AFM (Acute Flaccid Myelitis)
AFM (Acute Flaccid Myelitis) is a rare but serious neurological condition. It affects the nervous system, specifically the spinal cord, causing the muscles and reflexes in the body to become weak. Since 2014, CDC has confirmed 673 cases of AFM in all 50 states and the District of Columbia. Over 90% of cases have occurred in young children. Still, CDC estimates that less than one to two in a million children in the United States will get AFM every year. While it appears that viruses play an important role in AFM, there is not one specific virus that causes the condition. Increases in cases of AFM have coincided with increases in enteroviruses in peak years. There are also no known ways to prevent AFM. The CDC has been thoroughly investigating the AFM cases that have occurred since 2014, when the first large number of cases being reported was noted.
- Since 2014, CDC has confirmed 673 cases of AFM in 50 states and the District of Columbia.
- Most cases developed symptoms between August and November.
- Prior to the COVID-19 pandemic, cases of AFM increased every 2 years, in 2014, 2016 and 2018. There have been no real spikes of AFM since 2018.
- Rhode Island has had three confirmed cases of AFM; one in 2016, one in 2018, and one in 2022.
- Updated case counts by month and state are available here.
Most patients will have sudden onset of arm or leg weakness and loss of muscle tone and reflexes. Some patients, in addition to the limb weakness, will experience any or all of the following symptoms:
- Facial droop/weakness
- Drooping eyelids
- Difficulty moving the eyes
- Difficulty with swallowing or slurred speech
- Pain in arms, legs, neck or back
Numbness or tingling is rare in patients with AFM. Some patients with AFM may be unable to pass urine. The most severe symptom of AFM is respiratory failure, which can happen when the muscles involved with breathing become weak. This can require urgent ventilator support (breathing machines). If you or your child develops any of these symptoms, you should seek medical care right away. An AFM factsheet can be found here.
How It Spreads
Certain viruses are known to cause AFM, including enteroviruses. Since 2014, most cases with AFM (more than 90%) had a mild respiratory illness or fever consistent with a viral infection before they developed AFM. Most cases had onset of AFM between August and November, with increases in AFM cases every two years since 2014. At this same time of year, many viruses commonly circulate, including enteroviruses. All the stool specimens from AFM cases that the CDC has received to date have tested negative for poliovirus.
Despite extensive laboratory testing, a single microbial cause for AFM is unable to be identified.
There is no specific prevention for AFM. However, keeping yourself safe from viruses is the best protection.
You can lower the risk of getting a virus by:
You can lower the risk of spreading a virus by:
- Cleaning and disinfecting frequently touched surfaces, including toys, mobile devices, and doorknobs.
- Covering coughs and sneezes with a tissue or upper shirt sleeve, not hands.
- Staying at home if you or your child is sick.
Testing & Diagnosis
A doctor can tell the difference between AFM and other diseases with a careful examination of the nervous system, looking at the location of the weakness, muscle tone, and reflexes, to help differentiate such patients from patients with other forms of acute flaccid paralysis (AFP). Magnetic resonance imaging (MRI) can be very helpful in diagnosing cases of AFM. Testing nerve response can also be helpful in supporting a diagnosis of AFM; it is important that the tests are performed at the appropriate time (e.g., 7-10 days after onset of weakness) to be helpful. Finally, laboratory testing of cerebrospinal fluid (CSF, the fluid bathing the brain and spinal cord) can assist with diagnosis. All of these findings put together help a clinician make a diagnosis of AFM. AFM can be difficult to diagnose due to its similarities to other neurological diseases. CDC works with states to confirm all suspected cases of AFM.
There is no specific treatment for acute flaccid myelitis, but a doctor who specializes in treating brain and spinal cord illnesses (neurologist) may recommend certain interventions on a case-by-case basis. Physical or occupational therapy may help with limb weakness caused by AFM.
Additional information is available on the CDC AFM website: