Alerts:  Nov. 12, 2024: Pertussis (whooping cough) outbreak confirmed in Spokane County. SRHD urges parents and pregnant people to vaccinate. Read the press release.

Acute Flaccid Myelitis Advisory for Health Care Providers

Acute Flaccid Myelitis – Vigilance during Fall Respiratory Season

Posted Oct. 9, 2024. Past health advisories and alerts are archived for historical purposes and are not maintained or updated.


Current Situation

AFM is a rare but serious acute-onset paralytic disease. Although AFM can occur in people of any age, it mainly affects children.

As we enter the fall season, increased circulation of respiratory pathogens, including enteroviruses, is anticipated. Circulation of Enterovirus D-68 (EV-D68) has been associated with an increase in cases of AFM in previous years. While Washington has had zero AFM cases reported so far in 2024, at least 14 cases of AFM have been reported in the US, and wastewater monitoring has indicated increased circulation of EV-D68 in recent weeks.

Actions Requested
  • Be aware that AFM is a notifiable condition in the State of Washington.
    • Notifiable from health care providers to Spokane Regional Health District in 24 hours
  • Be aware that AFM should be suspected in patients of ANY age who present with:
    • Acute onset of flaccid weakness in one or more limbs, AND
    • An MRI showing gray matter lesions spanning one or more spinal segments.
  • In addition to AFM, clinicians and public health investigators should be encouraged to consider Polio as a differential diagnosis, especially in patients who are not vaccinated for polio and who have had recent travel to areas with high risk for polio.
  • Be aware that CDC recommends collection of several clinical specimens to aid in case confirmation, including serum, respiratory, stool, and CSF.
    • For a list of specimens and appropriate handling, refer to this table from CDC.
    • Specimens can be sent to the Washington State Public Health Laboratories (PHL) for shipping to the CDC.
      • Shipping of specimens to PHL/CDC must be arranged in advance by contacting SRHD.
Background

Cases of AFM were first reported to the CDC in 2014; surveillance for AFM in Washington was implemented in 2015.

AFM is a rare condition that affects the spinal cord, resulting in muscle and nerve weakness similar to the clinical presentation for polio. Most people with AFM have sudden onset of arm or leg weakness with loss of muscle tone and reflexes in the affected limb (or limbs). Although AFM has a variety of possible causes, it is strongly suspected that AFM is caused by a viral respiratory pathogen such as enterovirus.

Enterovirus D-68 (EV-D68) is believed to be the main enterovirus circulating in prior years with elevated cases (including 2014, 2016, and 2018). In past years, increases in EV-D68 respiratory disease have preceded cases of AFM by about 2 weeks. Although we are seeing increases in EV-D68 detections in the United States this year, the number of reported cases of AFM has remained relatively low to date. As of September 18, 2024, CDC has received 23 reports of suspected AFM, with 14 confirmed cases in 11 states. There have been no cases of AFM reported in Washington for 2024. Cases of AFM were reported in Washington in 2016 (10 confirmed cases), 2018 (11), and 2023 (1).

The identification of a paralytic polio case in an unvaccinated person in New York in 2022 reinforced the need to also consider polio in the differential diagnosis of patients with sudden onset of limb weakness. Clinicians should obtain whole stool samples from all patients with suspected AFM to rule out poliovirus infection. This is particularly important if the patient is under-vaccinated or unvaccinated against polio, and if the patient has a history of recent travel to an area at high risk for polio.

Resources
AFM
Polio
Contact

For additional questions, or to report suspect cases, please contact SRHD Epidemiology at 509-324-1442 (business hours) or 509-869-3133 (after hours).