The story
In 1545, a devastating epidemic swept through central and southern Mexico, then the colony of New Spain. The Nahuatl word cocoliztli simply means "pestilence". Sufferers had high fevers, headaches and bleeding, and died within days. Indigenous communities were hit hardest. Contemporary accounts and later estimates suggest the 1545 to 1548 outbreak killed somewhere between 5 and 15 million people, perhaps half or more of the surviving Indigenous population. A second great cocoliztli in 1576 to 1580 killed perhaps 2 million more.
The conquest had already shattered Indigenous societies through war, smallpox and other diseases. Its cause is still debated. In 2018 scientists analyzing DNA from victims buried at Teposcolula-Yucundaa in Oaxaca found the bacterium Salmonella enterica Paratyphi C, which causes enteric fever, suggesting it was introduced from Europe. Others argue the symptoms fit a native hemorrhagic fever spread by rodents, perhaps triggered by severe drought followed by rain, which tree rings record. Several diseases may have struck at once.
Why it mattered
- Indigenous population collapse in Mexico deepened labor shortages that pushed Spain toward the repartimiento and African slavery.
- Colonial authorities moved survivors into new towns (congregaciones), reshaping settlement patterns across Mexico.
- Ancient DNA research on cocoliztli became a landmark in using genetics to identify historical epidemics.
Sources
- Possible cause of early colonial era Mexican epidemic identified University of Tubingen
- Salmonella enterica genomes from victims of a major sixteenth-century epidemic in Mexico Smithsonian Institution (Nature Ecology & Evolution)
- Megadrought and Megadeath in 16th Century Mexico Emerging Infectious Diseases (CDC)
Contested history
Consensus: Cocoliztli epidemics killed millions of Indigenous people in 16th-century Mexico, but the pathogen or pathogens responsible are debated.
- Possible cause of early colonial era Mexican epidemic identified University of Tubingen
- Salmonella enterica genomes from victims of a major sixteenth-century epidemic in Mexico Smithsonian Institution (Nature Ecology & Evolution)
- Megadrought and Megadeath in 16th Century Mexico Emerging Infectious Diseases (CDC)
- Megadrought and Megadeath in 16th Century Mexico Emerging Infectious Diseases (CDC)
Community notes
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