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Definition
By Mayo Clinic staffSmallpox is a contagious, disfiguring and often deadly disease caused by the variola virus. Few other illnesses have had such a profound effect on human health and history. In the 20th century alone, an estimated 300 million people died of smallpox.
The initial signs and symptoms of smallpox, which appear about two weeks after infection, resemble those of the flu — fever, fatigue and headache. Later, severe pus-filled blisters appear on the skin that eventually leave deep, pitted scars. Once symptoms develop, there's no effective treatment for smallpox and no known cure.
Naturally occurring smallpox was finally eradicated worldwide by 1980 — the result of an unprecedented immunization campaign. But the virus didn't disappear entirely. Stocks of smallpox virus, set aside for research purposes, are officially stored in two high-security labs — one in the United States and one in Siberia. This has lead to concerns that smallpox someday may be used as a biological warfare agent.
Symptoms
