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acute flaccid myelitis

Acute flaccid myelitis (AFM) is a condition that affects the spinal cord. It is characterized by a sudden weakness in one or more arms or legs, along with loss of muscle tone and decreased or absent reflexes. AFM can be caused by a variety of viruses, including enteroviruses.


The California Department of Public Health (CDPH) reported a statewide increase in acute flaccid myelitis (AFM) in 2016 (PDF) . Clinicians are encouraged to maintain vigilance for cases of AFM among all age groups. CDPH and the Centers for Disease Control and Prevention (CDC) conduct enhanced viral testing and surveillance for patients with AFM. If you are aware of a patient that meets the confirmed or probable case definitions below, please complete the following steps (detailed instructions are also provided in the CDPH AFM Quicksheet (PDF):

  1. Submit the AFM Patient Case Summary Form AND medical records listed on the form to the patient's local health jurisdiction (LHJ).
  2. Obtain approval from the local health jurisdiction (LHJ) for specimen testing.*
  3. After approval has been received, submit specimens with a completed General Purpose Specimen Submittal Form to the CDPH Viral and Rickettial Diseases Laboratory.  Local health jurisdictions will contact CDPH for the appropriate submittal form to submit specimens to CDC.

*Local health jurisdictions will contact CDPH for the AFM Patient Case Summary Form and to receive approval for testing.

Case Definitions


  1. Acute onset of focal limb weakness, AND:
  2. A magnetic resonance image (MRI) showing spinal cord lesion largely restricted to gray matter and spanning one or more spinal segments


  1. Acute onset of focal limb weakness, AND:
  2. Cerebrospinal fluid (CSF) with pleocytosis (white blood cell count >5 cells/mm3, may adjust for presence of red blood cells by subtracting 1 white blood cell for every 500 red blood cells present).
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