"Polio, short for poliomyelitis, or infantile paralysis, is an infectious disease caused by the poliovirus. In about 0.5 percent of cases, there is muscle weakness resulting in an inability to move. This can occur over a few hours to a few days. The weakness most often involves the legs, but may less commonly involve the muscles of the head, neck and diaphragm. Many people fully recover. In those with muscle weakness, about 2 to 5 percent of children and 15 to 30 percent of adults die. Another 25 percent of people have minor symptoms such as fever and a sore throat, and up to 5 percent have headache, neck stiffness and pains in the arms and legs. These people are usually back to normal within one or two weeks. In up to 70 percent of infections there are no symptoms. Years after recovery, post-polio syndrome may occur, with a slow development of muscle weakness similar to that which the person had during the initial infection." - (en.wikipedia.org 11.12.2019)
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