Acute Flaccid Myelitis (AFM)- What You Need to Know

By Larry K. Kociolek, MD, MSCI, Division of Infectious Diseases, Associate Medical Director of Infection Prevention and Control

News reports of the new, mysterious illnesses can be very frightening for parents and healthcare providers alike. Acute flaccid myelitis, or AFM for short, is an illness that has been around for a long time. What is new and mysterious about AFM is that we have seen an increased numbers of AFM cases in the United States over the past several years, and we don’t yet know the exact reason why.

What Is AFM?

AFM is a rare but serious condition that affects the spinal cord. Inflammation in the spinal cord can result in sudden weakness of muscles. AFM may present with limb weakness, drooping of the face or eyelids, or difficulties swallowing or talking. Severe cases of AFM may affect the diaphragm muscle, which may result in the inability to breathe adequately without support from a ventilator.

If you or your child develops any of the symptoms associated with AFM that are described above, you should seek medical care right away. 

How Common Is AFM?

AFM is very rare. Since 2014, the Centers for Disease Control and Prevention (CDC) has been investigating reports of increasing numbers of AFM. The CDC has confirmed 22-149 AFM cases per year since 2014. As of October 29th, there have been 72 confirmed AFM cases in the US in 2018. The CDC has not yet confirmed any suspected cases of AFM in Illinois in 2018, but 13 suspected cases in Illinois have been referred to the CDC. Even with this recent increase in cases, the CDC estimates that AFM occurs in fewer than 1 in a million people in the United States. 

What Causes AFM?

There are many infectious and non-infectious causes of AFM. The exact cause of the recent increase in numbers of AFM cases is not yet known. Some proposed viral causes of AFM include enteroviruses, adenoviruses, and West Nile virus. Because many patients with AFM test negative for infectious diseases, the link between AFM and infection remains unproven.

Why Do News Reports Refer to AFM as a “Polio-Like” Illness?

Many of us are too young to have lived through poliovirus outbreaks in the US. In the early 1950’s, poliovirus caused thousands of cases of AFM each year.  However, AFM caused by poliovirus was eradicated in the US by widespread polio vaccination. There have not been any cases of polio acquisition in the US since 1979, and the last case of polio in the US from a foreign traveler was in 1993. Importantly, the CDC has not identified poliovirus in any patients with AFM in this current outbreak. Thus, poliovirus is NOT a suspected cause of AFM in the current AFM outbreak.

What Can I Do to Prevent AFM?

Because AFM may be caused by viruses, you can prevent viral illness through general practices to prevent illness, such as hand washing and avoiding close contact with other sick people. West Nile virus can be prevented by avoiding mosquito bites. 

What Is Lurie Children’s Doing to Combat AFM?

Our infectious diseases and infection prevention specialists are diligently working with Lurie Children’s healthcare providers to quickly identify possible cases of AFM. Cases that are suspicious for AFM are promptly reported to our local health departments, who then report these suspicious cases to the CDC for further investigation. The CDC makes the final determination of whether or not a patient is confirmed to have AFM.

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