Poliomyelitis
What is Poliomyelitis ?
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. A 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.
The U.S. Centers for Disease Control and Prevention (CDC) publishes travel notices of countries where there is a higher risk of polio. Countries at a higher risk of polio are generally in Africa, the Middle East, and southern and central Asia. Vaccinated adults who plan to travel to an area where polio is spreading should get a booster dose of inactivated poliovirus vaccine (IPV). Immunity after a booster lasts a lifetime.
Symptoms
- Fever
- Headache
- Muscle aches
- Sore throat
- Stomachache
- Loss of appetite
- Nausea
- Vomiting
- Neck pain or stiffness
- Aches or stiffness in the arms or legs
- Severe headache
- Stiffness of the spine and neck
Cause
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. The naturally occurring poliovirus, called the wild-type poliovirus, has been eliminated in most countries and causes few cases of polio. Another version of the virus, called the vaccine-derived poliovirus (VDPV), is more widespread and now causes most infections worldwide. VDPV exists mainly in a few countries that use an oral vaccine with a weakened poliovirus. The weakened virus in the oral vaccine doesn’t itself cause polio, and vaccinated people rarely contract VDPV. Instead, VDPV is a new version of the virus that develops within a community or region where not enough people are vaccinated. Even though the weakened virus in the oral vaccine doesn’t cause illness, it can spread. If most people in a community are vaccinated, the spread of the weakened virus is controlled. If many people aren’t vaccinated, the weakened virus can move through a community for a long time. This gives the virus the chance to change, or mutate, and behave like the wild-type virus that causes illness. Infections from VDPV have been reported in the United States. In each case, the person was either not vaccinated or had a significantly weakened immune system. One case in New York in 2022 was in a county with a lower-than-average polio vaccination rate. Samples from wastewater showed that VDPV was spreading in some communities. Since 2000, polio vaccination in the United States has used an injected vaccine with an inactivated poliovirus that doesn’t create the risk for VDPV.
Risk Factors
Polio mainly affects children. But anyone who hasn’t been vaccinated is at risk of getting the disease.
When to see a Doctor
Signs and symptoms of polio are similar to other viral diseases that affect the nervous system. It’s important to get a timely and accurate diagnosis. If you had polio before, see your health care provider if you have new or worse signs or symptoms.