The headlines of the past several weeks about kids with a polio-like illness have been pretty scary. The idea that a healthy child could suddenly be sidelined with extreme muscle weakness is a nightmare scenario for the parents of young children. While frustratingly little is known about acute flaccid myelitis (AFM), the good news is that it remains quite rare, affecting less than one in a million people in the U.S. each year.

According to the CDC, there have been a total of 404 confirmed cases of AFM in the U.S. since 2014, with a median age of eight years. The epidemiologic curve of cases indicates that the illness is seasonal, peaking in late summer and early fall. Oddly, the number of cases spiked in 2014, 2016, and 2018, while there were fewer cases during 2015 and 2017.

Signs and symptoms of AFM.

AFM often follows a respiratory illness or fever. Limb weakness (often unilateral) then occurs suddenly, progressing rapidly within hours or a few days. There may be facial muscle weakness, problems with eye movement, or speech or swallowing difficulties, but mental status generally is not affected. One death has been reported.

No clear cause.

Poliovirus, non-polio enteroviruses, adenoviruses, and West Nile virus are known to (rarely) cause similar symptoms, but no single pathogen has been consistently detected in cerebrospinal fluid specimens from affected children. No poliovirus has been detected in any of the cases. The initial cluster of cases that drew attention to AFM in 2014 was at first thought to be related to a simultaneous outbreak of severe respiratory illness caused by enterovirus-D68, but that possible connection has been inconsistent.

The CDC conducted a follow-up survey of affected individuals after the 2014 cluster, and received responses from 56 of the identified cases. In most cases there was some improvement in function about four months after the onset of muscle weakness. A few people recovered completely, and a small number described no improvement at all.

Treatment.

There is  no specific treatment for AFM. Early physical and rehabilitative therapy—”as soon as the patient is clinically stable“—may help to prevent muscle atrophy and contractures, and may improve functional outcomes.

Despite intense surveillance since 2014, the CDC emphasizes that we don’t yet know

  • the cause of this illness (though it is likely infectious, and probably a virus);
  • why many cases suddenly appeared in 2014;
  • who is at higher risk for AFM, or what specific risk factors may be involved; or
  • the long-term consequences of AFM.

The nursing role.

As the epidemiology and clinical features of AFM continue to unfold, nurses can contribute to both the ongoing investigation and the management of patients by

  • being vigilant for possible cases;
  • helping to ensure that if AFM is suspected, the clinical team contacts their local or state health department (who in turn connect with the CDC);
  • ensuring (in collaboration with the health department) that specimens are collected as early as possible in order to optimize the chance that a causative organism can be detected (for instructions, see https://www.cdc.gov/acute-flaccid-myelitis/hcp/instructions.html);
  • and expediting physical therapy referral.

More information is available on the CDC’s website, including  the case definition, known epidemiology, directions for specimen collection, and additional treatment guidance: see https://www.cdc.gov/acute-flaccid-myelitis/. Urgent questions related to a possible case of AFM can be directed to the CDC Emergency Operations Center at 770-488-7100. Non-urgent questions can be sent to the AFM experts at the CDC: AFMinfo@cdc.gov.

CDC resources used in this summary:

AFM Investigation: https://www.cdc.gov/acute-flaccid-myelitis/afm-surveillance.html

FAQs: https://www.cdc.gov/acute-flaccid-myelitis/hcp/faqs.html

Interim Considerations for Clinical Management: https://www.cdc.gov/acute-flaccid-myelitis/downloads/Interim-Considerations-AFM.pdf