West African Variolation Knowledge Transmitted to the Americas via Onesimus
- Date
- 1721 (knowledge conveyed c. 1716; campaign 1721-1722)
- Category
- Science, technology & invention
- Region
- Boston, Massachusetts Bay Colony (British North America)
- Era
- Early Modern
- Significance
Onesimus, a West African man (likely of Akan/Coromantee origin from the region of modern Ghana) enslaved in Boston in the household of Puritan minister Cotton Mather, described around 1716 a longstanding African practice of inoculation against smallpox, telling Mather that people would take matter from a smallpox sore, cut the skin, and introduce a drop to confer lifelong immunity; he showed Mather a scar from his own procedure.
This variolation technique had been practiced for generations across sub-Saharan Africa, the Middle East, and Asia but was largely unknown in the British American colonies. When a severe smallpox epidemic struck Boston in 1721, infecting roughly 5,759 of about 10,600 residents and killing about 844 (a natural-case fatality rate near 15 percent), Mather drew on Onesimus's account to urge the city's physicians to attempt inoculation. Only Zabdiel Boylston agreed, and he inoculated about 247 people, of whom only 6 died (roughly 2 percent), a dramatically lower mortality than among those who contracted the disease naturally. This episode marked the first organised use of inoculation in the Thirteen Colonies and helped lay the empirical groundwork for later vaccination, even as the African source of the knowledge was long minimised.
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Empires active in 1721 (knowledge conveyed c. 1716; campaign 1721-1722)
- Spanish Empire1492 CE – 1976 CE
- Portuguese Empire1415 CE – 1999 CE
- Mughal Empire1526 CE – 1857 CE
- Qing Dynasty1636 CE – 1912 CE
- British Empire1583 CE – 1997 CE
- Russian Empire1721 CE – 1917 CE
Related science, technology & invention events
- Newton's Principia and universal gravitation1687
- Watt patents the rotative steam engine1781
- Edward Jenner Develops Smallpox Vaccination14 May 1796
- Variolation against smallpox reaches Europe1721
- Sawai Jai Singh II builds the Jantar Mantar observatoriesc. 1724
- Arkwright's Cromford Mill and the birth of the factory system1771 (water frame patented 1769)
Further reading
The wider story
A Little History of Science
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