Post polio syndrome (PPS) is a condition that affects polio survivors anywhere from 10 to 40 years after recovery from an initial paralytic attack of the poliomyelitis virus. PPS is characterized by a further weakening of muscles that were previously affected by the polio infection. The most common symptoms include slowly progressive muscle weakness, fatigue (both general and muscular), and a decrease in muscle size (muscular atrophy). Pain from joint deterioration and increasing skeletal deformities such as scoliosis are common. Some individuals experience only minor symptoms, while others develop more visible muscle weakness and atrophy. PPS is rarely life-threatening but the symptoms can interfere significantly with the individual's capacity to function independently. While polio is contagious, PPS is not transmissible.