In the early 1700s, about a century before Edward Jenner conceived the idea of a smallpox vaccine based on the cowpox virus, smallpox was ravaging New England and other American colonies.
Colonists in Massachusetts saw smallpox arrive with cargo ships to Boston repeatedly. There was not much the authorities could do other than impose quarantines and treat the sick.
This changed thanks to the wisdom passed on by Onesimus, an African man gifted into slavery to Cotton Mather, an influential church minister in Boston.
Mather held Onesimus in slavery since 1706, conversing with him, unsuccessfully attempting to convert Onesimus to Christianity and learning about his past.
In 1716, Mather asked Onesimus whether he had ever contracted smallpox. Onesimus described the process of variolation to prevent smallpox epidemics, a practice which was widely used in his home area back in West Africa.
Variolation consisted of first taking infectious material (like pus) from the blisters of smallpox patients.
A healthy person would then receive the material through a cut in the skin in a controlled manner and under the supervision of a physician.
Of course, the procedure was not without risk. People still developed severe symptoms and even died from smallpox via variolation, but those who died were much smaller in proportion than those who acquired it naturally from another person.
Benjamin Franklin, the founding father of the United States, reasoned with the public about the lessened risk from variolation compared to natural smallpox.
Mather followed Onesimus’s medical advice because “inferiority had not yet been indelibly stamped into the bodies of Africans.”
Additionally, Mather believed that disease, specifically smallpox, was a spiritual and physical punishment, so he saw the procedure as “God’s providential gift,” as well as a means of receiving recognition from New England society and reintroducing the influence of religious leaders in politics.
After doing some research, Mather found that variolation was practised in other parts of the world, not just Africa, notably China and Turkey.
The practice was so effective in conferring immunity that enslaved Africans sold in Massachusetts were considered more valuable if they bore the scar of variolation.
This research and correspondence with medical experts encouraged Mather to advocate for variolation in the colonies.
Needless to say, Mather’s proposal met resistance. According to an article appearing in the Boston Globe, “the people of Boston were terrified and angry…..fearing that inoculation might spread smallpox further.”
There was a racial overtone to their response, as they rebelled against an idea that was not only foreign but African with some of Mather’s opponents comparing inoculation to what we would today call terrorism.
In 1721, half of Boston’s residents were infected with smallpox, about 11,000 people.
Zabdiel Boylston, a physician who believed Mather and Onesimus on variolation, inoculated his own son and the enslaved people working in his household.
The result was that one in forty inoculated by Boylston died from smallpox. In those infected naturally, one in seven died, a risk ratio of 5.7 meaning that people who acquired the disease naturally were almost six times more likely to die than those who acquired it through variolation.
Based on this experiment with variolation, the practice became more accepted in colonies facing smallpox epidemics.
By 1796, Edward Jenner would develop a vaccine based on the cowpox virus. However, variolation was discontinued in the mid-1800s in favour of immunization with cowpox, as it was safer and more effective.
Little else is known of Onesimus other than that later he would partially purchase his freedom, but still remain in the service of Mather.
In 1980, the World Health Organisation declared that smallpox had been completely eradicated due to global immunisation efforts, making it the first and only human infectious disease for which this has been accomplished.
There is no doubt that the contribution that Onesimus made towards understanding smallpox and its prevention was invaluable and lives on today.
Unfortunately, he was born into a caste that was not allowed to profit from his wisdom, his genius, and even from his labour.
His life was stolen from him when he was shipped to America as a slave. The life-saving gift that he gave to America did not even earn him his freedom.
Instead, his genius conferred an immense fortune to some of what sometimes used to be known as the “idle rich” in America.