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10 Questions About Polio

1. What is polio?

Polio, or poliomyelitis, is a disease caused by the poliovirus. It can cause permanent paralysis or even death. The disease has existed for thousands of years. The U.S. experienced an outbreak in the 1940s and 1950s, disabling about 35,000 each year until the polio vaccine was developed in 1955. Polio was eliminated from the U.S. in 1994.

The virus spreads through person-to-person contact. Polio sheds primarily in the stool but can also spread via respiratory droplets such as a sneeze or cough from an infected person. If droplets or stool of an infected person contaminate an object that is used by someone else, infection can spread that way as well. The shedding of feces may persist for several weeks.

2. Why is there a reemergence of polio?

People who are not vaccinated against polio are at risk of infection. Polio recently reemerged in New York from an unvaccinated individual and has been detected in wastewater. The origination of this case is under investigation. In past infections, a person typically contracted polio in a different country and brought it back to the U.S.

3. How do you know if you have polio?

According to the Centers for Disease Control and Prevention (CDC), most people who get infected (about 72 out of 100) will not have any visible symptoms.

"About 70% of children who are infected do not have symptoms, but they can transmit the infection for up to several weeks," says Sankar Swaminathan, MD, chief of the Division of Infectious Diseases at University of Utah Health. Some people (about 1 out of 4 people) may experience flu-like symptoms that can last two to five days.

4. What are some of the serious symptoms of polio?

The poliovirus can have devastating consequences. Those who develop more serious symptoms can experience:

  • Paralysis: This is the most severe symptom associated with poliovirus, according to the CDC. A person experiences muscle weakness in the face or other parts of the body. Some may experience permanent paralysis or death. About 1 in 200 people who get polio suffer irreversible paralysis. Between 2-10 percent of those who become paralyzed will die.
  • Atrophy of the limbs: The shrinking of muscles in the arms, legs, or both.
  • Meningitis: An infection of the covering of the spinal cord or brain.
  • Post-polio syndrome (PPS): People who fully recovered from polio can experience new muscle pain, weakness, or paralysis 15 to 40 years later. Symptoms can range from mild to severe. People with PPS are not contagious

5. How contagious is polio?

Polio is extremely contagious. It can be spread if an infected person is not experiencing any symptoms.

6. Can polio be prevented?

Polio is preventable by the polio vaccine, called inactivated polio vaccine (IPV). At least 99% of people are fully immune after three doses. There are three types of polio. IPV is the only polio vaccine given in the US and protects you against all three types of poliovirus. IPV does not contain live virus and cannot give you polio.

The polio vaccine is part of routine childhood immunization. The CDC recommends children to get four doses of the polio vaccine at the following ages:

  • 2 months
  • 4 months
  • 6 - 18 months
  • 4 - 6 years

Adults who are not vaccinated against polio or who did not complete their polio vaccine series as a child should get vaccinated right away. An individual is not fully protected against polio until they complete their vaccine series.

7. Are there any treatments for polio?

No. A cure for polio does not exist.

8. Who is most at risk of contracting polio?

Unvaccinated individuals or people who did not complete their IPV series are most at risk of getting infected. You are also at higher risk if traveling to a country where the risk of getting polio is higher.

Adults who have been fully vaccinated against polio but are at increased risk of contact with poliovirus can receive a lifetime booster dose of IPV.

9. How do you know if you've been vaccinated against polio?

A documented record of the full IPV series is the best proof.

"If you are over 18 and were born and resided in the U.S., you are considered almost certain to have been vaccinated," Swaminathan says. "Since circulation of polio is currently minimal, it is not recommended to get vaccinated."

If vaccination history is unclear or if the person is likely to come into contact with polio—due to exposure or if traveling to an area where polio is still present—revaccination may be recommended.

10. If a person was previously vaccinated against polio, are they still protected?

Yes. A person is considered protected against polio after completing their four-dose IPV series as a child. Re-vaccination is not recommended except in special circumstances.