Definition of Smallpox:

Smallpox is a serious and contagious disease due to a virus.

Causes, incidence, and risk factors:

Smallpox was once found throughout the world, causing illness and death wherever it occurred. It mainly affected children and young adults. Family members often infected each other.

Smallpox spreads easily from one person to another from saliva droplets. It may also be spread from bed sheets and clothing. It is most contagious during the first week of the infection. It may continue to be contagious until the scabs from the rash fall off.

Researchers believe that the smallpox infection might be able to stay alive (under the right conditions) for as long as 24 hours. In unfavorable conditions, the virus may only remain alive for 6 hours.

People were once vaccinated against this disease. However, the United States stopped giving the smallpox vaccine in 1972. In 1980, the World Health Organization (WHO) recommended that all countries stop vaccinating for smallpox.

There are two forms of smallpox:

• Variola major is a serious illness that can be life threatening in people who have not been vaccinated
• Variola minor is a milder infection that rarely causes death

A massive program by the World Health Organization (WHO) wiped out all known smallpox viruses from the world in the 1970s, except for a few samples saved for government research. 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.

You are more likely to develop smallpox if you:

• Are a laboratory worker who handles the virus (rare)
• Are in a location where the virus was released as a biological weapon

It is unknown how long past vaccinations stay effective. People who received the vaccine many years ago may no longer be fully protected against the virus.

THE RISK OF TERRORISM

There is a concern that the smallpox virus could be intentionally spread through a terrorism attack. The virus could be deliberately spread in spray (aerosal) form.