Provider Alert: Watch for cases of Acute Flaccid Myelitis

Current Situation

Acute Flaccid Myelitis (AFM) is a rare but serious acute-onset paralytic disease, which presents with symptoms similar to poliomyelitis. AFM occurs in patients of any age, but mainly affects children.

The Centers for Disease Control and Prevention (CDC) is reporting at least 11 confirmed cases of AFM in 2026. In previous years, cases have been associated with increased circulation of Enterovirus D-68 (EV-D68). While no cases of AFM have been identified in Washington this year, wastewater monitoring has indicated increased circulation of EV-D68 in recent weeks.

Actions Requested

To ensure rapid identification of suspected cases of AFM, healthcare providers in Washington are requested to do the following:

IDENTIFY

• Suspect AFM in patients of ANY age who present with:
  • Acute onset of flaccid weakness in one or more limbs, AND

o    MRI showing gray matter lesions spanning one or more spinal segments.

• Consider Polio in the differential diagnosis, especially in patients who are not vaccinated for polio and who have had recent travel to areas with high risk for polio.
• Refer to CDC’s Evaluating Proximal Muscle Weakness to aid in the workup for AFM.

NOTIFY

• Report suspected cases of AFM to within 24 hours.
• Report suspected cases of Polio to IMMEDIATELY.

TEST

• Specimens: Collect CSF, whole stool, respiratory, and serum specimens as soon as possible after onset of limb weakness.
• Refer to CDC’s specimen collection guidance for AFM (PDF) for additional information.
• Contact the Local Health Jurisdiction BEFORE SHIPPING SPECIMENS. LHJ will help arrange shipping to Washington State Public Health Laboratories (PHL): PHL will ship specimens to CDC.

MANAGE

• Closely monitor for respiratory failure in suspected AFM patients, and have a low threshold to admit to the hospital.
• Be aware that care for AFM is mainly supportive. For additional AFM treatment information, visit:
  • CDC: AFM Information for Healthcare Providers
  • AFM Physician Consult and Support Portal
• Confirmation for cases of AFM is completed at the CDC and may take several weeks.
• Infection control: Use Standard + Contact + Droplet precautions, consistent with CDC’s infection prevention recommendations for EV-D68.

Background

AFM is a rare condition that affects the spinal cord, resulting in muscle and nerve weakness similar to the clinical presentation for polio. Although AFM can occur in patients of any age, it mainly affects children. 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; most AFM patients report a history of febrile illness 1–2 weeks before their onset of acute flaccid limb weakness.

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 October 2, 2026, CDC has received 26 reports of suspected AFM, with 11 confirmed cases in 9 states. There have been no cases of AFM reported in Washington for 2026. Increases of reported AFM cases occurred in 2016 and 2018, with 10 and 11 cases reported in Washington, respectively. Since 2019, sporadic cases of AFM have been reported in Washington.

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

For more information about AFM please visit:

• WA DOH: Acute Flaccid Myelitis (AFM) – Notifiable Condition
• CDC: Acute Flaccid Myelitis (AFM)
• CDC: AFM Cases and Outbreaks
• CDC: AFM Information for Healthcare Providers
• AFM Physician Consult and Support Portal

For more information about Polio please visit:

• WA DOH: Polio (poliomyelitis) – Notifiable Condition
• CDC: Clinical Guidance for Investigating a Suspected Case of Polio
• CDC: Polio (Poliomyelitis) Vaccination: Information for Health Care Providers

Contact

Questions?

• For urgent issues, call (253) 649-1412.
• For non-urgent issues, call (253) 649-1413 and leave a message.
  • Includes reporting notifiable conditions 24 hours a day, 7 days a week.
  • Leave the patient’s name, date of birth and disease.