How did epidemic diseases affect Indigenous populations after the Spanish conquest?

Following the Spanish conquest, Indigenous populations across the Americas experienced a catastrophic demographic collapse primarily due to the introduction of Old World diseases. Before 1492, Indigenous peoples lacked exposure to, and therefore had no inherited immunity against, acute infectious diseases common in Eurasia and Africa, such as smallpox, measles, influenza, typhus, and whooping cough.12

These pathogens spread rapidly as epidemics, causing mortality rates that reached as high as 95 percent in some regions by 1650. In the Caribbean, the Indigenous population plummeted by more than 99 percent by 1600. This biological crisis was compounded by the physical and psychological stresses of the conquest, including mass violence, slave raids, famine, and forced labor systems like the encomienda.321

While some scholars emphasize the role of direct conflict, historical analysis indicates that the most significant factor in the shrinking of Indigenous populations was the unchecked spread of these introduced diseases. This profound loss of life remains a central, tragic element of the colonial era, reflecting the immense suffering endured by Indigenous peoples.13