The Cocoliztli Epidemic Devastates Mexico

In 1545, a catastrophic contagion swept across the highlands of New Spain, initiating one of the deadliest demographic disasters in recorded history. Known to the native Nahuas as cocoliztli, meaning pestilence, the disease struck an Indigenous populace already deeply disrupted by the Spanish conquest and the fall of Tenochtitlan two decades earlier. Descriptions of cocoliztli, most fully recorded by the physician Francisco Hernández during a later outbreak in 1576, portray an extremely virulent disease. Sufferers experienced searing fevers, acute headaches, vertigo, dark urine, black tongues, and severe internal distress. Most terrifyingly, patients suffered profuse bleeding from the nose, mouth, and eyes, frequently dying within three or four days of the first symptoms.

The 1545 outbreak lasted until 1548, devastating communities across central and southern Mexico, and possibly reaching as far south as Guatemala. Contemporary observers struggled to grasp the scale of the destruction. Spanish encomendero Gonzalo de Ortiz wrote that the sickness carried off three of every four native people, while the friar Motolinia reported death rates of 60 to 90 percent among Native people. Modern estimates put the death toll across New Spain at 5 million to 15 million people, as much as 80 percent of the Indigenous population of Mexico. Mortality fell overwhelmingly on Indigenous communities, while Spaniards appeared to suffer far less.