Selective epidemiologic control in smallpox eradication.
D000350:Africa, Central; D000354:Africa, Western; D004196:Disease Outbreaks / Q000517:prevention & control*; D006801:Humans; D011159:Population Surveillance; D012621:Seasons; D012899:Smallpox / Q000453:epidemiology / Q000517:prevention & control*; D014611:Vaccination; D014944:World Health Organization