Polio

polio, in full poliomyelitis, also called infantile paralysis, acute viral infectious disease of the nervous system that usually begins with general symptoms such as fever, headache, nausea, fatigue, and muscle pains and spasms and is sometimes followed by a more serious and permanent paralysis of muscles in one or more limbs, the throat, or the chest. The paralysis commonly associated with polio actually affects fewer than 1 percent of infected persons. For those who become infected, there is no cure; however, between 5 and 10 percent of infected persons display only the general symptoms outlined above, and more than 90 percent show no signs of illness at all.

More than half of all cases of polio occur in children under age five. In the mid-20th century hundreds of thousands of children were struck by the disease every year. Since the 1960s, however, thanks to widespread use of polio vaccines, polio has been eliminated from most of the world. By 2022 the disease was endemic in only two countries: Afghanistan and Pakistan.

polio testing

There are three known serotypes (closely related though distinguishable forms) of wild poliovirus: PV1, PV2, and PV3. The most widespread serotype is PV1. Both PV2 and PV3 have been eradicated.