Story highlights A new technique allows ancient DNA to be studied with specific results

"Pestilence" cemetery contained salmonella bacteria, which likely caused typhoid fever

(CNN) In the 16th century, an epidemic known as "cocoliztli" that caused bleeding and vomiting swept through large areas of Guatemala, Mexico and even reached Peru. It wiped out 80% of the population, killing millions of people.

Ancient DNA and a new technique have been used to determine the likely cause of this mysterious epidemic that contributed to a "cataclysmic" population decline.

Salmonella genomes, which cause typhoid fever, were recovered from DNA within the teeth of 10 skeletons buried in an undisturbed "cocoliztli" or "pestilence" cemetery in Oaxaca, Mexico. This would be the first known occurrence of salmonella in the Americas, according to a new study published in the journal Nature on Monday. Typhoid fever has long been suspected due to the recorded symptoms, but this is the first identification of bacteria at the site.

The researchers also believe that the arrival of Europeans to what was then known as Mesoamerica caused the devastating epidemic. Europeans were susceptible to enteric fever, also known as typhoid fever, and it is very likely that they were carriers for the disease when they arrived to conquer Mesoamerica.

"The cocoliztli is a mysterious historical epidemic, and over the years many have speculated on its cause," said Kirsten Bos in an email, study author and group leader of molecular palaeopathology at the Max Planck Institute for the Science of Human History in Germany. "This is the first time that ancient DNA has been successful in identifying a candidate pathogen for it."

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