Acute Flaccid Myelitis (AFM)

AFM Basics

Disease Description

  • Symptoms

    Acute flaccid myelitis (AFM) is a form of acute flaccid paralysis (AFP), which causes weakness in the arms and/or legs [1]. Other types of AFP include Guillain-Barre syndrome, toxic neuropathy, and muscle disorders [1]. Additional symptoms of AFM can include: facial droop/weakness, difficulty moving the eyes, drooping eyelids, or difficulty with swallowing or slurred speech [2].

  • Causes

    There is no known single cause of AFM, and causes can include viral infections, environmental toxins, and genetic disorders [2]. Viruses associated with AFM include: polio and non-polio enteroviruses, West Nile virus, Japanese encephalitis virus, Saint Louis encephalitis virus, herpesviruses, and adenoviruses [2]. Sometimes, despite extensive laboratory testing, the cause of a patient’s AFM cannot be identified [2].
  • Prevention

    There is no single, specific cause of AFM. However, since AFM can develop as a result of a viral infection, The Georgia Department of Public Health recommends parents and children take basic steps to avoid infections and stay healthy including making sure you and your family are up to date on your vaccinations, protecting yourself from insect bites, and washing your hands often.

Information for Health Professionals


Clinical Features and Epidemiology

  • AFM in the United States

    The Centers for Disease Control and Prevention (CDC) has requested states provide information on suspect AFM cases since the fall of 2014, when clusters of pediatric cases with AFM were identified in Colorado and Kansas [3]. At the same time, there was an ongoing nationwide outbreak of Enterovirus D68 (EV-D68), though not enough evidence exists to determine any causal relationship between the EV-D68 outbreak and AFM cases occurring at that time period [3-4].  In fall 2014, a CDC health advisory was issued requesting that cases consistent with AFP in children younger than 21 years olda be reported and specimens submitted for testing [3]. From August 2014 to December 2014, CDC verified reports of 120 children in 34 states who developed AFM [4]. In 2015 there were 22 confirmed AFM cases reported from 17 states [4]. In 2016 there were 149 confirmed AFM cases reported from 39 states [4]. In 2017, 33 confirmed AFM cases were reported to CDC, and 80 confirmed cases from 25 states have been reported from January 1, 2018 –November 2, 2018 [4]. There is no known single etiology or epidemiologic cause for the AFM cases reported in the US since 2014 [4].
  • AFM in Georgia

    Since August 2014, 12 cases of AFM have been reported to the Georgia Department of Public Health, with ages ranging from 6 months – 17 years at weakness onset. Establishing routine surveillance for AFM in Georgia is necessary to determine the burden of this syndrome and establish baseline incidence. Suspect cases of AFM reportable to DPH are classified according to the following criteria:

Case Definition

  • Clinical Criteria: An illness with onset of acute flaccid limb weakness
  • Confirmed case: Clinically compatible case AND MRI showing spinal cord lesion largely restricted to gray matterb,c and spanning one or more spinal segments
  • Probable case: Clinically compatible case AND CSF showing pleocytosis (white blood cell count >5 cells / mm3).

Laboratory Testing

Specimens should be collected from patients suspected of having AFM as soon as possible, ideally on the day of limb weakness onset. Requested specimens include:

  • Cerebrospinal Fluid (CSF)
  • Blood serum
  • A nasopharyngeal swab
  • Stool
    • Two stool specimens collected as soon after onset of limb weakness as possible and separated by 24 hours

For detailed instructions visit the CDC’s webpage on AFM specimen collection. DO NOT ship specimens directly to CDC, call your local health department to coordinate shipment to the Georgia Public Health Laboratory, who will then coordinate testing and shipping with CDC.


aThe clinical case definition for AFM was changed to include all ages, as opposed to only those occurring in patients ≤21 years old, in August 2015 [3]

bSpinal cord lesions may not be present on initial MRI; a negative or normal MRI performed within the first 72 hours after onset of limb weakness does not rule out AFM.

cTerms in the spinal cord MRI report such as “affecting mostly gray matter,” “affecting the anterior horn or anterior horn cells,” “affecting the central cord,” “anterior myelitis,” or “poliomyelitis” would all be consistent with this terminology.

Case Counts

Report Year Number of AFM Cases*
Reported AFM Cases in Georgia
2014 1
2015 1
2016 5
2017 1
2018** 6

*Includes Confirmed or Probable AFM cases

**Preliminary Case Count


  1. Revision to the Standardized Case Definition for Acute Flaccid Myelitis [Internet]. Council of State and Territorial Epidemiologists; 2017. Retrieved from: [Accessed August 10, 2018]
  2. About Acute Flaccid Myelitis [Internet]. Centers for Disease Control and Prevention; 2018. Retrieved from: [Accessed August 10, 2018]
  3. Standardized Case Definition for Acute Flaccid Myelitis [Internet]. Council of State and Territorial Epidemiologists; 2015. Retrieved from: [Accessed August 10, 2018]
  4. AFM Investigation [Internet]. Centers for Disease Control and Prevention; 2018. Retrieved from: [Accessed August 10, 2018]

Additional Resources