Acute Flaccid Myelitis (AFM) by Amara Zafar, B.S. MPH. Houston Health Department

Acute Flaccid Myelitis (AFM) Falls under the umbrella of Acute Flaccid Paralysis. Clinical Case Definition: An illness with onset of acute focal limb weakness. Multiple etiologic agents may cause acute flaccid myelitis. AFM specifically involves the gray matter, or motor neurons, of the spinal cord. AFM is also most commonly associated with poliovirus but there may be other causes from different viral pathogens including: Non-polio enteroviruses (for example enterovirus (EV) 71), flaviviruses like West Nile virus or Japanese encephalitis virus, herpesviruses, and adenoviruses.

AFM Clinical Presentation Patients with AFM present with acute focal limb weakness, frequently two to three weeks after a respiratory or febrile illness. They may also have facial droop, diplopia, dysphagia, or dysarthria. AFM is identical in clinical presentation to the illness caused by poliovirus and affects the same region of the spinal cord.

Case Classifications by Council of State and Territorial Epidemiologists (CSTE) Case Classifications Confirmed Probable Patient with acute onset of focal limb weakness And an MRI showing a spinal cord lesion largely restricted to gray matter and spanning one or more spinal segments. Patient with acute onset of focal limb weakness And cerebrospinal fluid (CSF) with pleocytosis [white blood cell (WBC) count >5 cells/mm3]

States with confirmed cases of AFM, 2016 AFM Surveillance - 2016 Confirmed None DC WA OR CA NV ID MT UT AZ WY CO NM ND SD NE KS OK TX MN IA MO AR LA WI IL IN OH KY TN MS AL GA FL SC NC VA WV PA MD NY NJ ME VT NH CT RI AK HI States with confirmed cases of AFM, 2016 MI MA DE From January through December 2016 – 136 people in 37 states were confirmed to have AFM. Median age: 5.2 years (range 5 months-61 years)

AFM Surveillance—Continued… 2014: 120 confirmed cases of AFM nationwide, 3 in Texas The data shown here, published by the CDC, represents national data from over 30 states including Texas. AFM first came into the national spotlight in 2014, after a nationwide outbreak of 120 confirmed cases of AFM. 3 cases of AFM were confirmed in Texas, with 117 other cases originating from 33 other states. This initial outbreak occurred at the same time as a nationwide outbreak of enterovirus D-68. EVD68 is a respiratory disease that typically causes mild symptoms. 6

AFM Surveillance—Continued… 2015: 21 confirmed cases of AFM nationwide, 0 in Texas In 2015, there were zero confirmed cases of AFM in Texas. Nationally, there were 21 confirmed cases from 16 states. 7

AFM Surveillance Continued… 2016: 136 confirmed cases of AFM nationwide, 10 (approximately) in Texas. In 2016, through the month of October, there have been 10 confirmed cases of AFM in Texas. Nationally, there were 108 total confirmed cases of AFM, reported from 36 states, including Texas. 8

Importance of Reporting CDC is re-emphasizing the importance of continued vigilance by clinicians for cases of AFM among all age groups. As we enter enterovirus season, it is unclear if an increase of AFM could occur again this year. Therefore, continued vigilance and testing of specimens is needed to help clarify a cause and determine the frequency of AFM. Clinicians are urged to report cases of AFM, irrespective of enterovirus status. Reporting of cases will help local health departments, states and CDC monitor potential increases in this illness and better understand potential causes, risk factors, and preventive measures or therapies.

Resources for Clinicians and Health Professionals Job Aid for Clinicians—How to send information about a suspected AFM case to the health department. Ensure that patient meets confirmed or probable case definition for acute flaccid myelitis (AFM). Contact your local health department when you identify a suspect case of AFM. Coordinate with health department to send information about suspect AFM cases and ship specimens to CDC. Flyers and tools on CDC’s AFM website to distribute—e.g. How to Spot Symptoms of AFM, Fact Sheet for Patients etc. For more information on acute flaccid myelitis, visit: www.cdc.gov/acute-flaccid-myelitis.

Job Aid for Clinicians How to report a suspect AFM case Ensure that patient meets confirmed or probable case definition for acute flaccid myelitis (AFM).

Proposed Changes to AFM Position statement for 2017 Addition of “flaccid” to clinical description – “Acute onset of flaccid limb weakness” Clarification for case classification procedures – “To provide consistency in case classification, review of case information and assignment of final case classification for all suspected AFM cases will be done by experts in national AFM surveillance. This is similar to the review required for final classification of paralytic polio cases” Clarification on presence of lesions for case classification – “Spinal 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”

Sources/References Center for Disease Control and Prevention. https://www.cdc.gov/acute-flaccid-myelitis/index.html “Evaluation of AFM surveillance system”; Hall Noemi, Texas Department of State Health Services.

Questions? Amara.Zafar@houstontx.gov 832-393-4566