Infection affects the gastrointestinal tract and nasopharynx, but frequently is asymptomatic.
The CNS is affected in exceptional cases, leading to paralysis. Derangement in size and number of muscle fibers occurring with aging, reduction in blood supply, or following immobilization, prolonged weightlessness, malnutrition, and particularly in denervation. Provides information and advice to people with polio and their families. Has an informative website.