This is part of a student blog series as part of the University of Pittsburgh’s Disease Ecology Class that our own Shane M Hanlon is currently teaching. Find out more about the series and read all the posts here!  

By Kendrick Zuo

One of the most well-known infectious diseases that had existed throughout history is Smallpox. The Variola virus is the type of virus that is involved in causing this disease. Smallpox tends to spread easily between one individual to another, which makes this disease highly contagious. Fever, vomiting, rashes, body aches, and fluid-filled blisters that are covered with scabs are the kind of symptoms that usually occur among Smallpox infected individuals. The duration of the disease generally goes on for around four weeks. The mortality rate of Smallpox is typically about 30 percent. However, the mortality rate was at a much higher rate during historical times. The mortality rate was so high that it nearly wiped out many indigenous civilizations in the New World. 

The very first case of Smallpox that had caused a dramatic reduction in the local population in the New World was in Hispaniola, which is today known as Haiti and the Dominican Republic. The majority of the Tainos that resided in Hispaniola had succumbed to Smallpox since they lacked immunity after the Spaniards arrived in Hispaniola. However, the most notable event where Smallpox played a huge role in decimating a native population in the New World was in modern-day Central Mexico, where the Aztec Empire was primarily located. During the year 1519, the Spaniards started the process of conquering Mexico where the capital city of the Aztec Empire, Tenochtitlan, was laid into ruins a few years later. This circumstance has put an end to the Aztec Empire while Mexico then became known as New Spain by the Spaniards. One of the major factors that led to the downfall of the Aztec Empire was Smallpox. Through the conquest of Mexico in the year 1519, more than 30 million indigenous inhabitants lived in Mexico. Yet, due to Smallpox, the numbers had drastically declined to at most approximately 1.5-3 million individuals in just one hundred years later. With the Aztec Empire submitting rule into the hands of the Spaniards, the Spaniards had finally achieved their goal of conquering Mexico. The Aztec Empire was not the only major domain in the New World that was wrecked by Smallpox as the Incan Empire had also fallen victim to this infectious disease. As a result, just like the Aztec Empire, the Incan Empire had met its fate to the Spaniards as well. It has been said that Smallpox had managed to reach Mexico from Cuba and then spread deep down into Tenochtitlan in just under two years. Specifically, it all started with the Smallpox virus being brought into Mexico by a Spanish slave who had sailed on to Mexico through a Spanish ship from Cuba.   

Overall, in the New World, Smallpox had managed to claim around 40 to 50 million lives of the indigenous population. This shows that the Smallpox mortality rate during that particular event was around 90 percent. Now in modern times, Smallpox has been fully eradicated due to the creation of vaccines. Additionally, even if deaths do occur, the mortality rate is now only at 30%. The vaccine is the tool to help maintain and reduce the frequency of infectious diseases. If only vaccines were around in the Pre-Columbian Americas, the native population would not have been dramatically affected as much since they would have built resistance against Smallpox. Therefore, the lives in the New Worlds could have been so much different even through the present day, especially when it comes to the Amerindian population size.

Sources:

https://www.cdc.gov/smallpox/index.html

Smallpox and the Conquest of Mexico