During the Age of Exploration, Europeans traveled to the Americas to explore and trade. Along with goods, animals, and culture, they also brought diseases that had a devastating impact on Indigenous populations. Diseases such as smallpox, measles, and influenza were common in Europe and typically caused mild illnesses. But in the Americas, they were often deadly because Indigenous people had never been exposed to them and had no natural immunity. This type of outbreak is known as a virgin soil epidemic, where a disease spreads quickly in a population with no prior exposure.
Christopher Columbus’s voyages between 1492 and 1504 created direct contact between Europe and the Americas. His ships carried people, goods, and animals, including pigs and rats, which brought new diseases. In 1493, Columbus brought pigs from the Canary Islands to Hispaniola. These pigs likely spread swine flu, which caused an outbreak affecting both European colonizers and Indigenous communities. Diseases also spread through direct contact between explorers and Indigenous people. Since the Americas had few domesticated animals before European arrival, Indigenous populations had not developed immunity to the diseases animals carried, making the impact worse.
Historians believe disease caused one of the largest population losses in history. Though exact numbers are unknown, some researchers estimate that at least 80% of Indigenous people in the Americas died from disease after European contact. For example, census records show the Taíno population on Hispaniola fell from about 60,000 in 1508 to 23,000 by 1516. Smallpox may have arrived soon after, with a death rate around 50%, often wiping out entire communities. These diseases spread fast, especially among adults who had no childhood immunity. The population loss weakened resistance to colonization, making it easier for Europeans to conquer and settle the land.