Deadly Epidemic Swept Across Mexico, Killing Native Populations

In the sixteenth century, the worst epidemic in human history hit. It traveled to Mexico, possibly from Europe, and killed most of the native population.

The epidemic was a form of the salmonella virus, but what caused this deadly epidemic is not clear.

The first piece of evidence came from Hannes Schroeder, an ancient DNA researcher at the Natural History Museum of Denmark. She found a virus from the 1540s that killed 80 percent of Mexico’s inhabitants. The DNA was recovered from a stomach bacteria that was linked to this epidemic.

In 1519 when the outbreak occurred, Mexico’s population was at 25 million people. One hundred years later, the population was down to one million. One of the largest causes of this population decline was the cocoliztli outbreak, which killed seven to 18 million people between 1545 and 1576. After the outbreak, a Franciscan historian said, “In the cities and large towns, big ditches were dug, and from morning to sunset the priests did nothing else but carry the dead bodies and throw them in ditches.” Researchers at the National Autonomous University of Mexico in 2002 believe that viral hemorrhagic fever was the major cause of cocoliztli.

DNA remains from the sixteenth century were found and turned out to be Salmonella Paratyphi C. This disease existed 300 years prior to reaching Mexico. Spaniards might have infected the native people, which may have caused it to spread further. This virus spreads through fecal material, and in Mexico there weren’t good sanitary conditions, so it was able to spread fast and easily.

New evidence of the huge outbreak is still being found specifically about where it came from. Paratyphi C still infects people today. It kills 10-15 percent of the people that it infects if they are not helped. But Johannes Krause, an evolutionary geneticist, has a blueprint to figure out what’s behind the outbreaks.