Today, the average American is unlikely to spend time worrying about malaria. Although the disease is commonly perceived to be restricted to other parts of the world, it played a significant role in shaping American history. It even helped turn the tide of the American Revolutionary War by infecting so many British soldiers that General Cornwallis was forced to surrender at Yorktown.
First-year students in a 2019 introductory seminar class led by Erin Mordecai, an assistant professor of biology in the School of Humanities and Sciences (H&S), delved into this and other historical examples of how vector-borne diseases – those caused by infectious pathogens spread by living organisms or “vectors” – influenced human history. Throughout the course, they collaborated on a paper highlighting various trends in which these illnesses impacted historical societies. Their findings have now been published in the latest issue of the journal Ecology Letters.
“The mechanisms and consequences of vector-borne diseases are multimodal and far more pervasive than we had previously thought,” said Tejas Athni, a student in the seminar and first author of the paper.
As Athni and his fellow students conducted their research, they discovered recurring themes across societies throughout time. One theme was that diseases don’t affect all populations equally – a simple fact that had major ramifications throughout history. In the case of the American Revolution, many Americans had grown up in the South and were exposed to malaria young, allowing them to develop immunity. This granted them a strategic advantage over the less immune British army, which ended up being decimated by the disease.
A more sobering trend unearthed by the group’s investigations was that disease tended to prey on inequities in societies, leaving marginalized groups most at risk. Both intentionally and unintentionally, it was weaponized time and again to enforce unjust hierarchies of power. In the American South, for instance, enslaved Black people were often forced to work in conditions that left them exposed to mosquitoes and made them much more vulnerable to malaria. To make matters worse, this inequity was used by White people to encourage the racist belief at the time that Black Americans were morally inferior and to justify Jim Crow segregation laws in the South.
This study's co-authors include Lisa I. Couper, a 2018 SGF fellow, and Marissa Childs, a 2019 SIGF Fellow.