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From: http://www.nlm.nih.gov/m ... /001356.htm

Smallpox

Alternative Names
Variola - major and minor; Variola

Definition Return to top

Smallpox is a viral disease characterized by a skin rash and a high death rate.

Causes Return to top

Smallpox was once found throughout the world, causing illness and death wherever it occurred. Smallpox was primarily a disease of children and young adults, with family members often infecting each other.

There are two forms of smallpox:

* Variola major is a serious illness with a death rate of about 30% or more in unvaccinated people
* Variola minor is a milder infection with a death rate of less than 1%.

The incubation period for smallpox is approximately 12-14 days.

A massive program by the World Health Organization (WHO) eradicated all known smallpox viruses from the world in 1977, except for samples that were saved by various governments for research purposes. The vaccine was discontinued in the United States in 1972. In 1980, WHO recommended that all countries stop vaccinating for smallpox.

In 1980, WHO also recommended that the remaining virus samples be transferred to two WHO laboratories for storage. Those laboratories were the Centers for Disease Control (CDC) in Atlanta, Georgia, and a laboratory in Russia. Russia, however, started a program to produce the smallpox virus in mass quantities, specifically for bombs and other weaponry.

Some believe that other countries such as Iraq, Iran, and North Korea may also hold some stores of the smallpox virus. Researchers continue to debate whether or not to kill the last remaining samples of the virus, or to preserve it in case there may be some future reason to study it.

According to the CDC, since the vaccine has not been administered in the U.S. since 1972, those persons who had received the vaccine in the past are likely susceptible now (as are those who have never been vaccinated). It is not known how long previous vaccinations would remain effective, but it is unlikely that people would still have a high enough level of immunity to protect against the virus.

Risk factors for smallpox include being a laboratory worker who handles the virus (rare), or being in the environment where the virus was released as a biological weapon.

THE RISK OF TERRORISM