Polio is a viral disease which may affect the spinal cord causing muscle weakness and paralysis. The polio virus enters the body through the mouth, usually from hands contaminated with the stool of an infected person.Polio is more common in infants and young children and occurs under conditions of poor hygiene.PS is characterized by further weakening of muscles that were previously affected by the polio infection. Symptoms include fatigue, slowly progressive muscle weakness and deterioration. Joint pain and bone deformities are common. PPS is generally not life-threatening.