Smallpox is a deadly infectious disease caused by a virus. It hasn’t caused an infection in the wild since the 1970s. No one has had smallpox in the United States since 1949. The last death from smallpox was in the United Kingdom in 1978. Though you’re not likely to encounter smallpox in the wild, it still exists in two labs.

Despite the hardiness of the variola virus, smallpox was not a highly infectious disease; infected persons usually did not infect more than two to five of their closest contacts.

Smallpox is an acute infectious disease caused by the variola virus. The last naturally acquired case of smallpox occurred in 1977. Smallpox was declared eradicated from the earth in 1980. However, the events of September and October 2001 have emphasized the need to be prepared for a biologic attack using smallpox as a weapon.