Acute Flaccid Myelitis: Alert for Healthcare Providers

Technical Bulletin from DPBH

Carson City - August 01, 2018

Current Situation:

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. AFM has been under investigation by health departments and the Centers for Disease Control and Prevention (CDC) for the past 4 years. Surveillance has shown us that AFM cases generally peak in the months of September and October. A biennial pattern has been observed, with the majority of cases reported in 2014 and 2016, and smaller numbers reported in 2015 and 2017. If this pattern continues, we should expect to see an increase in AFM cases in 2018. The Division of Public and Behavioral Health (DPBH) encourages physicians to be aware of the symptoms of AFM.

Clinical Description:

AFM appears to start with a prodromal respiratory or gastrointestinal illness about 1 week before limb weakness onset. Pain in the neck or back often directly precedes weakness in one or more limbs, and cranial nerve findings such as slurred speech, difficulty swallowing, and eyelid or facial droop may occur. On exam, the weak limb(s) displays poor tone and diminished reflexes. Cerebrospinal fluid may show a lymphocytic pleocytosis and elevated protein. MRI findings in AFM cases include lesions in the central, or gray matter, of the spinal cord.


If you believe your patient has symptoms of AFM, such as acute flaccid weakness, contact DPBH as soon as possible. In addition, please collect biological specimens for testing as soon as possible to increase the possibility of finding a cause. These specimens can be tested through a hospital or the Nevada State Public Health Laboratory (NSPHL) for enteroviruses, West Nile virus, and other infectious etiologies known to be associated with AFM. At the same time, additional aliquots of CSF, serum, stool, and respiratory samples should be collected and sent to the NSPHL. The NSPHL will coordinate the shipment of specimens to CDC for further testing. It is important this effort is coordinated through DPBH and NSPHL. For a complete list of specimens that can be collected for testing please visit CDC’s AFM website:

Reporting Criteria:

Since AFM is a relatively new condition, DPBH and CDC need information on all patients to help us better understand the spectrum of illness, all possible causes, risk factors, and outcomes for AFM. It is important to send all information about patients that meet the clinical criterion for AFM (sudden onset of flaccid limb weakness) to DPBH at (775) 687-5977. Information should be sent on patients who meet the clinical criterion regardless of any laboratory results or MRI findings. Note there is no age restriction for reporting suspected cases. The case definition includes people of all ages to allow us to collect information on the full spectrum of the condition in both children and adults. For more information about the case definition for AFM, please see


Melissa Peek-Bullock
State Epidemiologist