Symptoms of Polio
Muscle aches, fever, and abdominal pain are some of the common minor symptoms of polio. In severe cases, paralysis may result. Up to 95 percent of people who are infected with poliovirus will have no symptoms. However, they can still transmit the virus and cause polio in others.
When a person becomes infected with poliovirus, the virus begins to multiply within the cells that line the back of the throat, nose, and intestines. Symptoms of polio usually appear 7 to 14 days after a person becomes infected with the poliovirus. This period between polio transmission and the start of symptoms is called the "polio incubation period." The incubation period for polio can be as short as 4 days or as long as 35 days.
(Click Polio Incubation Period for more information about the incubation period for polio.)
Up to 95 percent of people who are infected with poliovirus will have no symptoms. However, people who are infected and do not have symptoms can still spread the poliovirus and cause others to develop polio.
If a person does develop symptoms of polio, the symptoms can be categorized into one of three groups, which include:
- Minor polio symptoms (also known as abortive poliomyelitis)
- Aseptic meningitis
- Paralytic poliomyelitis.
Minor Polio Symptoms
About 4 to 8 percent of people who are infected with the poliovirus will develop minor symptoms. These can include:
People who develop minor polio symptoms develop no paralysis or other serious symptoms. These minor symptoms last for two to three days with complete recovery.
About 1 to 2 percent of infected people will develop aseptic meningitis from poliovirus. For these people, early symptoms can be similar to minor polio symptoms. Then aseptic meningitis symptoms can develop, including stiffness of the back or legs and increased or abnormal sensations. These symptoms improve rapidly, usually within a couple of days (2-10 days) with complete recovery.