CDC seeks cause of acute flaccid myelitis as cases spike
MelissaJenco, News Content Editor
Federal health officials have confirmed 62 cases of acute flaccid myelitis (AFM) in
22 states this year, most of which have been in children.
The Centers for Disease Control and Prevention (CDC) is investigating an additional
65 cases of the rare but serious disease that is characterized by sudden muscle weakness.
A common thread linking the cases has not been found.
“We’re certainly escalating our response this year to make sure we’re basically considering
everything possible and doing everything we can,” said Nancy Messonnier, M.D., director
of the CDC’s National Center for Immunization and Respiratory Diseases.
MRI showing spinal cord lesion largely restricted to gray matter spanning one or more
vertebral segments (confirmed case) or cerebrospinal fluid with pleocytosis (probable
Among the 62 confirmed cases, 90% are under age 18, and the average age is 4 years.
Officials expect the case count to continue to grow since reporting and verification
take time to complete. The spike is similar tothose in 2016 and 2014, years that saw
149 and 120 cases, respectively.
Still, chances of getting AFM are less than one in a million, according to Dr. Messonnier.
She recommends people protect themselves from illness by washing their hands, staying
up to date on vaccines and wearing insect repellent. Anyone who experiences sudden
weakness or loss of muscle tone should seek immediate medical attention.
Pediatricians and hospitalists should be vigilant and consider AFM if they see a patient
with those symptoms. Patients also may present with a droopy face or difficulty swallowing
“It’s important, particularly in this season where we’re seeing more cases, that this
is thought of as a possibility so that a proper diagnostic workup can happen,” said
Kevin Messacar, M.D., FAAP, a pediatric infectious disease physician and researcher
at Children’s Hospital Colorado and the University of Colorado.
The CDC is continuing to investigate the causes of AFM.In 2014, the uptick in cases occurred during an outbreak of enterovirus D68 (EV-D68),
but not all patients had the virus. Other viruses, environmental toxins and genetic
disorders also potentially can cause AFM.
This year, enteroviruses and rhinoviruses have been among the causes identified in
patients, while none have tested positive for poliovirus or West Nile virus. Although
causes have been identified for some individual cases, there hasn’t been a common
thread that would explain the spike this year.
“There is a lot we don’t know about AFM, and I’m frustrated that despite all of our
efforts we haven’t been able to identify the cause of this mystery illness,” Dr.Messonnier said. “We continue to investigate to better understand the clinical picture
of AFM cases, risk factors and possible cause of this increase in cases.”
In Colorado, 11 of 15 AFM cases have been linked to enterovirus A71 (EV-A71), according
to the state health department. Colorado also experienced cases tied to EV-D68 in
“I think amongst the long list of things that can cause this, the non-polio enteroviruses
seem to be the driving predominant factor in what we’ve seen over the last (four)
years,” Dr. Messacar said.
Since 2014, there have been advances in understanding AFM, including animal models
showing D68 can cause spinal cord infection leading to paralysis and studies looking
at long-term outcomes. Those with AFM linked to EV-A71 this year are recovering more
quickly than those whose disease was tied to EV-D68 in 2014, Dr. Messacar said. Some
of the earlier patients have experienced ongoing disability.
He hopes to see work continue on prevention and treatment. EV-D68 vaccine studies
are in early stages, and there is no consistently effective treatment for AFM.
“Rather than panic,” Dr. Messacar said, “I think this should drive us to action to
say this has happened every other year (in recent years) . What can we be doing to
prepare if this comes back?”