AFM (Acute Flaccid Myelitis)

AFM (Acute Flaccid Myelitis) is a rare but serious condition that affects the nervous system, specifically the spinal cord, which can cause the muscles and reflexes in the body not to work normally. This type of condition is not new. Anyone can get AFM or neurologic conditions similar to it, and there are different possible causes, such as viruses, toxins, and genetic disorders. There are also no known ways to prevent AFM. Due to a nationwide increase in cases in 2016, the U.S. Centers for Disease Control and Prevention (CDC) is intensifying efforts to understand the cause and risk factors associated with the disease.

  • Nationwide, 132 people in 37 states were reported in 2016 among persons 6 months to 64 years of age.
  • Rhode Island had one confirmed case of AFM in 2016.

At-Risk Populations


Most patients will have sudden onset of limb weakness and loss of muscle tone and reflexes. Some patients, in addition to the limb weakness, will experience:

  • Facial droop/weakness
  • Difficulty moving the eyes
  • Drooping eyelids
  • Difficulty moving the eyes
  • Difficulty with swallowing or slurred speech

Numbness or tingling is rare in patients with AFM, though some patients have pain in their arms or legs. 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.

How It Spreads

There are many causes of AFM, including:

  • Enteroviruses (polio and non-polio)
  • West Nile virus (WNV) and viruses in the same family as WNV, specifically Japanese encephalitis virus and Saint Louis encephalitis virus, and
  • Adenoviruses

AFM is one of a number of conditions that can result in neurologic illness with limb weakness. Such illnesses can result from a variety of causes, including viral infections, environmental toxins, genetic disorders, and Guillain-Barre syndrome, a neurologic disorder caused by an abnormal immune response that attacks the body’s nerves. Oftentimes, however, despite extensive laboratory testing, a cause for AFM is unable to be identified.


Being up to date on polio shots is one way to protect yourself and your family. Check with your doctor to make sure your family is up to date on all recommended shots. You can protect yourself from mosquito-borne viruses such as West Nile virus—a known cause of acute flaccid myelitis — by using mosquito repellent and staying indoors at dusk and dawn, which is the prime period that mosquitoes bite. Removal of standing or stagnant water from nearby property to minimize the number of mosquitoes is also recommended. While we don’t know if effective in preventing AFM, washing your hands the right way is one of the best things you and your children can do to protect against getting sick. Wash your hands:

  • Before you touch food
  • After going to the bathroom, blowing your nose, or changing a baby’s diaper
  • Touching an animal, an animal’s food, urine or feces
  • Before and after taking care of a sick person or a cut or wound

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, by testing the cerebrospinal fluid (CSF, the fluid bathing the brain and spinal cord), clinicians can look for findings suggestive of AFM. All of these findings put together help a clinician make a diagnosis 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.