spread tuberculosis internationally

Sea lions have been found to be capable of transmitting tuberculosis to people, and may have been the first species to spread the disease internationally, according to a report from The Scientist.

Anne Stone of Arizona State University and her colleagues dated the transmission of tuberculosis from pinnipeds to people at around 700-1000 A.D., well before people would have experienced the spread of tuberculosis from a population of Europeans, as originally thought.

Unlike many other infectious diseases, where the marks of infection disappear with deterioration of infected flesh, the bodies of organisms infected with tuberculosis can retain characteristic imprints on their bones, which can still be recognized hundreds of years later. Using some old specimens and next-generation DNA sequencing techniques, Stone and the other researchers pinned the spread of tuberculosis on an ancient population of pinnipeds, not people.

Top image: Sea lion rests on a beach. (Credit: Kelly J. Kane, via Wikimedia Commons/CC BY 3.0)