With increased virus activity, providers urged to be alert for signs of rare polio-like syndrome in kids

Pediatricians and top health officials are warning about an uptick in activity of a common virus that in rare cases can cause a polio-like syndrome in young children.

The virus, an enterovirus known as EV-D68, is one of the bugs that regularly circulates and infects us from time to time, typically just causing colds. But occasionally, children infected with it will develop limb weakness and a progressive form of paralysis, what’s called acute flaccid myelitis, or AFM.

And now, after a pandemic-related break in EV-D68, the virus appears to be roaring back, with health officials concerned it could foreshadow more cases of AFM.

On Friday, the Centers for Disease Control and Prevention issued a health alert to providers that EV-D68 seemed to be at least partially behind an increase in hospitalizations last month among kids with respiratory infections and that the virus seemed to be outpacing other types of cold-causing bugs.

And pediatric infectious disease physicians are urging pediatricians and clinicians at emergency departments and urgent care centers, as well as parents, to be on the lookout for early signs of AFM.

“EV-D68 is back this year and circulating in the U.S.,” said Kevin Messacar, a pediatric infectious diseases specialist at Children’s Hospital Colorado, who warned that in past years, waves of the enterovirus were followed by spikes in AFM. “So 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,” he said.

AFM often first appears as limb weakness, typically as a child is recovering from what looks like a standard cold, sometimes with a fever. Other symptoms include drooping eyelids and trouble swallowing or speaking.

While there are no specific treatments for AFM, hospitals can provide supportive care. Some children recover, but others do not fully regain motor control and require long-term rehabilitation.

Researchers aren’t sure why EV-D68, which tends to peak in the late summer or early fall, sometimes results in AFM, or who may be most vulnerable.

Doctors say they’re telling people to be on the lookout for AFM symptoms because it can progress from limb weakness to serious paralysis within days. One-third of patients need significant respiratory support.

“If their kid is just getting over this cold, and all of a sudden something isn’t working right — whether it’s an arm or a leg — those are the first signs typically,” said Matthew Vogt, a pediatric infectious diseases physician at the University of North Carolina. “You can go from normal to very, very sick in such a rapid period of time, that’s the reason it needs to be recognized so quickly.”

Furthermore, some doctors have been treating AFM patients with drugs that tamp down their bodies’ immune response to the virus, in the belief that an over-active response is what leads to the attack on the neurological system. Though it’s still unclear whether this approach is effective, it needs to be started quickly, Messacar said.

“So that’s another reason that we want people thinking about this so cases get found and diagnosed early so that the treatments that would have a possibility of working are instituted as early as possible,” he said.

It’s only in the past decade that researchers have identified and started tracking AFM, as well as tied it to EV-D68. Waves of EV-D68 — and the subsequent AFM spikes — tend to occur every two years. There were 120 AFM cases in the U.S. in 2014, 153 in 2016, and 238 in 2018. Fewer cases of AFM have been reported in the off years.

But the mitigation efforts imposed to reduce the spread of the coronavirus that causes Covid-19 also dramatically reduced the transmission of other respiratory viruses like EV-D68. That meant there was no wave in 2020 as would have been expected; there were just 33 AFM cases that year.

Experts are watching to see if this EV-D68 wave will turn out to be particularly large. It is thought that the virus appears to circulate on a two-year pattern because it takes that long for the population to build up enough susceptibility to the virus — with people losing immunity and as more children are born — for it to take off. But by essentially skipping a wave, there are likely far more people out there who are susceptible to the virus, including a large swath of children born in the past few years who have yet to be exposed to it.

The CDC’s health advisory suggests there is another reason to be concerned this year may see a significant jump in cases.

Most health care settings that see children suffering from an infection of EV-D68 would run a test that cannot identify the enterovirus specifically. The test result would show the child had been infected with a rhinovirus or an enterovirus. There are many of both and most trigger only mild cold-like illness.

But some laboratories that are part of surveillance networks that feed results to the CDC run more detailed diagnostics on cases like these. Those surveillance sites are currently reporting that a higher proportion of these rhinovirus and enterovirus cases are positive for EV-D68 this year than has been seen in previous years, the CDC alert said.

On a patient level, doctors say it typically takes about a week for a child to start showing neurological symptoms after the onset of respiratory symptoms. But increases in AFM cases start being reported nationally often a month after a surge of EV-D68 has begun. Already, pediatricians are starting to hear that children with AFM are showing up at hospitals.

“Can we prevent these cases? Not currently,” Messacar said. “Do we have an effective medicine that we know works to reverse this? Not currently. But I do think we can do a better job than even in prior years in taking care of these kids and giving them the best chance they can for recovery.”