By Sarah Ovaska-Few
A medical mystery is confounding national medical experts: The increase of a rare polio-like condition in children, where sudden paralysis or weakness of the limbs can set in following an otherwise unremarkable respiratory virus.
Two children in North Carolina came down with confirmed cases of acute flaccid myelitis, or AFM, in 2018 with two additional cases from this year under review, according to the N.C. Department of Health and Human Services. State health officials declined to release additional details about the children’s conditions, locations and ages, citing medical privacy laws.Nationally, there have been 165 confirmed cases of AFM this year that the federal Centers for Disease Control and Prevention are tracking. AFM began appearing in the United States in 2014 but has seen increasing numbers since, with 36 states seeing cases this year. Only one fatality, in 2017, has been linked to the illness, according to Dr. Thomas Clark, an infectious disease researcher at the CDC, in a presentation on the federal agency’s campus to journalists earlier this month.
The CDC launched a new effort this month to understand what’s behind the rise in AFM cases with the formation of a task force that met in early December.
Characterized by a sudden weakness of the limbs, AFM can be incredibly serious for those who contract it, with most children needing to be hospitalized and some in need of ventilators to assist breathing, Clark said.
“Most of the kids have deficits even if they recover some function,” Clark said.
Their long-term prognosis is unclear, given that medical experts don’t know what causes AFM or how to treat it.
“We really don’t know how these kids are doing after AFM,” he said.
AFM affects the part of the spine called gray matter and leads to diminished muscle response. Other symptoms include facial drooping, difficulty moving the eyes, drooping eyelids, difficulty swallowing and slurred speech. While it may resemble the paralysis seen in polio cases, no signs of the polio virus have been found in specimens taken from AFM patients, according to the CDC.
No one yet knows exactly what is causing the disease, said Justin Albertson, an epidemiologist with the state DHHS.
“This is something that’s a little unusual because the cause isn’t known,” Albertson said.
Experts like Clark, Albertson and others are befuddled by why a small number of children are developing AFM after having respiratory viruses that most children recover from easily.
Among the connections medical experts at the CDC are exploring are if there’s a direct infection of viruses on the nerves that move muscles, indirect infections where viruses can trigger inflammatory responses that in turn leads to AFM, or if there’s a genetic connection that leaves some children more susceptible than others.
Here is more of what’s known about AFM, according to Clark and the CDC:
- Nearly all – 95 percent of cases – occur in those under 18.
- The average age of AFM patients is between 5 and 6 years old.
- More than 90 percent of cases were preceded by a respiratory virus or fever.
- Most cases occurred between August and October when many viruses are circulating.
Also perplexing medical experts is a two-year cycle in the number of cases. The disease spikes every other year with 100 to 200 cases seen nationally in one year and only a few dozen in the following years, according to statistics provided by the CDC.
Unknown cause, but AFM remains rare
Parents and caregivers hearing about AFM shouldn’t panic, Albertson said, pointing out that there have only been two confirmed cases in North Carolina’s 600,000-plus children under five this year and fewer than 200 cases nationally.
“The most important thing is for parents to know that AFM is still extremely rare,”
he said. “It really literally is one in a million.”
But for those it does impact, AFM can be a serious illness, with children facing sudden paralysis and, in some cases, lengthy rehabilitation that may or may not lead to recovering mobility in their arms and legs, Clark said.
Clark and others at DHHS will help get specimen samples to the CDC to help scientists there figure out what might cause AFM, as well as determine ways to treat or even prevent it.
But doctors in hospital settings treating children with AFM-like symptoms should treat it as an emergency if there are signs of paralysis, he said. While letting the CDC and local and state health departments know about possible AFM cases is important, it shouldn’t stop doctors from helping their patient.
“Don’t delay treatment based on waiting for a confirmation from the CDC,” Clark said.
His suggestion came despite there being no recommended treatments at this point. Some doctors have used treatments such as corticosteroids, intravenous immunoglobulin treatments or plasma exchange which are helpful in other neurological conditions.
While some in the academic realm including experts at Johns Hopkins University have theorized that it could be related to Enterovirus D68, which is in the same family as the polio virus. Clark said the CDC isn’t yet ready to pinpoint a cause.
“We’re trying to not get ahead of the data,” he said.