There are 15-20 million polio survivors in our world.  And 60-75% are subject to having Post Polio Syndrome.
Trouble Years Later - According to the diagnostic criteria developed by the March of Dimes, Post polio Syndrome is new muscle weakness or decreased endurance that occurs in people with a history of paralytic polio, after partial or complete recovery from the infection and a long interval — typically 15 to 30 years — of stable functioning. The weakness comes on gradually, persists for at least a year, progresses slowly, and can be accompanied by fatigue, muscle wasting, and muscle and joint pain. Some patients also develop sleeping problems, breathing problems, and difficulty swallowing.