Rare Polio-like Illness to Peak Again This Fall, CDC Warns

Rare Polio-like Illness to Peak Again This Fall, CDC Warns

Amid the pandemic, AFM cases are climbing. Since 2014, the disease has spiked every two years between August and November.

Updated on August 10, 2020 at 1:00pm EDT.

As the United States continues to struggle to control the COVID-19 pandemic, health officials are warning about an expected resurgence of acute flaccid myelitis (AFM) this fall.

AFM is a rare polio-like condition that causes weakness and paralysis in the arms or legs. Since 2014, the disease has peaked every two years between August and November in the U.S., according to the Centers for Disease Control and Prevention (CDC).

AFM is expected to spike once again in 2020, the CDC warns.

Cases already on the rise
As of July 31, there have been 16 confirmed cases this year. Another 38 cases are also under investigation. One person has died from the disease, the CDC reports.

Health officials are asking doctors to be vigilant and promptly report all suspected AFM cases to their local health departments.

“Recognition and early diagnosis are critical,” said CDC Director Robert Redfield, MD, in an August 4 news release. “CDC and public health partners have strengthened early disease detection systems, a vital step toward rapid treatment and rehabilitation for children with AFM."

The condition can progress rapidly over the course of hours or days, leading to more serious complications that require urgent medical care, such as help with breathing. Prompt treatment is critical for better outcomes, the CDC cautions.

Most cases involve children
Most of the people diagnosed with AFM are children. In fact, more than 90 percent of those diagnosed with AFM in 2018 were kids with a median age of about 5 years old. More than 90 percent of these patients also had a mild respiratory illness or fever, suggesting they had a viral infection before they developed AFM, the CDC reports.

Health officials began monitoring the condition back in 2014 after noticing an unusual spike in an illness that caused sudden weakness in the arms and legs. Since then, there have been 633 confirmed cases, or between 22 and 238 diagnoses every year.

AFM cases tend to rise in late summer and early fall. In 2019, there were 46 confirmed cases in 16 states, according to the CDC.

A total of 238 people in 42 states were diagnosed with AFM in 2018—the highest number of confirmed cases since the CDC began tracking the condition in 2014. The severity of the 2018 outbreak caused the rare condition to receive even more attention.

The seemingly mysterious illness captured headlines, fueled concerns among parents and prompted federal health officials to issue warnings about the condition. But what exactly is AFM and how worried should you be?

What is it?
Acute flaccid myelitis is a serious condition that affects the nervous system. People with AFM develop lesions in the gray matter inside their spinal cord. The most common warning signs are sudden weakness in the arms or legs as well as loss of muscle tone and loss of reflexes.

Additional symptoms of AFM may include:

  • Droopy face or eyelids
  • Trouble moving the eyes
  • Difficulty swallowing
  • Slurred speech
  • Trouble breathing
  • Pain in the arms, legs, neck or back

In extreme cases, AFM may cause paralysis. Despite the fact that AFM triggers polio-like symptoms, the CDC points out the confirmed cases of the condition were not caused by the poliovirus.

Searching for clues
For some people, AFM may be particularly concerning because there are still more questions than answers. It’s unclear why AFM appears to be on the rise, what causes it and how it can be most effectively treated.

Back in 2014, there was an outbreak of respiratory illness among kids, many of whom had asthma and other lung disease. This outbreak was caused by an enterovirus, known as EV-D68, which was linked with AFM, explains Christopher Ohl, MD, an infectious disease specialist at Wake Forest Baptist Medical Center in Winston-Salem, North Carolina. As a result, the CDC began monitoring the condition and testing samples of patients’ spinal fluid and blood for evidence of what might be causing the illness. This ongoing investigation could help explain the increasing prevalence of AFM.

“There is a high level of scrutiny and if you’re looking for something, you’re going to find more,” Dr. Ohl says.

Several possible causes
The fact that AFM tends to spike in the late summer and early fall suggests the condition has a seasonal pattern, Ohl adds. The annual resurgence of the condition was also less notable in 2015 and 2017 than it was in 2014 and 2016. Then, cases hit a new high in 2018—in line with this biennial pattern.

Enteroviruses, particularly EV-D68 (a type of virus that causes an illness similar to a cold) and EV-A71 (one of many non-polio enteroviruses) are likely responsible for these peaks in cases, according to the CDC.

Scientists investigating AFM, however, have identified several possible causes, including toxins in the environment and certain viral infections, such as the mosquito-borne illness, West Nile virus. Coxsackievirus A16 (hand, foot and mouth disease) has also been pinpointed as a possible trigger in some patients.

Health officials still haven’t found one clear common link among all AFM cases that fully explains the increasing incidence of the condition. This likely means that there is more than one cause, Ohl says.

