Polio, or poliomyelitis, is a disabling and life-threatening disease caused by the poliovirus. Many people who are infected with the poliovirus don’t become sick and have no symptoms. However, those who do get sick develop paralysis, which can sometimes be fatal. This data includes confirmed polio cases, including those confirmed clinically, epidemiologically, or by laboratory investigation. Cases that have been discarded following laboratory investigation should not be included.

Source: World Health Organization