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Acute Flaccid Myelitis

​Acute flaccid myelitis (AFM) is a rare but serious condition that affects the nervous system, mostly in children, causing weakness in the arms and legs, and can lead to permanent paralysis. AFM is a medical emergency and patients must be hospitalized and monitored in case they progress to respiratory failure. Since August 2014, the Centers for Disease Control and Prevention (CDC) has seen an increased number of people across the United States with AFM. According to the CDC, viruses, including enteroviruses, play a role in causing AFM.


Sudden onset of arm or leg weakness, loss of muscle tone, and loss of reflexes are the most common symptoms. Some other symptoms that patients may have include:

  • Facial droop/weakness,
  • Difficulty moving the eyes,
  • Drooping eyelids,
  • Difficulty with swallowing or slurred speech,
  • Pain in arms or legs, or
  • Pain in neck or back

Seek medical care right away if you or your child develops any of these symptoms.

AFM in Pennsylvania

The Department of Health is working with the CDC to confirm diagnoses of AFM. As of September 1, 2021, the department is investigating the following cases:

  • 2023 – 1 confirmed case; 0 probable cases and 0 suspect cases
  • 2022 – 0 confirmed cases; 0 probable cases and 0 suspect cases
  • 2021 – 2 confirmed cases; 0 probable cases and 0 suspect cases
  • 2020 - 3 confirmed cases; 0 potential cases
  • 2019 - 1 confirmed case; 1 potential case
  • 2018 - 11 confirmed cases; 0 potential cases
  • 2017 – 1 confirmed case
  • 2016 – 7 confirmed cases
  • 2015 – 0 cases
  • 2014 – 7 confirmed cases

The source of most cases of AFM is unknown, however possible causes may include viruses, environmental toxins and genetic disorders, or an unknown combinations of factors.


There is no specific action to take to prevent AFM. Since most children had a respiratory illness or fever consistent with a viral infection before they developed AFM, it's important to take steps to decrease risk of getting viral infections, including:

  • Washing hands often with soap and water,
  • Avoid touching face with unwashed hands, and
  • Avoid close contact with people who are sick.

To learn more about AFM, visit the CDC’s website.