Ecologist: Smallpox, one of the worst diseases ever to afflict humans, has in some outbreaks killed as much as 50 percent of local populations  The last known surviving cultures of variola -- the smallpox virus -- are confined to two high-security laboratories  Some scientists are anxious to destroy the remaining variola cultures, to which humans are susceptible
Research on the cultures, however, may someday lead to important benefits for humans, and so the cultures should not be destroyed
It is likely that the virus, if released, will develop a resistance to vaccines previously used to control it.