On Tuesday, October 17, CDC hosted a media telebriefing on acute flaccid myelitis (AFM) in the U.S. featuring Dr. Nancy Messonnier, director of CDC’s National Center for Immunization and Respiratory Diseases. Portions of the transcript are reprinted below. Visit https://www.cdc.gov/acute-flaccid-myelitis/afm-surveillance.html for up-to-date information. 

AFM is a rare, but serious condition that affects the nervous system. It specifically affects the area of spinal cord called gray matter and causes muscles and reflexes to become weak. We know this can be frightening for parents. I know many parents want to know what the signs and symptoms are that they should be looking for in their child. I encourage parents to seek medical care right away if you or your child develop sudden weakness or loss of muscle tone in the arms or legs. CDC has been actively investigating AFM, testing specimens and monitoring disease since 2014 when we first saw an increase in cases. The number of cases reported in this time period in 2018 is similar to what was reported in the fall of 2014 and 2016. 

We expect that the case count may vary from week to week as our experts work with local and state health departments. Based on previous years, most AFM cases occur in the late summer and fall. CDC recently received increased reports for patients suspected to have AFM with an onset of symptoms in August and September. With enhanced efforts working with state and local health departments and hospitals we were able to confirm a number of these cases faster.

We understand that people, particularly parents, are concerned about AFM. Right now, we know that poliovirus is not the cause of these AFM cases. CDC has tested every stool specimen from the AFM patients, none of the specimens have tested positive for the poliovirus. AFM can be caused by other viruses, such as enterovirus and West Nile virus, environmental toxins and a condition where the body’s immune system attacks and destroys body tissue that it mistakes for foreign material. While we know that these can cause AFM, we have not been able to find a cause for the majority of these AFM cases. We continue to investigate to better understand the clinical picture of AFM cases, risk factors and possible causes of the increase in cases.

Since 2014, CDC has learned the following about the AFM cases:

• Most patients are children.
• The patients’ symptoms have been most similar to complications of infection with certain viruses, including poliovirus, non-polio enteroviruses, adenoviruses, and West Nile virus.
• All of the AFM cases have tested negative for poliovirus.
• Enteroviruses most commonly cause mild illness. They can also cause neurologic illness, such as meningitis, encephalitis, and AFM, but these are rare.
• CDC has tested many different specimens from AFM patients for a wide range of pathogens (germs) that can cause AFM. To date, no pathogen (germ) has been consistently detected in the patients’ spinal fluid; a pathogen detected in the spinal fluid would be good evidence to indicate the cause of AFM since this condition affects the spinal cord.
• The increase in AFM cases in 2014 coincided with a national outbreak of severe respiratory illness among people caused by enterovirus D68 (EV-D68). Among the people confirmed with AFM, CDC did not consistently detect EV-D68 in every patient. Learn more about EV-D68.

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

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:

• You can protect yourself and your children from poliovirus by getting vaccinated. Polio vaccine contains inactivated (not live) virus, and protects against poliovirus. This vaccine does not protect against other viruses that may cause AFM.
• You can protect 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).
• While we don’t know if it is effective in preventing AFM, washing your hands often with soap and water is one of the best ways to avoid getting sick and spreading germs to other people.