Acute Flaccid Myelitis (AFM)

Acute flaccid myelitis (AFM) is a rare but serious
condition that affects the nervous system,
specifically the spinal cord, and causes sudden
onset of weakness in limbs (one or more arms or legs)
and loss of muscle tone. Other symptoms may
include facial weakness, droopy eyelids,
difficulty moving eyes, swallowing or speaking.
There are several possible causes of AFM such as
viruses (e.g., poliovirus, other enteroviruses,
adenoviruses, and West Nile Virus),
environmental toxins, genetic disorders, and
some immune-mediated conditions.

Since August 2014, the Centers for Disease Control
and Prevention (CDC) has seen an increase in the
number of reports of AFM in the United States.
Orange County had a few cases of AFM reported in
children in 2016 but has not had any cases in the
past year. Orange County is participating in enhanced
surveillance for acute flaccid myelitis and encourages
clinicians to maintain vigilance for suspect cases.
To report a case, health care providers/facilities
should call Orange County Epidemiology
at 714-834-8180 or fax records to 714-560-4050.

Infographic Source:

Latest News

Increases in AFM have been reported from several different areas of the U.S. in 2018. CDC continues to actively investigate the AFM cases, monitor disease activity and test specimens. For more information on the latest activity:

Acute Flaccid Myelitis Advisory from the California Department of Public Health

Frequently Asked Questions

What are the symptoms of acute flaccid myelitis (AFM)?

People with AFM may initially have symptoms of a viral illness, such as fever, cough, or vomiting and diarrhea. Limb pain and weakness then develop several days later. In addition, some patients may experience:

    · facial droop/weakness

    · difficulty moving eyes

    · drooping eyelids

    · difficulty with swallowing

    · slurred speech

    · numbness or tingling

    · difficulty passing urine

    · respiratory failure, if the muscles involved with breathing become weak

Many cases will have improvement of symptoms over time. But clinical improvement is not universal;
it varies from patient to patient and take months to occur.

How common is AFM?

AFM is a very rare condition with less than one case in a million people in the United States reported every year, even with the recent increase

How is AFM diagnosed?

AFM should be considered when patients present with symptoms of acute onset of limb weakness. Cerebrospinal fluid testing generally will demonstrate pleocytosis (increased white blood cells ≥5 cell/mm3), and magnetic resonance imaging (MRI) findings include a spinal cord lesion largely restricted to gray matter, and spanning one or more spinal segments. Specific infectious etiologies (such as enteroviruses, West Nile virus, rhinovirus, and herpes simplex virus) may be tested for through your health care provider with assistance from the local health department, if indicated, and the patient meets criteria.

Even with aggressive testing, a cause for AFM may not be identified.

How is AFM treated?

Treatment is supportive; no specific treatment for AFM is available.

How can I decrease the risk of getting AFM?

General disease prevention steps are recommended:

    · Keep up to date on vaccinations, including polio vaccine to avoid polio-associated AFM.

    · Protect yourself from mosquito bites by using repellant and removing stagnant water. 
      West Nile virus, which is one cause of AFM, is spread by mosquitoes.

    · Wash your hands often to prevent getting sick and spreading germs in general.

For more information about AFM in general, see the CDC website


Healthcare Professionals

Suspect cases should be reported to Orange County Epidemiology at 714-834-8180 or fax records to 714-560-4050. Specimens on suspect AFM cases that meet criteria may be submitted for testing for specific infectious etiologies through Orange County Public Health. Requested specimens include:

  • CSF (2-3 mL) in cryovial;
  • acute serum, prior to IVIG (2-3 mL) in tiger/red top tube;
  • 2 stool specimens collected 24 hours apart; and
  • nasopharyngeal (NP) and oropharyngeal (OP) swabs in viral transport medium

Specimens should be collected from suspected AFM patients as early as possible in the course of illness.
Pathogen-specific testing should continue at hospital laboratories.

CDPH AFM Quicksheet:

CDC “Acute Flaccid Myelitis: Interim Considerations for Clinical Management”:

CDC AFM Website:


Last reviewed October 15, 2018