Smallpox is a highly contagious disease caused by the variola virus, a member of the Orthopox virus family. It is one of the most devastating diseases known to humanity, with a mortality rate as high as 30%. In 1967, the World Health Organization embarked upon an intensified vaccination campaign to eliminate smallpox, which culminated in the successful eradication of the disease globally by 1980.
By the mid-1980s, there were only two known repositories of variola virus: the Institute of Virus Preparations in Russia, and the US CDC. The events in the US in September and October 2001 highlighted the risk that the variola virus might be used as an agent of bioterrorism. Governments around the world are taking precautionary measures to be ready to deal with a potential smallpox outbreak.