probably passed on by itinerant practitioners and simple word of mouth. By the early 1700s smallpox inoculation, known as variolation, had spread to parts of Africa, India and the Ottoman Empire. It was in the latter that Lady Mary Wortley Montagu encountered it in 1717, when she witnessed local peasant women performing inoculations at seasonal ‘smallpox parties’. On returning to Britain, she had her children inoculated during an outbreak in 1721.

Mather, Onesimus and the epidemic in Boston

That same year, across the Atlantic, Boston was also struck by smallpox. Cotton Mather, a leading churchman, had previously been told about inoculation by Onesimus - his enslaved African worker - who had received the treatment as a child. The inoculation procedure was already practised in Africa. Inspired by Onesimus’s knowledge, Mathercampaigned for inoculation in the face of the growing epidemic, a call that met with some success and much hostility. But the actions of Lady Montagu, Onesimus and Cotton Mather ultimately hastened this knowledge transfer to the West.

Jenner and vaccination

Edward Jenner, an English country doctor and keen inoculator, later adapted the practice, developing a safer, more effective technique he called vaccination. Having noted that local people who caught cowpox gained immunity from the far more dangerous smallpox, he successfully induced such immunity in an experiment on a local boy, James Phipps, in 1796.

The slow decline of smallpox

Jenner’s adaptation of an ancient technique was the early herald for a series of other vaccines developed in the following two centuries. Made compulsory in 1853, smallpox vaccination anticipated the culture of