Epidemiological implications of the typing of variola isolates.
D000349:Africa; D000818:Animals; D001208:Asia; D002642:Chick Embryo; D000882:Haplorhini; D006801:Humans; D007109:Immunity; D012703:Serotyping; D012899:Smallpox / Q000145:classification / Q000453:epidemiology* / Q000635:transmission; D013020:South America; D006113:United Kingdom; D012901:Variola virus / Q000145:classification / Q000276:immunology* / Q000472:pathogenicity; D014774:Virulence; D015047:Zoonoses