Have Researchers Discovered What Caused the 16th Century Mexican Epidemic That Killed Over 80% of the Population?

A pair of recently published studies point the finger at a deadly form of salmonella as the cause of millions of deaths in a 16th century Mexican epidemic outbreak. This cocoliztli (pestilence in Nahuatl) occurred from 1545-1576 and took the lives of between 7 and 18 million people – leading some researchers to draw parallels with the Black Death that struck Eurasia in the 14th century.

The journal Nature reports that the native population of Mexico was around 25 million when Hernando Cortés arrived in 1519, but just a century later there were only 1 million people remaining. The primary cause for this dramatic decrease in population was apparently two major outbreaks of cocoliztli, one in 1545 and the other in 1576. As Dr. Acuna-Soto, a professor of epidemiology on the Faculty of Medicine at the National Autonomous University (UNAM) of Mexico wrote “In absolute and relative terms the 1545 epidemic was one of the worst demographic catastrophes in human history, approaching even the Black Death of bubonic plague.”

The 16th-century population collapse in Mexico, based on estimates of Cook and Simpson. (1948) (Public Domain)