Polio is a contagious viral illness that in its most severe form causes nerve injury leading to paralysis, difficulty breathing and sometimes death.
In the U.S., the last case of naturally occurring polio was in 1979. Today, despite a worldwide effort to wipe out polio, poliovirus continues to affect children and adults in parts of Asia and Africa.
The Centers for Disease Control and Prevention (CDC) advises taking precautions to protect yourself from polio if you're traveling anywhere there's a risk of polio.
Adults who have been vaccinated who plan to travel to an area where polio is occurring should receive a booster dose of inactivated poliovirus vaccine (IPV). Immunity after a booster lasts a lifetime.
Although polio can cause paralysis and death, the majority of people who are infected with the virus don't get sick and aren't aware they've been infected.
Some people who develop symptoms from the poliovirus contract 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 can last up to 10 days, include:
- Sore throat
- Back pain or stiffness
- Neck pain or stiffness
- Pain or stiffness in the arms or legs
- Muscle weakness or tenderness
This most serious form of the disease is rare. Initial signs and symptoms of paralytic polio, such as fever and headache, often mimic those of nonparalytic polio. Within a week, however, other signs and symptoms appear, including:
- Loss of reflexes
- Severe muscle aches or weakness
- Loose and floppy limbs (flaccid paralysis)
Post-polio syndrome is a cluster of disabling signs and symptoms that affect some people years after having polio. Common signs and symptoms include:
- Progressive muscle or joint weakness and pain
- Muscle wasting (atrophy)
- Breathing or swallowing problems
- Sleep-related breathing disorders, such as sleep apnea
- Decreased tolerance of cold temperatures
When to see a doctor
Check with your doctor for polio vaccination recommendations before traveling to a part of the world where polio still occurs naturally or where oral polio vaccine (OPV) is used, such as Central and South America, Africa and Asia.
Additionally, call your doctor if:
- Your child hasn't completed the vaccine series
- Your child has an allergic reaction to the polio vaccine
- Your child has problems other than a mild redness or soreness at the vaccine injection site
- You had polio years ago and are now having unexplained weakness and fatigue
Poliovirus can be transmitted through direct contact with someone infected with the virus or, less commonly, through contaminated food and water. People carrying the poliovirus can spread the virus for weeks in their feces. People who have the virus but don't have symptoms can pass the virus to others.
Polio mainly affects children younger than 5. However, anyone who hasn't been vaccinated is at risk of developing the disease.
Paralytic polio can lead to temporary or permanent muscle paralysis, disability, bone deformities and death.
The most effective way to prevent polio is vaccination.
Most children in the United States receive four doses of inactivated poliovirus vaccine (IPV) at the following ages:
- Two months
- Four months
- Between 6 and 18 months
- Between ages 4 and 6 when children are just entering school
IPV is safe for people with weakened immune systems, although it's not certain just how protective the vaccine is in cases of severe immune deficiency. Common side effects are pain and redness at the injection site.
Allergic reaction to the vaccine
IPV can cause an allergic reaction in some people. Because the vaccine contains trace amounts of the antibiotics streptomycin, polymyxin B and neomycin, it shouldn't be given to anyone who's reacted to these medications.
Signs and symptoms of an allergic reaction usually occur within minutes to a few hours after the shot. Watch for:
- Difficulty breathing
- Hoarseness or wheezing
- Rapid heart rate
If you or your child has an allergic reaction after any shot, get medical help immediately.
In the U.S., adults aren't routinely vaccinated against polio because most are already immune, and the chances of contracting polio are minimal. However, certain adults at high risk of polio who have had a primary vaccination series with either IPV or the oral polio vaccine (OPV) should receive a single booster shot of IPV.
A single booster dose of IPV lasts a lifetime. Adults at risk include those who are traveling to parts of the world where polio still occurs or those who care for people who have polio.
If you're unvaccinated or your vaccination status is undocumented, get a series of primary polio vaccination shots — two doses of IPV at four- to eight-week intervals and a third dose six to 12 months after the second dose.