How Is Polio Spread?
Following polio transmission, a person does not immediately become sick. Once the poliovirus enters the body, it travels to the back of the throat, nose, and intestines, where it begins to multiply and travel to other parts of the body. After 7-14 days (on average), symptoms of polio can begin. This period between polio transmission and the beginning of polio symptoms is called the polio incubation period. The incubation period can be as short at 4 days or as long as 35 days.
(Click Polio Symptoms for more information about the symptoms of polio.)