Polio is an infection caused by a virus, called the poliovirus. It was once very common in the U.S. and feared, because it caused paralysis and could be deadly. After doctors started giving a polio vaccine in the 1950s, the number of cases fell rapidly. No new cases of polio have started in the U.S. since 1979. But it is still a problem in parts of Asia and Africa.
Most people who get infected with polio (short for poliomyelitis) have no symptoms.
Some people have only mild flu-like symptoms, so they may not even suspect that they have polio. These symptoms can include:
Rarely, the virus affects the brain and spinal cord, causing much more serious symptoms, such as:
Polio is very contagious. The virus enters the body through the mouth and grows in the throat and intestines. It then spreads to other people via saliva (spit) or feces (poop). People can come into contact with the virus when:
An infected person can have the virus in their throat for 1–2 weeks, and in their poop for up to 6 weeks or longer. Even someone who has no symptoms can pass the virus to other people.
There is no cure for polio, only treatments to manage symptoms. Mild cases usually are treated with plenty of fluids and bed rest.
Someone who has muscle pain or weakness will get medicine to treat the pain, and physical therapy to keep the muscles moving. If their breathing muscles are affected, they might need help from a mechanical ventilator (breathing machine). The ventilator moves air in and out of the lungs until the person can do it on their own.
People who have milder polio symptoms usually make a full recovery within 1–2 weeks. People whose symptoms are more severe can be weak or paralyzed for life, and some may die.
After recovery, a few people might develop "post-polio syndrome" as long as 30–40 years after their initial illness. Over time, they develop pain or weakness in their muscles or joints, and might feel very tired.
Polio is a preventable disease. The best way to protect children is to make sure they get a polio vaccine. The vaccine makes the infection-fighting immune system create antibodies against the virus. The antibodies will fight the virus if it ever enters the body.
In the U.S., kids get the inactivated poliovirus vaccine (IPV) when they're 2 months, 4 months, 6–18 months, and 4–6 years old. IPV contains an inactive form of the virus, so it can't cause polio.
In other parts of the world, kids might also get oral polio vaccine (OPV). This liquid vaccine is cheaper and easier to give to many people. Because it's not an injection, it doesn't have to be given by a trained health care provider.
OPV will be in the spit and poop of those who get the vaccine. So it can spread to other people the same way the virus does. If it spreads to someone who isn't vaccinated, it can trigger that person's immune system to create antibodies. They'll be immunized even though they didn't get the vaccine directly.
OPV contains a weak form of the live virus, so very rarely it can cause polio. That's why it is no longer used in the U.S.
OPV doses given before April 2016 can count toward a child's U.S. polio vaccination requirements. Doses given after that will not count.
Health groups are working to wipe out polio throughout the world, with much success. But several countries still have polio. If you plan to travel outside the U.S., particularly to Africa and Asia, be sure that you and your kids have gotten all your needed polio vaccinations.
Reviewed by: Elana Pearl Ben-Joseph, MD
Date Reviewed: 10-02-2020
