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History of Smallpox

Smallpox virus, artificially colored transmission electron microscope image. Copyright Dennis Kunkel Microscopy, Inc.The history of smallpox holds a unique place in medicine. One of the deadliest diseases known to humans, it is also the only human disease to have been eradicated by vaccination.

Symptoms of a typical smallpox infection began with a fever and lethargy about two weeks after exposure to the Variola virus. Headache, sore throat, and vomiting were common as well. In a few days, a raised rash appeared on the face and body, and sores formed inside the mouth, throat, and nose. Fluid-filled pustules would develop and expand, in some cases joining together and covering large areas of skin. In about the third week of illness, scabs formed and separated from the skin.

About 30% of cases ended in death, typically in the second week of infection. Most survivors had some degree of permanent scarring, which could be extensive. Other deformities could result, such as loss of lip, nose, and ear tissue. Blindness could occur as a result of corneal scarring.

Smallpox was spread by close contact with the sores or respiratory droplets of an infected person. Contaminated bedding or clothing could also spread the disease. A patient remained infectious until the last scab separated from the skin.

Smallpox plagued human populations for thousands of years. Researchers who examined the mummy of Egyptian pharaoh Ramses V (died 1157 BCE) observed scarring similar to that from smallpox on his remains. Ancient Sanskrit medical texts, dating from about 1500 BCE, describe a smallpox-like illness. Smallpox was likely present in Europe by about 300 CE.

Some estimates indicate that 20th-century worldwide deaths from smallpox numbered more than 300 million. The last known case of wild smallpox occurred in Somalia in 1977.


Bibliography for the Smallpox Timeline