Onesimus: The First Stage to Eradicate Smallpox

Terrifying news had reached Boston: the infectious, debilitating disease Smallpox had reached the colonial town and was spreading rapidly. Its first victims, passengers on a ship from the Caribbean, were shut up in a house identified only by a red flag that read “God have mercy on this house.” Hundreds of Bostonians began flee for their lives.

The 1721 epidemic wiped out over 14 percent of Boston’s population.

As death took over the city, an enslaved West African known only as Onesimus suggested a potential way to keep people from getting sick. He described a process of rubbing pus from an infected person into an open wound on the arm. Once the infected substance was introduced into the body, the person who underwent the procedure was inoculated against the disease.

What Onesimus proposed what not a vaccination, but it did trigger the recipient’s immune response and protected against the disease most of the time. Intrigued by Onesimus’ idea, a Puritan minister named Cotton Mather who purchased him and a doctor named Zabdiel Boylston undertook a bold experiment to try and stop smallpox in its tracks.

Years prior though, Mather didn’t trust Onesimus, having described his behavior as “thievish,” and calling him “wicked” and “useless.” He looked down on what he called the “Devilish rites” of Africans and worried that enslaved people might learn to rebel. But after Onesimus shared with him an approach to the disease, Mather then considered Onesimus “a pretty intelligent fellow.”

Onesimus admitted that he had had smallpox, and then didn’t. He “had an operation, which had given him something of the smallpox and would forever preserve him from it…and whoever had the courage to use it was forever free of the fear of it.”

Fascinated, Mather spoke with other slaves about this procedure, a practice he then learned, had been used successfully in Turkey and China. With the hopes that the process would further prevent smallpox, Mather began to spread the news throughout Massachusetts but had no idea how unpopular the idea would be. Mather soon felt the wrath of his fellow white Americans.

The same prejudices that caused Mather to distrust Onesimus made the white colonists reluctant to undergo a medical procedure developed by a black man. He was ridiculed, threatened and shunned by other preachers. But in 1721, when the smallpox epidemic took over Boston, Mather and Boylston got their chance to test the power of inoculation.

Boylston inoculated his son, his slaves and other residents in Boston. Of the 242 people inoculated, only six died. One in 40, as opposed to one in seven deaths among the population of Boston who didn’t undergo the procedure.

Whether Onesimus lived to witness the success of the technique he introduced to Mather is unknown. The details of his later life, other than the fact he partially purchased his freedom, are unclear. What is clear is that the knowledge he passed on saved hundreds of lives, and led to the eventual eradication of smallpox worldwide.