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

Health Update

TO: Healthcare Providers and Local Health Jurisdictions

Stay Alert for Acute Flaccid Myelitis in Late Summer and Early Fall

8/6/2026

Key Messages

CDPH urges clinicians and local health departments to remain vigilant for acute flaccid myelitis (AFM), which presents as sudden limb weakness usually in children and can lead to permanent paralysis.

Increased summer travel and gatherings may elevate circulation of respiratory pathogens, including enterovirus D68 (EV‑D68), a virus previously associated with AFM surges.

Although AFM and EV‑D68 activity remain low in 2026, providers should stay alert for potential increases in EV‑D68 respiratory disease and subsequent AFM cases.

Clinicians should also consider poliovirus in patients with sudden limb weakness and obtain whole‑stool samples, especially when patients are under‑vaccinated or unvaccinated.

Background

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, usually in children, and can lead to permanent paralysis.

This summer and fall, increased travel, large gatherings, and events are expected across the country. These activities may result in increases in circulating respiratory pathogens, including enteroviruses. Enterovirus D68 (EV-D68) is believed to be the main virus responsible for substantial increases in AFM cases observed during 2014, 2016, and 2018. Similar patterns in EV-D68 and AFM cases have not been seen in 2020 and later even though there were some increases in EV-D68 detections in the United States last year.

In 2026, the number of reported cases of AFM remain low in the nation and California. As of July 8, 2026, CDC has confirmed seven cases in five states, two in California. In the past years, increases in EV-D68 respiratory disease have preceded cases of AFM by about 2 weeks. Healthcare providers are encouraged to maintain vigilance for both increases in EV-D68 respiratory disease and AFM throughout the summer and early fall.

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 action is particularly important if the patient is under-vaccinated or unvaccinated against polio.

Recommendations

If AFM or polio is suspected, healthcare providers should:

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:

Contact the local health department (LHD) as soon as possible if AFM is suspected. If polio is suspected, contact the LHD immediately by phone.
Submit an AFM Patient Summary Form (available in the CalREDIE document repository), MRI reports of the brain and spine, neurology consultation notes, and laboratory test results.

Contact specimens for laboratory testing to maximize detection of possible etiologic agents:

Collect cerebrospinal fluid (CSF), serum, stool (x2, 24hrs apart), and respiratory specimens (nasopharyngeal and 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.
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 Specimen Forms.

CDPH VRDL regularly tests suspect AFM cases for 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 or email VRDL.submittal@cdph.ca.gov. For AFM assistance or consultation, call CDPH immunization Branch at 510-620-3737 or email VPDreport@cdph.ca.gov.