For millennia, humanity has feared smallpox, one of the world's deadliest diseases that killed roughly 3 out of every 10 people it infected. One of the earliest documented cases was found on an Egyptian mummy around the third century B.C. Cultures in Asia, Africa, and Europe all contain historic accounts dating back centuries of people suffering from smallpox. Descriptions of high fevers, aches, and body-covering pustules abound in early medical literature. Survivors were often disfigured by scarring; some were blinded if the blisters had formed close to their eyes.
Medical pracitioners developed different ways to treat the disease, but a major medical breakthough at the end of the 18th century when Edward Jenner, an English country doctor, created the smallpox vaccine through scientific observation and a remedy that came to England from Turkey. (Find out why vaccines are so crucial.)
In 1716 Lady Mary Wortley Montagu arrived in Turkey with her husband Lord Montagu, the new British ambassador to Turkey. Two years earlier, she had survived a bout with smallpox but bore the scars left by the disease. Lady Montagu mastered the local language and befriended Turkish women, through whom she made an extraordinary discovery: Her new friends would deliberately infect themselves and their children with pus from smallpox sufferers. They then suffered a mild bout of the disease, after which they were left immune to its deadly effects.