Smallpox

Smallpox, acute, highly contagious viral disease, often fatal, that appears to have been completely eradicated. After a 12-day incubation period, the first phase was marked by high fever, prostration, and toxicity, followed three or four days later by a rash, characteristically on the face, the palms, and the soles of the feet. During the next six to ten days the rash developed into pustular pimples. The return of the fever and toxicity initiate the second stage of disease, during which the pustules could become secondarily infected by bacteria. As recovery began, the pustules became crusted, often leaving scars, and the fever and toxicity subsided. Death was caused by infection of the lungs, heart, or brain. A person with smallpox was infectious from about the third day through the erupting phase.

In 1967 the UN World Health Organization (WHO) launched a worldwide vaccination campaign against smallpox; at the time, some 10 to 15 million cases of the disease occurred each year, with more than 2 million deaths. By mid-1975, when all India was declared free of smallpox, only a few cases were left in two countries, Bangladesh and Ethiopia. In 1979, after two years without a reported case of smallpox, the WHO marked the disappearance of smallpox from the Earth. It recommended that countries stop vaccinating against the disease and that laboratory stocks of the virus be destroyed. Underlining the importance of this last request was the death of an English woman in 1978 of smallpox contracted from a laboratory working with the virus. Currently, stocks of smallpox virus are known to exist only in the United States and Russia.