Poliomyelitis (polio) is a highly infectious viral disease, which mainly affects young children. The virus is transmitted through contaminated food and water, and multiplies in the intestine, from where it can invade the nervous system. Many infected people have no symptoms, but do excrete the virus in their faeces, hence transmitting infection to others.
Major polio epidemics were seen in the 20th century before the development of a vaccine by Jonas Salk and Albert Sabin in the 1950’s.
The University of Oxford