Polio (full name: poliomyelitis) is an infectious disease caused by the poliovirus. It is transmitted through contact with an infected person primarily through the fecal-oral route. The virus enters the body through the mouth or respiratory system and multiplies in the throat and intestines. It can travel through the blood and may enter the central nervous system (spinal cord and brain), causing muscle weakness, paralysis, and in some cases, even death. The virus exits the body through the feces (stool).
The term “polio” refers to the paralytic form of the disease. Only those with this condition are said to have polio. Polio is fatal in 2-10% of cases for those who have the paralytic form because the muscles that are required for breathing cannot function normally.
Post-polio syndrome can occur from 15 to 40 years after the initial infection. Up to 40% of patients who survive paralytic polio may develop post-polio syndrome in the future. They might experience muscle pain, weakness or even paralysis many years after their original illness.
Polio is caused by the poliovirus. The virus enters the body through the mouth. It is spread through contact with the feces (stool) of an infected person or through exposure to phlegm or mucus when an infected person coughs or sneezes. Polio can also be transmitted by handling objects that are contaminated with fecal matter containing the virus and then putting your hands in your mouth. Poor hygiene or unsanitary conditions leading to contamination of food or water supplies with the virus have also been linked to polio outbreaks.
A person who is infected with the virus can remain contagious for 1 or 2 weeks after symptoms first appear. An infected person can carry the virus and infect others even if he or she does not appear to be sick.
Although people of any age can get polio, children age 5 or younger are at greater risk of infection.
Most people (about 72%) who are infected with the poliovirus will not show any apparent symptoms.
Another 25% of those infected will experience symptoms that are similar to those of the flu, including:
These symptoms usually last for 2 to 5 days, and then disappear.
However, a smaller number of people develop more severe symptoms that are due to involvement of the spinal cord and brain.
These symptoms include:
About 1 in 200 people who are infected with the poliovirus will experience paralysis, which may result in permanent damage or death.
The doctor will ask questions about the patient’s symptoms and medical history, including whether he or she has recently traveled to areas where cases of polio were reported. The doctor will perform a physical examination.
Symptoms of polio may resemble those of other viral diseases, so tests will be required to rule out other causes. If the doctor suspects you have the virus, stool specimens and throat swabs will be collected for testing. Two stool specimens and 2 throat swabs should be collected 24 hours apart. Specimens should be obtained as early as possible after the onset of disease, preferably within 14 days. Blood samples might also be collected for analysis.
A lumbar puncture (spinal tap) may be performed to collect cerebrospinal fluid to look for evidence of the polio virus infection.
Unfortunately, there is no cure for polio. Supportive measures may be taken to ease some of the symptoms and give the body time to recover. Pain relievers, such as ibuprofen, may be given to reduce pain and fever. Fluids and bed rest are helpful for those with mild flu-like symptoms. Physical therapy can be provided to stimulate the muscles and increase mobility for those who become disabled. A mechanical ventilator may be required for patients who have difficulty with breathing.
The poliovirus has been eradicated in the United States since 1979, thanks to the use of effective vaccines; however, polio still remains a problem in some parts of the world.
The polio vaccine is safe and highly effective in protecting children from polio. About 99 out of 100 children who are fully vaccinated will not get polio.
There are 2 types of polio vaccine that are currently available. Only the inactivated poliovirus vaccine (IPV) is used in the United States. The other type, the oral poliovirus vaccine (OPV), is used throughout some other parts of the world.
The IPV is given as an injection in the arm or leg. Sometimes it is administered along with other vaccines.
Children should receive 4 doses of the polio vaccine, according to the following vaccination schedule.
First dose: 2 months of age
Second dose: 4 months
Third dose: 6 to 18 months
Booster dose: 4 to 6 years
Children who will be traveling to other parts of the world where polio cases have been reported during the previous year should be fully vaccinated before they travel. This might require an accelerated vaccination timetable so all of their injections are given before they travel to high-risk locations.
Some adults might not have been fully vaccinated against polio when they were children. In these cases, it is recommended that they receive 3 doses of the inactivated polio vaccine (IPV).
The first dose may be given at any time, followed by a second dose 1 to 2 months later. The final dose should be given within 6 to 12 months after the second dose.
Adults who have already received 1 or 2 doses of the vaccine should get the remaining injection(s) at some point in their lives.
Adults who are at higher risk of becoming infected with polio include those who:
Adults at high risk of exposure to polio may receive one booster shot during their lives.
The Centers for Disease Control and Prevention website posts travel health notices with information about areas where polio cases have recently been reported.
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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or healthcare provider. Please consult your healthcare provider for advice about a specific medical condition. This document was last reviewed on: 12/07/2014