How AFM is diagnosed and treated
The warning signs of AFM may be confused with other neurological disorders, such as Guillain-Barre syndrome (GBS), a condition that causes the immune system to attack part of the nervous system.

A neurological exam and an MRI of the brain and spinal cord are needed to confirm an AFM diagnosis. Some patients may also undergo a spinal tap, which is a procedure that involves checking the cerebrospinal fluid for potential pathogens.

The large variety of treatments that have been used to manage AFM—including antiviral and anti-inflammatory drugs as well as drugs to suppress patients’ immune system response—have not been effective. Unlike other parts of the body, which may heal more readily, damaged nerve tissues take much longer to recover, Ohl explains.

While there is not one specific treatment or cure for AFM, doctors may recommend certain therapies for individual patients, including physical or occupational therapy to help them regain mobility or strengthen their arms or legs.

Some AFM patients may face lingering effects for months or even years, but a full or nearly full recovery over time is possible, he says. Scientists are still trying to figure out why some people recover more fully and quickly than others. Some patients may be genetically more susceptible to the condition, Ohl points out.

Should you be worried?
It’s important to remember that AFM is still very uncommon.

“It’s really, really rare,” Ohl says. “It’s sort of like winning the lottery—not very likely.”

In the U.S., it’s estimated that fewer than one in a million people will develop the illness each year. By way of comparison, Ohl points out that there are more deaths, hospitalizations and long-term effects from the flu each year than from AFM.

What can you do to prevent AFM?
AFM is still under investigation but there are some general things you can do to help protect against the viral infections that have been linked to the condition. The CDC recommends taking the following precautions:

  • Make sure you and your children are up to date on your vaccines.
  • Practice good hand hygiene, washing often with soap and water for at least 20 seconds.
  • Don’t touch your face with unwashed hands.
  • Avoid close contact with people who are sick.
  • Clean and disinfect commonly touched surfaces, such as doorknobs and toys.
  • Cover coughs and sneezes with a clean tissue or upper shirt sleeve—not hands.
  • If you notice anyone, particularly a child, experiencing sudden weakness or other symptoms of AFM, you should seek medical attention right away.

The CDC provides more information on its ongoing AFM investigation.

Medically reviewed in August 2020.

Centers for Disease Control and Prevention. “CDC Expects 2020 Outbreak of Life-Threatening Acute Flaccid Myelitis.” August 4, 2020.
U.S. National Library of Medicine. “Acute Flaccid Myelitis.” August 4, 2020.
Centers for Disease Control and Prevention. “AFM Cases and Outbreaks.” July 31, 2020.
Centers for Disease Control and Prevention. “AFM: Frequently Asked Questions by Clinicians and Health Departments.” August 1, 2020.
Centers for Disease Control and Prevention. “Vital Signs: Clinical Characteristics of Patients with Confirmed Acute Flaccid Myelitis, United States, 2018.” August 7, 2020.
Centers for Disease Control and Prevention. “ACUTE FLACCID MYELITIS (AFM) IN CHILDREN. A FACT SHEET FOR PARENTS.” May 19, 2020.
Centers for Disease Control and Prevention. “Symptoms of AFM.” February 25, 2020.
Centers for Disease Control and Prevention. “Causes of AFM.” July 13, 2020.
Centers for Disease Control and Prevention. “Transcript for CDC Telebriefing: Update on Acute Flaccid Myelitis (AFM) in the U.S.” October 17, 2018.

Antibody Testing: Why It’s Not a Guarantee of Immunity to COVID-19
Antibody Testing: Why It’s Not a Guarantee of Immunity to COVID-19
Updated May 11, 2020 at 12:00pm EST. As COVID-19 cases around the world continue to climb and the economic fallout from weeks of lockdown restriction...
Read More
Going Back to the Office? Take These Steps to Help Ensure Your Safety
Going Back to the Office? Take These Steps to Help Ensure Your Safety
Updated June 26, 2020; 3:00pm ET Americans are increasingly returning to the workplace, whether they want to or not. For some employees, furloughs ha...
Read More
Johnson & Johnson’s COVID-19 Vaccine Gets Green Light in U.S.
Johnson & Johnson’s COVID-19 Vaccine Gets Green Light in U.S.
Updated on February 28, 2021 at 6:15pm EST. The Johnson & Johnson (J&J) COVID-19 vaccine has cleared it's final hurdle and is now available in the Un...
Read More
Want to Get Outside? 6 Low-Risk Activities to Try
Want to Get Outside? 6 Low-Risk Activities to Try
Updated on July 28, 2020 at 2:00 PM EDT. With summer in full swing but new cases of COVID-19 resurging in many parts of the country, Americans are lo...
Read More