The news was terrifying to the colonialists of Massachusetts.
Smallpox had made it to Boston and was spreading very rapidly. The first
victims, who were passengers on a ship from the Caribbean, were locked up in a
house identified only by a red flag that reads “God have mercy on this house.” Meanwhile, hundreds of residents of
the busy colonial town had started to run for their lives. Many were terrified
of what might happen if they were exposed to the deadly virus.
They had every reason to fear. The virus was extremely
contagious and was spreading like wildfire in large epidemics. Smallpox
patients experienced fever, fatigue, and a crusty rash that could leave
disfiguring scars on the body. In up to 30 percent of cases, the virus killed
But the smallpox epidemic of 1721 was different from any that
came before it. The sickness swept through the city, killing hundreds. This was
a period before modern medical treatment or a robust understanding of the infectious disease. But an enslaved man known only as Onesimus suggested a
potential way to keep people from getting sick. Fascinated by Onesimus’ idea, a
brave doctor and an outspoken minister carried out a bold experiment to try to
stop the deadly smallpox.
Smallpox was one of that era’s deadliest diseases. Historian
Susan Pryor notes that “Few diseases at
this time were as universal or fatal.”
The European colonialists saw effects of smallpox not just among
their own countrymen, but among the Native Americans to whom they introduced
the disease. Smallpox destroyed Native American communities. And with no
immunity, they were unable to fight off the virus. Today, the death toll
of the native of Americans due to smallpox has been fingered as a deliberate
attempt by colonialists to decimate them.
The Smallpox virus also entered the town through slave ships.
Sometimes it was transmitted by African slaves who were packed in unsanitary
quarters. The infected among them passed the disease along to one another and,
eventually, to colonialists and inhabitants at their destinations. One of those
destinations was Massachusetts, which was then a center of the early slave
trade, in America. The first slaves were known to arrive in Massachusetts in
1638, and by the year 1700, about 1,000 slaves lived in the colony, most in
In 1706, an enslaved West African man was purchased for Cotton
Mather, who was a prominent Puritan minister. Cotton Mather gave the slave the
name Onesimus, after a Biblical slave whose name meant “useful.” Mather, who was a powerful figure in the Salem Witch Trials, believed that slave
owners had a religious duty to convert slaves to Christianity and also educate
them. But like other white men of his generation, he looked down on what he
called the “Devilish rites” of Africans and was worried that the slaves might
Cotton Mather didn’t trust his slave Onesimus. He wrote about
having to monitor him carefully due to what he thought was his “thievish”
behavior. He also recorded in his diary that he was a “wicked” and “useless”
slave. But in 1716, all that bad blood towards Onesimus would change when he told
Cotton something he did believe: That he knew how to prevent the smallpox
Onesimus, who “is a
pretty intelligent fellow,” Cotton Mather later wrote, told him he had had
smallpox—and then later didn’t. Onesimus told Cotton that he “had undergone 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 contagion.”
The operation Onesimus referred to involved rubbing the pus
from an infected person into an open wound on the arm of a non-infected person.
Once the infected pus was introduced into the body, the person who underwent
the procedure was automatically inoculated against smallpox. This procedure
wasn’t necessarily a vaccination, which involves exposure to a less dangerous
virus to provoke immunity. But it did trigger the recipient’s immune response
and protected the people against the disease most of the time.
Cotton Mather was fascinated at the efficacy of Onesimus’s
remedy. He soon verified Onesimus’ story with that of other African slaves and
also learned that the practice had been used in Turkey and China. He then
became an evangelist for inoculation which was also known as variolation, and then
spread the good news throughout Massachusetts and other places, hoping it would
help prevent the deadly smallpox.
But Cotton Mather hadn’t bargained on how unpopular the treatment
procedure would be. The same discrimination that caused him to distrust his
servant made other white colonists reluctant to undergo a medical procedure
developed by or for black people. Cotton Mather “was vilified,” historian Ted Widmer once told WGBH. He said that “A local newspaper, called The New England Courant, ridiculed him. An
explosive device was thrown through his windows with an angry note. There was
an ugly racial element to the anger.”
Religion also contributed to the refusal of the treatment by
the colonialists. Other preachers argued that it was against the will of God to
expose his creatures to such dangerous diseases.
But in 1721, Mather and Zabdiel Boylston got their chance to
test the power of inoculation. Bolyston was the only physician in Boston who
supported the technique.
That year, a smallpox epidemic spread from a ship to the
population of Boston, infecting about half of the city’s residents. Boylston
sprang into action, inoculating his son and his slaves against the smallpox disease.
Then, he began inoculating other willing people in Boston. Of the 242 people he
inoculated, only six died—one in 40. But among those who refused to take the
treatment, one in seven died.
The smallpox epidemic killed 844 people in Boston. This was
over 14 percent of the population of the city. But the treatment and the
results of that epidemic had yielded hope for future epidemics. It also helped
set the stage for vaccination against viruses. In 1796, Edward Jenner created
an effective vaccine that used cowpox to provoke smallpox immunity. Interestingly,
it worked. Eventually, smallpox vaccination then became mandatory in
Did Onesimus live to see the success of the technique he
introduced to Cotton Mather? Well, that isn’t clear to history. Nothing is really
known of his later life other than that he partially purchased his freedom from
Cotton Mather. To do so, he gave Mather money to purchase another slave.
What is clear to historians is that the knowledge he passed
on saved hundreds of lives—and led to the eventual eradication of smallpox.
In 1980, the World Health Organization declared smallpox
entirely eradicated from the world due to the spread of immunization worldwide.
It remains the only infectious disease to have been entirely wiped out of the surface
of the earth.
Onesimus’s instincts and knowledge of medicine points to the
historical facts that Africans invented medicine and are that they have been
exposed to science through their indigenous cultures and religions.
Americans and indeed the world needs to recognize the medical
contributions of men such as Onesimus, although it is no surprise that his name
has been swept under the rug, with the system giving credit to those that
learned from him.