Onesimus: The Slave Who Brought Inoculation To America And Saved The Country

By | October 10, 2019

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Otis Historical Archives of “National Museum of Health & Medicine” (via Flickr)

Smallpox was a singularly devastating disease in the 18th century, killing up to 30% of those infected within mere days or weeks of contamination. The virus was unique to other epidemics, at least in how people understood the disease. It was obviously spread from person to person without any needed carrier, as in the case of rats and the bubonic plague. It took down every kind of person, "both male and female, both old and young, both strong and weak, both white and black." It was responsible for reducing the Native American population by over 50% in the centuries after European contact. Initially, there was little to be done about the killer disease. Their best guess at treatment was bloodletting, which was kind of the duct tape of 18th-century medicine, so usually, they were resigned to managing symptoms.

There was one long-practiced medical tradition that actually seemed to work, but the problem was getting people to agree to it. While inoculation was common knowledge in most of the Middle East and parts of Asia prior to the 18th century, it was largely written off in America. It was practiced almost exclusively by enslaved men and women whose credibility within the Western medical community was about what you'd expect it to be. Just to recap: bloodletting=good, vaccines=dumb.

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Mezzotint portrait of Cotton Mather by Peter Pelham.

That would change in 1721 when a particularly horrific outbreak of smallpox occurred in Boston, Massachusetts. Cotton Mather, an acclaimed man of science who was already somewhat famous for his involvement in the Salem Witch Trials, just so happened to be living there, along with a West African man by the name of Onesimus who was enslaved to Mather. It was he who explained the concept of inoculation to Mather. As Mather wrote in a letter to John Woodward:

"[I asked] whether [Onesimus] ever had Small-Pox; he answered, both, Yes, and, No; and then told me, that he had undergone an Operation, which had given him something of Small-Pox, & would forever preserve him from it ... He described the Operation to me, and shew'd me in his Arm Scar, which it had left upon him; and his Description of it, made it the same, that afterwards I found related unto you by your Timonius."

What is now an accepted practice in the Western medical community caused quite a controversy when Mather began using the technique and proposing it to others. Newspapers like The New England Courant posted letters to the editor from people on both sides of the issue. Anti-inoculators wrote about their vehement distrust of the method, calling into question the logic of infecting an otherwise-healthy body with the disease, no matter how minor the resulting outbreak. They accused doctors of covering up deaths related to the inoculations, one claiming that a doctor "in his Letter to the Royal Society, owns that he saw Two die that were Inoculated; but at the same Time would fain insinuate that they died of some other Distemper."