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State of California—Health and Human Services Agency
California Department of Public Health

September 15, 2022

All Californians

Health Advisory: Vigilance for Acute Flaccid Myelitis (AFM) Warranted - Recent Detections of Enterovirus D68 and Poliovirus in the United States

The California Department of Public Health (CDPH) requests healthcare providers and local health departments to be vigilant for acute flaccid myelitis (AFM), which typically presents with sudden limb weakness in children that can lead to permanent paralysis. Clinicians should consider the diagnosis of AFM in patients with acute onset of flaccid weakness to ensure optimal care.

During periodic surges in AFM before the COVID-19 pandemic, enterovirus D68 (EV-D68) was the most common enterovirus detected among AFM cases, typically in late summer and early fall when enteroviruses tend to circulate. Historically, increases in EV-D68 respiratory disease, including severe disease requiring hospitalization especially in children, have preceded these surges in AFM by several weeks. In August 2022, a similar increase in EV-D68 respiratory disease was detected in sentinel surveillance sites in the United States, including California, thereby warranting increased vigilance for AFM. From January 1, 2022 through September 14, 2022, CDPH has received 11 reports of suspected AFM in persons from California; six have been classified by the Centers for Disease Control and Prevention (CDC) as confirmed cases of AFM. Please see CDC's recent HAN "Severe Respiratory Illnesses Associated with Rhinoviruses and/or Enteroviruses Including EVD68" for more information.

Importantly, with the identification of a paralytic polio case in an unvaccinated person in New York in July 2022, clinicians should consider polio in patients with suspected AFM who are not fully vaccinated against polio AND have either traveled to or had contact with travelers from areas where polio is circulating.

Action steps when suspecting AFM or polio 

Hospitalize the patient immediately:

  • Monitor the respiratory status of patients with acute flaccid weakness, which in AFM can progress rapidly to respiratory failure.
  • Order an MRI of the spine and brain with the highest Tesla scanner available.
  • Consult promptly with specialists in neurology and infectious diseases for diagnosis and management, as signs and symptoms of AFM overlap with other neurologic conditions.
  • Follow CDC's standard, contact and droplet infection control precautions for suspected or confirmed AFM cases.

Report patients of any age suspected to have AFM or polio as soon as possible:

Laboratory testing to maximize detection of possible etiologic agents:

  • Please collect cerebrospinal fluid (CSF), serum, stool (x2), and respiratory specimens (nasopharyngeal or oropharyngeal swabs). The LHD will work with the clinical lab to transfer specimens to the CDPH VRDL.
  • Collect specimens as early as possible after onset, preferably on the day of onset of limb weakness.
  • Continue testing at the hospital laboratory for specific pathogens as clinically indicated.
  • Please do not delay shipping other specimen types to VRDL while awaiting stool specimens, which can take several days to collect.
  • The CDPH AFM Quicksheet contains additional instructions on specimen submittal and shipping, including completion of VRDL General Purpose Specimen Submittal Forms.

For AFM cases, the CDPH VRDL regularly tests cases for SARS-CoV-2, enterovirus (including typing to identify poliovirus), rhinovirus and adenovirus and conditionally for West Nile, St. Louis encephalitis, Zika, dengue, and chikungunya viruses. The timing of results typically precludes their guiding clinical management.

For questions about shipping specimens to the VRDL, call 510-307-8585. For AFM assistance or consultation, call CDPH Immunization Branch at 510-620-3737 or email 

For more information

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