It once affected mostly infants and children, but now is mostly seen in people over 15 years old. It is more common in the summer and fall. Adults and young girls are more likely to be infected, but infection in young boys is more likely to result in paralysis . Between 1840 and the 1950s, polio was a worldwide epidemic. Since the development of polio vaccines, the incidence is much reduced.
Outbreaks still occur, usually in non-immunized groups.
Poliomyelitis Please read this Important notice . Please read it.