Scientists believe they may have discovered the cause of an epidemic that struck Mexico’s Aztec population in 1545, killing up to 15 million people.

In a paper published in Nature Ecology & Evolution, they describe how DNA extracted from the teeth of 29 skeletons buried in a cemetery in southern Mexico revealed previously unidentified traces of the salmonella enterica bacterium.

The bacterium is known to cause enteric fever, of which typhoid is an example. According to the study, the symptoms tally with those mentioned in records from the time, which describe victims developing red spots on the skin, vomiting, and bleeding from various body orifices.

The epidemic was one of several to hit the indigenous population soon after the arrival of Europeans in the early 16^th century.

“When the Europeans arrived in Mexico, they brought with them lots of different diseases,” Ashild Vagene, co-author of the study, told The Independent. “There were dozens of epidemics across the New World and Mexico was particularly hard hit.”

“What we’re talking about is the devastating decimation of indigenous populations by previously unknown diseases,” Dr Caroline Dodds Pennock, lecturer in International History at the University of Sheffield, told The Independent.

“Mortality rates were maybe 80 or 90 per cent by 1600,” she said. “Imagine nine out of every 10 people dying – it’s almost unimaginable.”

The cause of the 1545-1550 epidemic has been debated for more than a century. Measles, pneumonic plague and influenza have all been suggested as possibilities, but historians have never reached a consensus.

More at the link.