Colorado and the rest of the country skipped a projected increase in a polio-like illness affecting mostly kids in 2020, but doctors are concerned it may make up for lost time this year.
Acute flaccid myelitis, or AFM, a rare condition where kids develop muscle weakness or paralysis following what looks like a cold, had followed a pattern of surging every two years since 2014.
It didn’t return as expected in fall 2020, likely because precautions to stop COVID-19 also reduced infections with EV-D68, a respiratory virus that is one of the major causes of AFM, said Dr. Sam Dominguez, a pediatric infectious disease physician at Children’s Hospital Colorado. Other common viruses can also cause the syndrome.
Since fewer kids got infected with EV-D68 than expected in 2020, that means a larger pool of people is susceptible this fall, Dominguez said. While the vast majority of kids who get the virus recover without complications, if more kids get infected, more would be expected to develop AFM, he said.
Essentially, the cases that were expected in 2020 could be shifted back two years.
“The fact that fewer people were exposed (in 2020), there are more people that can be exposed,” he said. “Thankfully, acute flaccid myelitis is still a relatively rare disease.”
On Friday, the Centers for Disease Control and Prevention sent an alert to health care providers about an increase in hospitalizations with EV-D68. More kids have been coming to Children’s with respiratory illnesses lately than is typical for this time of year, but there’s no routine test for EV-D68, so it’s not clear how many have that particular virus, Dominguez said.
So far, cases of acute flaccid myelitis haven’t increased above their background level, though increasing EV-D68 infections raise the possibility they will in the coming weeks. The CDC has confirmed 13 cases so far this year, none of which were in Colorado.
The first sign of AFM is typically unexplained weakness in one or more limbs, typically after a child had a cold. Some children have problems with their facial muscles, like drooping eyelids or difficulty speaking or swallowing. Unexplained muscle pain can also be an early warning sign, Dominguez said.
Though the symptoms of AFM can resemble polio, EV-D68 isn’t closely related to polioviruses. It’s not clear why a small percentage of kids who get it develop weakness or paralysis, and researchers are studying whether those who do share some genetic predisposition, Dominguez said.
There’s no vaccine or specific treatment for EV-D68 or acute flaccid myelitis, but children whose condition is flagged early tend to do better, Dominguez said. The main treatment is intravenous immunoglobulin, an antibody product that can tamp down inflammation and may fight the virus. But research is ongoing on whether that’s the best option, he said.
“We need more data on how to treat these kids,” he said.
In 2018, there were 238 cases of AFM paralysis nationwide and 16 in Colorado, which was the highest number recorded in a single year. It’s possible more children had it in 2014, though, since public health agencies weren’t looking for EV-D68 or AFM at the start of the year.
EV-D68 has been around since at least the 1960s, when it was discovered in California, Dominguez said. No one knows if the virus changed, or if something happened in the human population that made a large number of kids susceptible at the same time, he said.
“We’re not really sure what happened in 2014,” he said. “But we also weren’t looking for it very well before 2014.”
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