Acute Flaccid Myelitis in U.S. Children

CDC continues to receive reports of children with acute flaccid myelitis (AFM), a rare but serious condition. CDC is working hard to find the causes of these AFM cases. Learn more about AFM and symptoms that require immediate medical care.

Parents may be hearing about children in the United States who suddenly became weak in their arms or legs from a condition called acute flaccid myelitis, or AFM. This condition is not new, but the increase in cases we saw starting in 2014 is new. There are different possible causes, such as viruses, environmental toxins, and genetic disorders. AFM affects the nervous system, specifically the spinal cord, which can cause the muscles and reflexes in the body not to work normally.

At a Glance

CDC is concerned about AFM, a serious condition that causes weakness in the arms or legs.
From August 2014 through September 2018, CDC has received information on a total of 386 confirmed cases of AFM across the US; most of the cases have occurred in children.
Even with an increase in cases since 2014, AFM remains a very rare condition. Less than one in a million people in the United States get AFM each year.
While we don’t know the cause of most of the AFM cases, it’s always important to practice disease prevention steps, such as staying up-to-date on vaccines, washing your hands, and protecting yourself from mosquito bites.

Learn more about CDC’s investigation of AFM.

In August 2014, CDC was made aware of an increased number of people, mostly children, with AFM. Since then, we’ve been working hard to better understand AFM, what puts people at risk of getting it, and the possible causes. AFM remains rare (less than one in a million people), even with the recent increase in cases. However, AFM is serious, and we don’t yet know what causes most people to get it or how to protect people from getting AFM. As we continue to learn about AFM, we urge parents to seek medical care right away if their child develops symptoms of AFM.

Mother teaching her child how to wash hands

While we don’t know if effective in preventing AFM, washing your hands often is one of the best ways to avoid getting sick and spreading germs to other people.

Symptoms of AFM

AFM is rare, but it can lead to serious neurologic problems. You should seek medical care right away if you or your child develops any of these symptoms:

weakness and loss of muscle tone and reflexes in the arms or legs
facial droop or weakness
difficulty moving the eyes
drooping eyelids
difficulty swallowing
slurred speech

Infections That Can Cause Conditions like AFM

Certain viruses, such as poliovirus and West Nile virus, may sometimes lead to conditions like AFM. You can protect yourself and your children from these viruses by:

Making sure you are all up to date on polio vaccinations.
Protecting against bites from mosquitoes, which can carry West Nile virus, by using mosquito repellent, staying indoors at dusk and dawn (when bites are more common), and removing standing or stagnant water near your home (where mosquitoes can breed).

What CDC Is Doing About AFM

CDC has been investigating AFM since we were made aware of an increased number of people with this condition in August 2014.

We have done extensive lab testing on specimens from patients, but have not determined what caused most of these people to get AFM. It is unclear what pathogen (germ) or immune response caused the arm or leg weakness and paralysis. AFM may have a variety of possible causes such as viruses, environmental toxins, and genetic disorders.

We are continuing to learn as much as we can about AFM by looking at each case to figure out what puts people at risk of getting this condition and what is causing it. Also, we are urging doctors to be alert for patients with symptoms of AFM and to report suspected cases to their health departments.

If you would like to learn more about what CDC is doing, please visit CDC’s AFM in the United States website. If you would like to learn more about AFM, please visit CDC’s acute flaccid myelitis website.