Jenner also knew about variolation and guessed that exposure to cowpox could be used to protect against smallpox. The basis for vaccination began in 1796 when the English doctor Edward Jenner noticed that milkmaids who had gotten cowpox were protected from smallpox. However, fewer people died from variolation than if they had acquired smallpox naturally. After variolation, people usually developed the symptoms associated with smallpox, such as fever and a rash.
During variolation, people who had never had smallpox were exposed to material from smallpox sores (pustules) by scratching the material into their arm or inhaling it through the nose. One of the first methods for controlling smallpox was variolation, a process named after the virus that causes smallpox (variola virus).
People who survived usually had scars, which were sometimes severe. On average, 3 out of every 10 people who got it died. 18 th Century-Explorers from Great Britain bring smallpox to Australia.17 th Century-European settlers bring smallpox to North America.16 th Century-European settlers and the African slave trade import smallpox into:.15 th Century-Portugal occupies part of western Africa, bringing smallpox.11 th Century-Crusades further spread smallpox in Europe.7 th Century-Arab expansion spreads smallpox into northern Africa, Spain, and Portugal.6 th Century-Increased trade with China and Korea brings smallpox to Japan.Expanding trade routes over the centuries also led to the spread of the disease.
Historians trace the global spread of smallpox to the growth of civilizations and exploration.
Early written descriptions also appeared in India in the 7 th century and in Asia Minor in the 10 th century. The earliest written description of a disease like smallpox appeared in China in the 4 th century CE (Common Era). The finding of smallpox-like rashes on Egyptian mummies suggests that smallpox has existed for at least 3,000 years.
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