Acute Flaccid Myelitis in U.S. Children

Families may have recently heard news stories about children suddenly developing weakness in their arms or legs. The condition, called Acute Flaccid Myelitis (AFM) is extremely rare (the chances of having AFM is one in one million), but the number of cases has increased sharply in recent years (396 confirmed cases from August 2014 to September 2018). Here is what the Centers for Disease Control and Prevention (CDC) has to say about the condition.

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 and environmental toxins. AFM affects the nervous system, specifically the spinal cord, which can cause the muscles and reflexes in the body not to work normally.

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.

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 poliovirusand 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 and environmental toxins.

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 patients under investigation for AFM 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.