Virus Linked With Rare Polio-Like Condition in Children on the Rise, CDC Warns

The number of children hospitalized with severe respiratory illness increased in August, partially due to the spread of an enterovirus, said the Centers for Disease Control and Prevention (CDC) in a health alert last week. Other enteroviruses cause polio and hand, foot and mouth disease.

This virus, known as EV-D68, typically causes only mild cold symptoms. But in rare cases, it can lead to a polio-like condition in young children called acute flaccid myelitis (AFM), report Stat News’ Andrew Joseph and Helen Branswell.

AFM causes muscle and limb weakness and can lead to long-term or permanent paralysis, per the CDC. Other symptoms include drooping eyelids and trouble swallowing or speaking.

Health officials are concerned that a surge in EV-D68 could be followed by a rise in AFM cases, per Stat News. Still, it won’t be any massive wave of illness, experts say.

“[AFM] is exceptionally rare even during an outbreak, so it’s not something that should necessarily keep everyone up at night,” Matthew Elrick, an AFM expert at the Kennedy Krieger Institute, tells ABC News’ Jade Cobern. “But if your child has an illness and was recovering and is now getting worse again, or not behaving in the way that you might expect the normal recovery from illness to be, that’s a good reason to go see the pediatrician and sort out what’s going on.”

As of September 2, there have been 13 confirmed AFM cases in the United States this year, and the CDC is investigating 20 other possible infections. Since 2014, the agency has recorded 692 confirmed cases of AFM. More than 90 percent of these have been in young children, according to the CDC.

A national outbreak of EV-D68 in 2014 led to expanded monitoring of the virus, and subsequent spikes in cases have been coming every two years, in the late summer and fall, writes Ars Technica’s Beth Mole. But the expected surge in 2020 never came as people isolated during the start of the Covid-19 pandemic.

“We really thought this was going to happen in 2020, because we had the last spike in 2018,” Sarah Hopkins, a pediatric neurologist at Children’s Hospital of Philadelphia, tells NBC News’ Aria Bendix. “But then with mask-wearing and social distancing and all those things that limit the spread of a respiratory virus, we didn’t have that expected spike.”

Since it’s now been four years since the last spike, there are likely more people susceptible to the virus, making a jump in cases more likely, writes Stat News. “We have a group of kids now who’ve never seen the virus, because they weren’t having school exposures,” Benjamin Greenberg, a neurologist at UT Southwestern’s O’Donnell Brain Institute, tells NBC News. “So we think the at-risk population is bigger than in 2020.”

The CDC issued this health alert to get these medical conditions on people’s radars. “We want providers, first-line health care workers, pediatricians, ER docs to be on the lookout for cases of patients presenting with weakness, knowing that this is circulating, so that those cases can be diagnosed quickly and managed appropriately,” Kevin Messacar, a pediatric infectious diseases specialist at Children’s Hospital Colorado, tells Stat News.

Adults are typically not affected by EV-D68, per Ars Technica. It’s thought to be more common in adults with underlying conditions, according to the CDC.

There are no specific treatments for respiratory illness caused by EV-D68, per the CDC, nor are there any specific treatments for AFM, per Stat News.

“[AFM] can be very severe and it can be very scary for the parents of children who have it,” Rick Malley of the division of infectious disease at Boston Children’s Hospital tells Medscape's Lucy Hicks. “But given the prevalence of enteroviruses in the community, you have to conclude it’s a relatively rare event in susceptible individuals. Why some get it and others don’t is unfortunately unclear at this moment.”

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Will Sullivan is a science writer based in Washington, D.C. His work has appeared in Inside Science and NOVA Next.