What is polio?
Poliomyelitis (polio) is a disease caused by poliovirus. It happens mostly in children younger than 5 and in parts of the world that have not yet seen wide-scale vaccination.
How common is polio?
Polio is extremely rare in the United States and many other countries because most people have gotten vaccinated. In many places, polio vaccination is standard for children’s healthcare and often required for kids to attend school.
But polio remains a problem in small pockets of the world. Until everyone gets vaccinated, there is a possibility that polio can become a widespread problem again. The World Health Organization (WHO) continues to work to eliminate polio.
How common are paralysis and death from polio?
Of every 200 polio infections, one case leads to paralysis, usually in the legs. About 5% to 10% of people paralyzed by polio die because they can’t use their muscles to breathe.
Some people in the United States who had polio early in their life still need care for symptoms much later in life.
Symptoms and Causes
What causes polio?
A virus called poliovirus causes polio. The virus enters the body through the mouth or nose, getting into the digestive and respiratory (breathing) systems. It multiplies in the throat and intestines. From there, it can enter the bloodstream. It can also attack the nervous system, the nerve network that helps the brain communicate with the rest of the body.
There are three strains of poliovirus: types 1, 2 and 3. Types 2 and 3 have been eradicated (eliminated), but type 1 still affects people in a few countries.
In some parts of the world, a live poliovirus vaccine is still used. This oral live virus vaccine can very rarely cause polio. In the United States and many areas of the world, this live virus vaccine is no longer used and an inactivated vaccine that cannot cause polio is used instead.
Is poliovirus contagious?
Poliovirus is very contagious, and a person can transmit (spread) it even if they aren’t sick. The virus goes from person to person in two ways.
People with poliovirus in their bodies shed the virus through their feces (poop). The virus can then spread to other people when they swallow contaminated water or food. This exposure is more likely in areas that have poor hygiene or weak systems to clean water.
A person can also pick up the virus after someone sneezes or coughs. If you get droplets of an infected person’s phlegm or mucus in your mouth or nose, you can become infected.
What are the symptoms of polio?
About 90% of people infected with poliovirus have no signs of the disease or just mild symptoms. If symptoms do occur, they usually appear about seven to 10 days after exposure to the virus. But symptoms can take as long as 35 days to show up.
Early symptoms of polio are like those of influenza (flu) and last about two to 10 days:
While most people fully recover from polio, the disease can cause very serious problems. These problems can sometimes develop quickly (hours after infection) and include:
Diagnosis and Tests
How is polio diagnosed?
If you have symptoms of polio, contact a healthcare provider. The healthcare provider will ask you about your symptoms and whether you have traveled recently.
Because polio symptoms look a lot like flu symptoms, the healthcare provider may order tests to rule out more common viral conditions.
To confirm polio, a healthcare provider will take a small sample of:
- Cerebrospinal fluid (liquid around the brain and spinal cord).
- Saliva from your throat.
- Stool (poop).
The healthcare team will look at the sample under a microscope to identify poliovirus.
Management and Treatment
How is polio treated?
While there’s no cure for polio, and no way to prevent paralysis, some things may keep you more comfortable:
- Fluids (such as water, juice and broth).
- Heat to soothe the muscles.
- Medications that relax the muscles, also called antispasmodic drugs.
- Pain relievers, such as NSAIDs (nonsteroidal anti-inflammatory drugs).
- Physical therapy and exercises to help protect the muscles.
- Mechanical ventilation, or a machine that helps you breathe.
How do I prevent polio?
The best prevention against polio is a series of four vaccine shots in the arm or leg.
The inactivated polio vaccine used in the United States is very effective and safe, and cannot cause polio.
The recommended vaccination schedule for children is based on age:
- First shot when 2 months old.
- Second shot when 4 months old.
- Third shot between 6 and 18 months old.
- A “booster” shot when 4 to 6 years old, for an extra dose to secure protection.
If you didn’t get polio vaccines as a child, you should get three shots in adulthood:
- First dose at any time.
- Second dose a month or two later.
- Final dose six to 12 months after the second.
If you didn’t get all your vaccine doses during childhood, you should get the remaining shots as an adult.
Who should get the vaccine?
Everyone should get vaccinated for polio, preferably during childhood. But even if you’ve had all the normal polio doses, you may need a booster shot if:
- You work in a lab where you might come into contact with poliovirus.
- You work with patients who may have gotten exposed to poliovirus.
- You’re planning to travel to certain areas of the world. (Check the list of countries where polio remains a risk, and talk to your healthcare provider.)
Are polio vaccines safe?
The Centers for Disease Control and Prevention (CDC) considers polio vaccines to be very safe. The CDC tracks vaccine safety and problems.
Any vaccine may cause:
- Allergic reaction.
- Pain that lasts awhile (in rare cases).
- Redness where the needle entered the skin.
- Soreness in the area where you got the shot.
If you’re not feeling well after a shot or have an allergic reaction, tell your healthcare provider. Also touch base with your provider before future doses.
Outlook / Prognosis
Can polio come back after I recover?
About 40% of people who previously had polio and recovered can develop post-polio syndrome. The syndrome can occur up to 40 years after the initial disease. If a person had a bad case of polio, then post-polio syndrome may be more severe. If a person had a less serious case of polio, they may not get post-polio syndrome or only have a mild case.
What does post-polio syndrome feel like?
Symptoms of post-polio syndrome may start slowly and then get worse. They’re like the symptoms of polio:
- Muscle atrophy (slow decrease in muscle size).
- New weakness in the same muscles that polio affected.
- Pain in the joints.
- Scoliosis (curved spine).
Symptoms of post-polio syndrome are rarely life-threatening, but they can cause difficulties with:
- Participating in normal activities.
Is post-polio syndrome contagious, too?
Post-polio syndrome is not contagious. Only someone who once had polio can have the syndrome.
What can I ask my healthcare provider about polio?
Consider asking your healthcare provider:
- Is it possible that something else is causing the symptoms?
- Am I contagious? For how long?
- Can I go to work or school?
- What can I do to make sure I don’t infect other people?
- When will I feel better?
- Will I have any long-term problems from the disease?
A note from Cleveland Clinic
Polio is a serious condition but very rare in the United States thanks to vaccination. Everyone should get a series of vaccine shots. People who plan to travel to certain countries or work near poliovirus should get a booster shot. Talk to your healthcare provider if you need to get vaccinated.
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