Smallpox spreads 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. The virus can stay alive between 6 and 24 hours.
People were once vaccinated against this disease. However, the disease has been mostly wiped out.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 spread as part of a terrorism attack. The virus could be spread in spray (aerosal) form.