Overview

Acute flaccid myelitis (AFM) is an illness characterized by acute onset of flaccid limb weakness and magnetic resonance imaging (MRI) showing lesions in the gray matter of the spinal cord.

About Acute Flaccid Myelitis

Most AFM cases have arm and/or leg weakness coupled with loss of muscle tone and reflexes. Additionally, some cases have facial/eyelid drooping, difficulty swallowing, slurred speech, difficulty moving their eyes, and/or pain in their arms and legs.

AFM activity peaks in the late summer and early fall and nationwide outbreaks have occurred on a biennial (i.e., every other year) basis since 2014. As of January 3, 2020, there have been 603 confirmed AFM cases reported to the Centers for Disease Control & Prevention (CDC), including 16 cases from Illinois.

While the cause of AFM has not been identified, it is hypothesized that a viral agent (e.g., enterovirus D68) is involved, as almost all (90%) AFM cases had a preceding respiratory illness and/or fever, increased incidence of AFM cases typically coincides with EV-D68 outbreaks, and viral agents (e.g., EV-D68, EV-A71, Coxsackievirus A16) have been detected in the spinal fluid of a small number of AFM cases.

For more information on acute flaccid myelitis, visit the dedicated CDC and IDPH webpages.

On October 9, 2020 CSTE updated it's position statement. Below is a summary of the updates that were made to the CSTE AFM position statement. Changes include:

  1. Adding explicit language to include laboratory/imaging criteria for suspect cases 
    1. Criteria for case ascertainment now includes acute onset of flaccid limb weakness AND an MRI showing a spinal cord lesion in at least some gray matter 
    2. Suspect case classification has been modified to include supportive laboratory/imaging criteria (MRI showing a spinal cord lesion in at least some gray matter) 
       
  2. Adding case ascertainment criteria to allow for the consideration of potential AFM cases identified post mortem 
    1. Criteria for case ascertainment now includes any person whose death certificate lists AFM as a cause of death or a condition contributing to death 
       
  3. Adding language to allow for the inclusion of persons with evidence of myelitis on autopsy as AFM cases 
    1. Criteria for case ascertainment now includes autopsy findings that include histopathologic evidence of inflammation largely involving the anterior horn of the spinal cord 
    2. Confirmed classification criteria is revised to also include persons who died and did not have an MRI but has evidence of myelitis on autopsy

Reporting & Lab Information

Case Definition, Reporting, And Specimen Collection/Submission Guidelines
Reminder
Clinicians should continue to be vigilant and report all patients under investigation that meet the clinical criteria for acute flaccid myelitis (i.e., sudden onset of flaccid limb weakness) to the Chicago Department of Public Health (CDPH) regardless of any laboratory results or MRI findings.

AFM Case Definition, 2020

In 2020, the CDC updated the AFM case definition, which is used to ensure consistent and accurate case classification for surveillance purposes. All patients under investigation for AFM will receive final classification by a team of expert neurologists.

Clinical Criteria: 

An illness with onset of acute flaccid weakness of one or more limb

Laboratory Criteria:

  • Confirmatory laboratory/imaging evidence: MRI showing spinal cord lesion with predominant gray matter involvement and spanning one or more vertebral segment (excluding lesions caused by physician diagnosed malignancy, vascular disease, or anatomic abnormalities)

  • Presumptive laboratory/imaging evidence: MRI showing spinal cord lesion where gray matter involvement is present but predominance cannot be determined (excluding lesions caused by physician diagnosed malignancy, vascular disease, or anatomic abnormalities)

Case Classification:

  • Confirmed
    • Clinically compatible case with confirmatory laboratory/imaging evidence, AND
    • Absence of a clear alternative diagnosis attributable to a nationally notifiable condition
  • Probable
    • Clinically compatible case with presumptive laboratory/imaging evidence, AND
    • Absence of a clear alternative diagnosis attributable to a nationally notifiable condition
  • Suspect
    • Clinically compatible case, AND
    • Available information is insufficient to classify case as probable or confirmed
Reporting and Specimen Collection/Submission Guidelines

If you have a patient under investigation (PUI) with acute onset of flaccid weakness in one or more limbs:

1

Collect specimens as close to the onset of limb weakness as possible and store according to the table below:

2

Contact the Chicago Department of Public Health (CDPH) via the CDPH Reportable Disease Hotline at 312-743-9000.  A CDPH representative will provide you with an authorization number that you will need for specimen submission to the Illinois Department of Public Health (IDPH).

3

Complete the CDC Patient Summary Form  (Instructions). Also gather the MRI report and the MRI images. Send a copy of these documents to CDPH. Note that another copy will need to go to IDPH with your specimens for testing.

4

Complete the IDPH Communicable Diseases Laboratory Test Requisition Form. On the top of the form, write the authorization number that was provided to you by CDPH.

5

Complete one CDC Specimen Submission Form (also known as the CDC 50.34 Dash Form) per specimen. When completing the form, select "Human" in the "Specimen origin" drop down at hte top left of the form. Select "Enterovirus Detection and Identification" for the "Test order name" field. Enter "CDC-10312" in the "Test order code" field.  Reminder: If you are submitting multiple specimens, you must complete one form per specimen.

6

Ship specimens, along with the CDC Patient Summary Form, IDPH Communicable Disease Laboratory Test Requisition, and the CDC Specimen Submission Form(s), to:  

Illinois Department of Public Health Laboratory
Attn: Virology
2121 W. Taylor Street
Chicago, IL 60612

IDPH Lab Contact Phone Number: 312-793-4760

7

If you are a clinician or infection control practitioner with access to enter reportable diseases into the Illinois National Electronic Disease Surveillance System (I-NEDSS), please enter the case’s information into the system’s AFM module. Note: Clinicians or infection control practitioners interested in becoming I-NEDSS users must first register for an IDPH Web Portal account.

Last updated: January 29, 2020

AFM Symptoms

AFM is characterized by a sudden weakness in one or more limbs, often accompanied by loss of muscle tone and decreased reflexes. In addition, some patients may have:

  • Facial droop/weakness
  • Difficulty moving the eyes
  • Drooping eyelid(s)
  • Difficulty with swallowing or slurred speech

Resources - Acute Flaccid Myelitis

Alerts & Communications

AFM Webinar For Clinicians (Dr. Sue Hong, Lurie Children's Hospital, Fall 2020, on behalf of Illinois AFM Learning Collaborative)

Date

Title

Source

Type

August 2019

AFM SIREN Alert

IDPH

PDF

May 2019

AFM Update

CDC

Website

September 2018

Acute Flaccid Myelitis in the United States: 2015-2017

CDPH

PDF

AFM Reporting

For Clinical Questions or to Report Suspect Cases, Contact:

The CDPH Disease Reporting Hotline at 312-743-9000 

*After hours, weekends, and holidays, call 311 and ask for the communicable disease physician on-call (or 312-744-5000 if outside the City of Chicago)

When to Report

Clinicians should continue to be vigilant and send information to Chicago Department of Public Health (CDPH) for all patients under investigation (PUI) with sudden onset of neurologic illness associated with limb weakness that meet the case definition for Acute Flaccid Myelitis. Clinicians should send information for PUIs who meet the case definition regardless of any laboratory results.

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AFM Contacts

CDPH Disease Reporting Hotline

312-743-9000