1545–1576Reputable sourceDebated
Cocoliztli: The Great Dying of Mexico
On the timeline · around 1545–1576 · Plague and Pestilence
What happened
In 1545 a mysterious disease the Aztecs called cocoliztli ('pestilence') erupted in the highlands of Mexico, and struck again in 1576. Together the two epidemics killed an estimated 7 to 18 million people — a huge share of the surviving Indigenous population.
Why it matters
The cocoliztli epidemics were among the deadliest disease events in the Americas, compounding the smallpox catastrophe of the conquest and helping to depopulate central Mexico under Spanish rule.
How we know
The 1545 and 1576 death tolls come from colonial records; the cause is debated. A 2018 ancient-DNA study recovered Salmonella enterica (Paratyphi C) from victims' teeth, pointing to a form of enteric fever, while earlier researchers had proposed a viral haemorrhagic fever worsened by drought.
Sources
- National Geographic. Deadly Aztec Epidemic 'Cocoliztli' Linked to Salmonella · Reputable source
Related timelines
- The Aztec Empire → — Epidemics and the collapse of Indigenous Mexico