Diseases amongst the 1400-1500

The first historical emperor who transformed the local Kingdom of Cusco into the vast Inca Empire was Pachacuti (Pachacuti Inca Yupanqui), starting around 1438; he's credited with major expansion and building projects like Machu Picchu, though older traditions name Manco Cápac as the mythical founder of the Inca lineage in Cusco. 

In 1520, Spain inadvertently unleashed a devastating smallpox epidemic in the Americas, starting with the Aztec Empire (Mexico), a virus brought by Hernán Cortés's expedition, which wiped out millions due to the <indigenous population's lack of immunity???> severely weakening the Aztecs and playing a crucial role in their conquest by the Spanish, causing societal collapse, mass death (5-8 million in the first wave), and famine. 


• An African slave, part of Pánfilo de Narváez's Spanish expedition in 1520, carried the virus to Mexico????

• Smallpox wasn't new to Spain in the 1500s; it was endemic (regularly present) there and in Europe, affecting royalty like Queen Elizabeth I later, but its devastating impact in this era exploded in the Americas after Spanish contact, starting around 1518-1520 with Cortés's arrival, where it killed millions of Indigenous people lacking immunity, fundamentally aiding Spanish conquest by crippling Aztec society. 

Around the 1500s, smallpox was endemic in Africa, with West Africans practicing early inoculation (variolation) by rubbing pus from mild cases into skin cuts to induce immunity, a practice later brought to the Americas via the slave trade, where it helped combat the disease, though the virus itself devastated Indigenous populations who lacked immunity, causing mass death, notes.

Before the arrival of Europeans in the 1400s, the Aztec and Inca empires had endemic diseases like those affecting any large population, but the devastating epidemics that truly crippled them (smallpox, measles, influenza, salmonella) were introduced by the Spanish in the early 1500s, to which natives had no immunity, causing massive death tolls, social collapse, and paving the way for conquest by creating famine, fear, and weakened armies.