Acute Flaccid Myelitis (AFM)

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Organism, Causative Agent, or Etiologic Agent
Acute flaccid myelitis (AFM) is a rare but serious condition that affects the nervous system, specifically the spinal cord, which can cause limb weakness and poor muscle response. This type of condition is not new.

Anyone can get AFM or neurologic conditions like it, and there are different possible causes, though there is increasing evidence since 2014 that supports viruses playing a contributing role in causing AFM. Conditions like AFM can be caused by a variety of germs; including, butpotentially not limited to:

  • Coxsackievirus A16
  • Enterovirus A71 (EV-A71)
  • Enterovirus A71 (EV-D68)

Mode of transmission is dependent on the infectious agent.

Symptoms (Clinical Illness)
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, or
  • 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. Severe symptoms of AFM can occur such as respiratory failure that can happen when the muscles involved with breathing become weak. This can require urgent ventilator support (breathing machines). Life-threatening changes in body temperature and blood pressure instability can also occur.

Incubation Period
Incubation period is dependent on the infectious agent.

Although the underlying infection may be communicable, the condition of AFM is usually a rare complication.

Prevention and Vaccination 
There is no specific vaccination for Acute Flaccid Myelitis. All the stool specimens from AFM patients that CDC received tested negative for poliovirus. This means that the cases of AFM since 2014 are not caused by poliovirus.

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, changing a baby’s diaper, or touching an animal, an animal’s food, urine or feces; and
  • before and after taking care of a sick person or a cut or wound.

School Exclusion Policy
Anyone with a fever should be excluded from work or school until 24 hours have passed fever-free without the use of an anti-fever medication. Anyone with diarrhea should be excluded from work or school until 24 hours have passed diarrhea-free without the use of an anti-diarrheal medication. If the etiology is determined, there may be additional exclusion criteria that apply 25 Tex. Admin. Code §97.7

Recent Texas Trends
Surveillance has shown us that AFM cases generally peak in the months of September and October. A biennial pattern has been observed, with the majority of cases reported in 2014, 2016, and 2018, and smaller numbers reported in 2015, 2017, 2019 and 2020. We expected a high level of AFM reporting in 2020, but case totals may have been impacted by the COVID-19 response and societal changes, such as social distancing. Currently in Texas, AFM is not a reportable condition under the Texas Administrative Code. Since AFM is a relatively new condition, to help us better understand the spectrum of AFM illness, including all possible causes, risk factors, and outcomes, information is requested on all patients with acute limb weakness. Clinicians wishing to report should send information on patients who meet the clinical criteria (acute limb weakness) regardless of any laboratory results or MRI findings.
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