In the early 1700s, New England and other American colonies were being ravaged by smallpox. However, in 1721, an African slave who had been gifted to the Minister Cotton Mather, described the African practice of variolation to prevent smallpox epidemics. Onesimus suggested administering infectious material (like pus) from the blisters of smallpox patients to a healthy person through a cut in the skin. This was to be performed in a controlled manner and under the supervision of a physician. The method led to smallpox symptoms that were milder while still conferring future immunity.
While people still developed severe symptoms and even died from smallpox via variolation, those who died were in a much smaller proportion than those who acquired smallpox naturally. The practice was so effective that African slaves sold in Massachusetts at the time were deemed to be more valuable if they bore the scar of variolation. However, Bostonians rebelled against an idea that was not only foreign but African – one critic, an eminent doctor, attacked Mather for his “Negroish” thinking. However, Zabdiel Boylston, a physician who believed Cotton Mather and Onesimus about the effectiveness of variolation, inoculated his own son and the slaves in his possession, resulting in one in forty people dying from smallpox.
By the end of the epidemic, 14 percent of the population of Boston had died, and as such the practice became more accepted in the colonies facing smallpox epidemics. In 1796, the vaccine based on cowpox was developed by Edward Jenner. By the mid-1800s, variolation was discontinued in favor of immunization with cowpox given that immunization was safer and more effective than variolation.
Onesimus partially purchased his freedom, but still remained in the service of Cotton Mather. His contribution to the understanding of smallpox and its prevention continues today.
Contributed by Dr. Jacqueline Powell, Associate Professor of Physiology