Polio is known in full as poliomyelitis - also called infantile paralysis. It is an 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. More than half of all cases of polio occur in children under the age of five. The paralysis so commonly associated with the disease actually affects fewer than 1 percent of persons infected by the poliovirus.

For those infected by the poliovirus, there is no cure, and in the mid-20th century hundreds of thousands of children were struck by the disease every year. Since the 1960s, thanks to widespread use of polio vaccines, polio has been eliminated from most of the world, and it is now endemic only in several countries of Africa and South Asia.