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Acute Flaccid Myelitis

Acute flaccid myelitis (AFM) is a condition that affects the nervous system, specifically the spinal cord, which can result from a variety of causes including viral infections. Viruses associated with AFM include:

  • 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,
  • herpesviruses, such as cytomegalovirus and Epstein-Barr virus, and
  • adenoviruses.

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).

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.

In Alaska, clinicians should be vigilant for and report to the Section of Epidemiology (SOE) all patients with sudden onset of neurologic illness associated with limb weakness that meets the case definition below for acute flaccid myelitis regardless of any laboratory results. Reports may be made to SOE by phone 907-269-8000 or afterhours at 800-478-0084.

AFM Surveillance

As of December 31, 2022, there have been four cases of AFM in Alaska since we began tracking AFM in August 2014. These cases were reported to the Centers for Disease Control and Prevention; one probable case in 2021, one confirmed case in 2020, and two cases, one confirmed and one probable, in 2016. These cases involved both young children and adolescent-aged people.

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