Polio is an illness caused by a virus that mainly affects nerves in the spinal cord or brain stem. In its most severe form, polio can lead to a person being unable to move certain limbs, also called paralysis. It can also lead to trouble breathing and sometimes death. The disease also is called poliomyelitis.

 

vaccination effort throughout the world has led to only a small number of cases to occur around the world in recent years. But poliovirus still spreads within areas with low vaccination rates.

 

Most people infected with the virus that causes polio, called poliovirus, do not get symptoms.

 

About 5% of people with the poliovirus get a mild version of the disease called abortive poliomyelitis. This leads to flu-like symptoms that last 2 to 3 days. These include:

 

A more severe form of the disease, called nonparalytic polio, affects about 1% of those infected. While the illness lasts longer than a few days, it does not cause paralysis. Besides having more-severe flu-like symptoms, nonparalytic polio symptoms may include:

 

A second phase of symptoms may follow, or a person may seem to be getting better for a few days before a second phase starts. These symptoms include:

 

This most serious form of the disease is rare. The disease begins much like nonparalytic polio. But it progresses to more-severe signs and symptoms, including:

 

Any combination of limbs may experience paralysis. But paralysis of one leg is most common, followed by paralysis of one arm.

 

Depending on the severity of disease, other signs or symptoms may include:

 

Post-polio syndrome is the appearance of new signs or symptoms or the progression of problems. This usually happens decades after having polio. Common signs and symptoms include:

 

 

 

Polio is caused by the poliovirus. It mainly targets nerve cells in the spinal cord and brain stem that control muscle movement. Nerve cells controlling sensation are generally not affected.

 

People carrying the poliovirus — even people who do not get sick — can pass along the virus in feces, also called stool, or droplets from sneezing or coughing. The virus enters another person through the mouth. The virus can spread easily. For example, the virus can spread if people have not washed their hands after coughing, using the toilet or before eating.

 

The virus also may be in water contaminated with faeces carrying the poliovirus.

 

Polio mainly affects children. But anyone who has not been vaccinated is at risk of getting the disease.

 

Complications

Severe disease that affects the ability to breathe can cause death. Long-term complications for people who recover may include:

 

 

The CDC recommends four doses of inactivated poliovirus vaccine (IPV) at the following ages:

 

Between ages 4 and 6 when children are just entering school

If your child is missing a dose, talk to your health care provider about a catch-up schedule for vaccination.