Information for Canadians regarding acute flaccid myelitis (AFM)


What is acute flaccid myelitis

Acute flaccid myelitis (AFM) is a term used to describe a specific type of acute flaccid paralysis (AFP), a sudden onset of weakness in one or more limbs. The weakness is a result of inflammation (swelling) of the grey matter of the spinal cord which carries messages to and from the brain.

The condition can be caused by autoimmune diseases or exposure to environmental toxins. It can also be caused by a number of different infections, including enteroviruses or West Nile virus. Sometimes the condition has no known cause.

The long-term effects of AFM can vary. Some individuals with AFM have recovered quickly while others will continue to experience muscle weakness and require ongoing care. Acute flaccid myelitis can affect persons of all ages, however, most of the cases observed since 2014 have occurred in children.

Acute flaccid myelitis is usually diagnosed after a doctor reviews the patient's current symptoms and their medical history. A doctor will use the findings from magnetic resonance imaging, and may order other laboratory tests to confirm the diagnosis.

It is important to seek immediate medical attention if a child, or adult, experiences sudden onset muscle weakness. Other immediate life-threatening conditions, such as stroke, can cause similar symptoms. When in doubt, seek immediate medical attention.


Symptoms of acute flaccid myelitis usually include the sudden onset of weakness in the arms and/or legs or decreased or absent reflexes in the limbs. Occasionally symptoms are accompanied by facial weakness or drooping. Some patients report pain associated with the onset of symptoms.

Reduce your risk

Canadians are advised to reduce their risk by taking the same precautions they would during cold and flu season, including:

  • Frequent handwashing;
  • Avoiding touching their face with their hands;
  • Coughing and sneezing into their arm, and not their hands;
  • Keeping common surface areas clean, such as countertops; and
  • Avoiding close contact with people who are sick and staying home when sick.

Cases of Acute Flaccid Paralysis detected in Canada between January 1, 2018 to February 1, 2021

AFM is a type of acute flaccid paralysis, or AFP. Canada monitors for cases of AFP in children less than 15 years old as a part the World Health Organization surveillance efforts. From 1996 to 2017, there were between 27-63 cases of AFP reported annually in Canada, averaging 44 cases per year.

Table 1: Number of AFP cases detected in Canada between January 1, 2018 and February 1, 2021.Footnote 1
Year Cases Being
Confirmed Cases Total cases
2018 4 72 76
2019 1 35 36
2020 5 22 27



Footnote 1

As of August 2020, cases of the US CDC case definition for AFM is applied to classify cases in Canada.

Return to footnote 1 referrer

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