What Is Polio?
Polio is a life-threatening disease caused by a virus. It was once one of the most feared diseases in the United States, but the creation of a vaccine in the 1950s ended the threat. The U.S. is now polio-free, though travelers can still bring it into this country.
People of any age can get polio, but kids under 5 have the highest risk of getting it.
Most people who catch the poliovirus don't have symptoms. About 1 in 4 people will have symptoms that look a lot like the flu, such as:
- Sore throat
- Feeling tired
- Upset stomach
- Back or neck pain or stiffness
- Muscle weakness
- Stomach pain
"Nonparalytic polio" symptoms like these often don't cause you to become paralyzed. They usually go away on their own within 10 days.
A smaller number of people have a more severe kind of polio that's called "paralytic polio." If you have it, your symptoms will start off like the mild ones above. Within a week, you'll also start to have:
- A loss of reflexes
- Severe muscle pain or weakness
- Floppy limbs
- A feeling of pins and needles in your legs
- Paralyzed arms, legs, or both
- Meningitis (an infection in your brain, spinal cord, or both)
Polio can be life-threatening if the muscles you use to breathe get so weak that they no longer work.
Years after you have polio, you may start to have other symptoms. Known as "post-polio syndrome," you could have:
- Problems with breathing and swallowing
- Muscle loss
- Sleep disorders like sleep apnea
- Trouble handling low temperatures
Polio is different from acute flaccid myelitis (AFM), a rare but serious condition that also attacks the nervous system and causes your muscles to weaken. Some people call AFM a "polio-like" illness, but it is not the same virus.
Polio Causes and Risk Factors
You get polio from a virus. You have to come in direct contact with the virus to get it. This can be person-to-person contact, or through contact with an object that has the virus on it. When you have the virus, it lives in your throat and intestines.
The virus gets inside you through your mouth. You might get it by:
- Contact with feces from a person with polio. This can include putting an object that has feces on it in your mouth or getting feces on your hand and putting your hand in your mouth. Water or food that is contaminated with infected feces can also spread polio.
- Breathing in droplets from a cough or sneeze of a person with polio. This is a less common way to get polio.
Even if you don’t have symptoms, you can pass on polio to others if it’s in your body.
Although polio mainly affects children under 5, you’re also at high risk if you haven’t had the polio vaccine.
If you have polio, your doctor will focus on making sure that you're comfortable and try to prevent any other health issues. Some treatments and tools for support include:
- Pain relievers (like ibuprofen)
- A ventilator (a device that helps you breathe)
- Physical therapy that can help keep your muscles working
- Bed rest and fluids for flu-like symptoms
- Antispasmodic medications to relax muscles
- Antibiotics for urinary tract infections
- A heating pad for muscle aches and spasms
- Corrective braces
- Pulmonary rehabilitation to help with lung complications
- A mobility aid such as a cane, wheelchair, or electric scooter
There's no cure for polio, but a vaccine allows your body to fight off the virus.
Before the vaccine became available in the 1950s, the virus paralyzed thousands of people each year. By the 1970s, because many people had the vaccine, there were fewer than 10 cases of polio in the U.S.
There are two types of the vaccine:
Inactivated poliovirus vaccine (IPV). You get this as a shot in either your leg or your arm.
Oral poliovirus vaccine (OPV). This is an older form of the vaccine that’s still used around the world.
Today, kids in the U.S. often get four doses of the IPV vaccine, one dose each at ages:
- 2 months
- 4 months
- Between 6 and 18 months
- Between 4 and 6 years
If you're an adult who got the polio vaccine as a child, you should still be immune. The only reason you might need a booster shot is if you plan to travel to a country where polio is still common or you spend time with someone who has polio.
If you didn't have all your vaccines or are unsure, your doctor can give them to you. You'll get two shots that are 4 to 8 weeks apart, and then a third shot 6 months to a year later.
While most of the world is also polio-free, three countries -- Afghanistan, Nigeria, and Pakistan -- have not fully stopped outbreaks of the virus.
Some people can have an allergic reaction to the vaccine. Usually you’ll see any symptoms of an allergy within a few minutes to a few hours after you get it. To tell if you have an allergy to the polio vaccine, watch for:
Call your doctor right away if you have any of these signs.
Since 1988, the number of cases of polio in the world has gone down by 99%. The U.S. hasn’t had a case of polio since 1979. In 2018, sources reported only 33 cases worldwide. But while many countries are polio-free, some still actively have it. And anyone who comes into contact with the virus who hasn’t been vaccinated can get it. The best way to get rid of polio for good across the world is to make sure people are immunized.