what is the pathogen category for smallpox
Background. Smallpox is an acute, contagious disease caused by the variola virus, a member of the genus Orthopoxvirus, in the Poxviridae family (see the image below).Virologists have speculated that it evolved from an African rodent poxvirus 10 millennia ago.See Etiology.) Cowpox virus scarification by Jenner, used to induce protective immunity against smallpox, is not a single species but a group of up to 5 virus species that infects cows, humans, and other animals.