Figure 6.

Upper panel: annual numbers of reported cases of poliomyelitis in the United States, 1951–1982. For the years 1973–1982, cases were either imported cases or cases of vaccine-associated paralytic poliomyelitis, with the exception of an outbreak that occurred among the Amish population in 1979. Data were obtained from the Centers for Disease Control and Prevention (65). Lower panel: number of US states reporting indigenous poliomyelitis due to wild polioviruses, 1951–1982. Data were obtained from the Centers for Disease Control and Prevention (69).