Acute Flaccid Myelitis Cases Increase Following Recent Washington State Outbreak

As health officials investigate a recent outbreak of acute flaccid myelitis in Washington State, more cases of the rare condition have appeared in other Western states; questions about the cause remain unanswered.

*Updated on 11/17/2016 at 9:14 AM EST

Outbreaks of rare conditions always heighten concerns around the world, particularly when they affect young children. Now a recent outbreak of acute flaccid myelitis (AFM) cases affecting children in Washington state has health officials and parents on alert.

On November 4, the Washington State Department of Health announced the launch of a joint investigation after reporting that nine children from five of the state’s counties were admitted to Seattle Children’s Hospital with AFM. Doctors found that eight of the children had the rare condition.

According to the Centers for Disease Control and Prevention (CDC), AFM is a “polio-like” condition of the nervous system that targets the spinal cord. It typically begins with symptoms such as fever and respiratory illness before weakness in the limbs and loss of muscle tone sets in. Individuals with AFM may present with drooping in their face and eyelids, have difficulty moving their eyes, issues with swallowing, and slurred speech. In severe cases, respiratory failure can occur due to weakness in breathing-related muscles.

“At this time, there is not one simple answer for the question of how long the symptoms of weakness and paralysis may last,” pediatrician Janell Routh, MD, a medical officer in the CDC’s Division of Viral Diseases, told Contagion. Based on the information CDC has collected to date, we know that some patients recover function in a shorter period of time than others. Some patients may continue to have symptoms and need rehabilitation services.”

Health experts have linked a variety of common viral infections—such as enteroviruses (polio and non-polio), West Nile virus, and adenoviruses–to AFM, though it is often hard to pinpoint the cause. The Washington State Department of Health also notes that autoimmune disorders and environmental toxins may also lead to AFM, and that in most cases, the cause is never identified. AFM’s symptoms of limb weakness and neurological illness can mimic other conditions, and so, doctors examine the nervous system and the symptoms of a patient, sometimes using magnetic resonance imaging (MRI) scans in order to make a diagnosis. As of September of this year, there have been 89 cases of AFM in 33 states across the United States in 2016, according to the CDC, and though that’s a marked increase since 2015, the number is still below the 2014 total which spiked in September of that year due to an outbreak in Colorado. Most of the patients in recent years have been children.

“At this point there isn’t evidence that would point to a single source of illness among these cases,” said Dr. Scott Lindquist, state infectious disease epidemiologist at the Department of Health. “If more information becomes available, we’ll keep the public informed.”

Of the eight children recently hospitalized with AFM, two are still in the hospital, according to Department of Health officials in Washington. Three possible new cases are currently under investigation. “Patient safety is our top priority at Seattle Children’s, and parents should know that it is safe to bring their children to the hospital,” said Dr. Mark Del Beccaro, chief medical officer at Seattle Children’s Hospital, in the recent press release. “We are using appropriate standard infection control, including putting patients with symptoms of active respiratory infections in isolation so they do not have contact with any other patients.”

The cases in Washington come as other cases have been reported recently in New Mexico, Oregon, and Idaho. In each of those states, health officials have reported standalone cases in children and have yet to find evidence of a larger outbreak, such as the one under investigation in Washington. “We have tested many different specimens from the patients for a wide range of pathogens (germs) that can cause AFM,” says Dr. Routh of the ongoing work of the CDC. “To date, we have not consistently detected a pathogen in the patients’ spinal fluid; a pathogen detected in the spinal fluid would be good evidence to indicate the cause of AFM since this illness affects the spinal cord.”