Health care providers and public health experts are watching for a resurgence of a rare paralytic disease that most commonly affects children.
Earlier this month, the US Centers for Disease Control and Prevention warned clinicians that it had seen an uptick in children infected with a virus known as enterovirus D68. The virus typically causes cold and respiratory symptoms but has been linked with the rare paralytic condition known as acute flaccid myelitis, or AFM. The CDC asked health workers to strongly consider that patients who have weakness or paralysis following a respiratory illness or fever might have AFM.
“We’re at the point that there are, and will be, more cases, but we don’t know how many,” said Dr. Leslie Benson, assistant professor at Harvard Medical School and a pediatric neurologist at Boston Children’s Hospital.
Acute flaccid myelitis is a serious neurological condition of the spinal cord that causes muscle weakness, and is primarily seen in children and adolescents. While many patients improve, full recovery is unusual, and paralysis can be so severe that it leads to weakness in the muscles needed for breathing and swallowing.
The illness is rare. Since the CDC began tracking the figures in late 2014, there have been 21 cases in Massachusetts and 693 nationally. This year, there have been 14 confirmed cases of AFM in nine states as of Sept. 14, and none in Massachusetts. Enterovirus D68, also called EV-D68, is thought to peak between late summer and early fall.
According to the health alert, CDC surveillance picked up higher numbers of children testing positive for EV-D68 this past summer, compared with the previous three summers.
With increases in EV-D68 typically preceding cases of AFM, clinicians in Massachusetts and beyond are on the lookout for new instances of paralysis in children.
“I’ve reached out to my colleagues in New England and the surrounding area to raise that awareness and let people know what [tools] we have to take care of these kids if and when they do present, as well as improve our research on the disease so we can learn and improve our ability to take care of these kids,” Benson said.
Surveillance of EV-D68 has increased since 2014, when it caused a nationwide outbreak of severe respiratory illnesses that was followed by over a hundred cases of AFM. More clusters of AFM occurred in 2016 and 2018, also following EV-D68 outbreaks.
COVID mitigation measures likely interrupted EV-D68 transmission, and there have been fewer cases of AFM since 2018.
However, the increase in viral cases is a red flag for clinicians, some of whom are concerned that the pediatric population may be more susceptible to illness this year. COVID protections mean children might not have been exposed to as many other enteroviruses as in the last two and a half years, reducing their immunity to this type of virus.
“That may produce more transmission and we may see more patients with AFM,” said Dr. Carlos A. Pardo, director of the Johns Hopkins Myelitis and Myelopathy Center and a leading member of the Acute Flaccid Myelitis Working Group — set up in response to the 2018 outbreak.
The working group has been diligently preparing for another surge of cases since 2018, bringing together multi-disciplinary teams from institutions across the country and Canada, as well as families impacted by AFM. Teams have outlined criteria to more quickly identify and treat patients earlier in the disease. The group has also outlined approaches for managing patients in the hospital and for improving research.
The working group has also collaborated closely with the National Institutes of Health to understand more about the virus and whether other viruses may lead to AFM.
Work on treatments is ongoing. Teams from Vanderbilt University Medical Center and the School of Medicine of The University of North Carolina at Chapel Hill — in partnership with biotech companies ZabBio and KBio — are awaiting FDA approval to begin clinical trials on a monoclonal antibody that could target the virus to halt destruction of critical cells in the spinal cord.
“We are also thinking even if it can’t reverse damage that has already happened, it can halt new, further damage from occurring,” said Dr. Matthew R. Vogt, an assistant professor at UNC School of Medicine, and a lead researcher on the monoclonal antibody. “In truth, the way to find out is by trying at this point, as we have put the monoclonal antibody through extensive preclinical safety tests with great results to date.”
While there is currently no proven treatment for AFM, for now clinicians are using intravenous immunoglobulins, an antibody treatment usually given to those with weakened immune systems.
The resurgence of the virus comes as polio concerns have begun mounting in New York, London, and Israel. While the threat is similarly focused on pediatric paralysis, polio is a different virus, and clinicians note there is a working and available vaccine for polio to prevent infection and paralysis.
No such vaccine exists for AFM. Benson said that there has been some research suggesting that it is possible to create a vaccine that protects against the virus. Yet vaccine developers would need to weigh the relative rarity of the illness with the potentially devastating effects of it.
Some clinicians, such as Pardo, see a vaccine as a necessity.
“Think about the possibility of 200 kids in a year having this disease,” Pardo said. “This is a catastrophic disease. Paralysis leads to a wheelchair the rest of their life that will require a lot of commitment and resources. 200-300 patients that can be prevented by a vaccine, it’s worth it.”
As clinicians remain on alert, they are encouraging parents to harness many of the same strategies they used for COVID, including hand washing and keeping sick kids home.
Knowing about the possibility of the virus can also help parents be on the lookout for startling symptoms.
“If anything seems like it’s more than a common cold, [parents should] get their kids checked out quickly and not delay if they are worried,” Benson said.