Smallpox is a contagious, disfiguring and deadly disease caused by the variola virus. Experts believe that smallpox over the centuries has killed more people than other infectious diseases. The last naturally occurring case of smallpox was reported in 1977.In 1980, the World Health Organization declared that smallpox had been eradicated. There's no treatment or cure for smallpox. The only prevention is vaccination.
Attribution: Straight Talk Foundation