Polio is a contagious viral illness that in its most severe form causes paralysis, difficulty breathing and sometimes death.

In the U.S., the last case of naturally occurring polio happened in 1979. Today, despite a concerted global eradication campaign, poliovirus continues to affect children and adults in Afghanistan, Pakistan and some African countries.

The Centers for Disease Control and Prevention (CDC) advises taking precautions to protect against polio if you're traveling anywhere there's a risk of polio.

If you're a previously vaccinated adult who plans to travel to an area where polio is occurring, you should receive a booster dose of inactivated poliovirus vaccine (IPV). Immunity after a booster dose lasts a lifetime.

Symptoms Causes Risk factors Complications Prevention

Although polio can cause paralysis and death, the vast majority of people who are infected with the poliovirus don't become sick and are never aware they've been infected with polio.

Nonparalytic polio

Some people who develop symptoms from the poliovirus contract nonparalytic polio — a type of polio that doesn't lead to paralysis (abortive polio). This usually causes the same mild, flu-like signs and symptoms typical of other viral illnesses.

Signs and symptoms, which generally last one to 10 days, include:

  • Fever
  • Sore throat
  • Headache
  • Vomiting
  • Fatigue
  • Back pain or stiffness
  • Neck pain or stiffness
  • Pain or stiffness in the arms or legs
  • Muscle weakness or tenderness
  • Meningitis

Paralytic polio

In rare cases, poliovirus infection leads to paralytic polio, the most serious form of the disease. Paralytic polio has several types, based on the part of your body that's affected — your spinal cord (spinal polio), your brainstem (bulbar polio) or both (bulbospinal polio).

Initial signs and symptoms of paralytic polio, such as fever and headache, often mimic those of nonparalytic polio. Within a week, however, signs and symptoms specific to paralytic polio appear, including:

  • Loss of reflexes
  • Severe muscle aches or weakness
  • Loose and floppy limbs (flaccid paralysis), often worse on one side of the body

Post-polio syndrome

Post-polio syndrome is a cluster of disabling signs and symptoms that affect some people several years — an average of 35 years — after they had polio. Common signs and symptoms include:

  • Progressive muscle or joint weakness and pain
  • General fatigue and exhaustion after minimal activity
  • Muscle atrophy
  • Breathing or swallowing problems
  • Sleep-related breathing disorders, such as sleep apnea
  • Decreased tolerance of cold temperatures
  • Cognitive problems, such as concentration and memory difficulties
  • Depression or mood swings

When to see a doctor

Be sure to check with your doctor for polio vaccination recommendations before traveling to a part of the world where polio may still occur naturally, or where oral polio vaccine (OPV) is still used, such as Central and South America, Africa and Asia. In countries that use the OPV — vaccine made with live, but weakened (attenuated) polio virus — the risk of paralytic polio to travelers is extremely low, but not zero.

Additionally, call your doctor if:

  • Your child hasn't completed the series of polio vaccinations
  • Your child experiences an allergic reaction after receiving polio vaccine
  • Your child has problems other than a mild redness or soreness at the vaccine injection site
  • You have questions about adult vaccination or other concerns about polio immunization
  • You had polio years ago and are now experiencing unexplained weakness and fatigue

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