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    Infectious Disease Prevention Section
    Mail Code: 1927
    PO BOX 149347 - Austin, TX 78714-9347
    1100 West 49th Street, Suite G401
    Austin, TX 78714

    Phone: (512) 776-7676
    Fax: (512) 776-7616


Acute Flaccid Myelitis

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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 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 like it, and there are different possible causes, such as viruses, toxins, and genetic disorders. Conditions like AFM can be caused by a variety of germs, including several viruses:

  • Enteroviruses
  • West Nile Virus (WNV) and viruses in the same family as WNV, specifically Japanese encephalitis virus and South Louis encephalitis viruses, and
  • Adenoviruses

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. The most severe symptom of AFM is respiratory failure that can happen when the muscles involved with breathing become weak. This can require urgent ventilator support (breathing machines).

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. Being up to date on polio vaccinations 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 vaccines.

You can protect yourself from mosquito-borne viruses such as West Nile virus—another 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, 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, and 2019. While we expected a large number of cases in 2020, researchers are still evaluating the effect of COVID-19 on AFM cases and reporting. 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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Last updated April 12, 2021