By Gary Evans, Medical Writer
The recent increase of acute flaccid myelitis (AFM) in pediatric patients has parents distraught and investigators looking at more questions than answers. Typical onset includes weakness in the arms and legs, with the median age of afflicted children being four years old.
While some infectious agents are known to cause the condition — Enterovirus (EV)-D68 and EV-A71 — the Centers for Disease Control and Prevention has not been able find a common denominator for the outbreak.
As of Nov. 2, 2018, the CDC reported 80 confirmed cases of AFM in 25 states across the U.S. In addition, another 139 unconfirmed cases are under investigation.
“I am frustrated that despite all of our efforts, we haven’t been able to identify the cause of this mystery illness,” Nancy Messonnier, MD, director of the CDC National Center for Immunization and Respiratory Diseases, said at a recent press conference.
Given the unknowns, is it possible that more cases of AFM are occurring undetected?
“This is actually a pretty dramatic disease,” she said.
“These kids have a sudden onset of weakness. But it is certainly possible that there are people out there who have the disease who haven’t been reported, especially mild disease.”
Indeed, one of the reasons the CDC held the press conference was to get word out to parents to seek medical care immediately if they see signs of limb weakness in their children.
Other symptoms include facial droop, difficulty swallowing, and slurred speech. There is no specific treatment for AFM at present, with physical therapy and other interventions currently handled on a case-by-case basis by neurologists, infectious disease physicians, pediatricians, and other clinicians.
An alarming increase in AFM cases occurred in 2014 and has ebbed and flowed in the years since then. The emergence of AFM in 2014 occurred amid a national outbreak of EV-D68. However, investigators did not consistently detect EV-D68 in all AFM patients, suggesting that something else was causing or contributing to the increase in 2014.
The CDC is casting a wide net in investigating the current AFM cases, looking for risk factors, pathogens, and possible environmental toxins to explain the increase.
“Despite extensive laboratory testing, we have not determined what pathogen or immune response causes arm or leg weakness and paralysis in most patients,” she said. “We don’t know who may be at higher risk for developing AFM or the reasons why they may be at higher risk. We don’t fully understand the long-term consequences of AFM.”
Polio, West Nile Ruled Out
Some patients have recovered completely while others develop chronic paralytic conditions and continue with physical rehabilitation. In this sense, AFM mimics polio in some patients, but the polio virus has not been found in any cases.
“CDC has tested every stool specimen from the AFM patients, and none has tested positive for the poliovirus,” Messonnier emphasized.
The CDC knows too well the history of fear associated with polio, which paralyzed some 15,000 people annually in the early 1950s before the vaccine was available.
Polio has been eradicated in the U.S., but still exists in some parts of the world. West Nile virus also has been linked to AFM in the past, but the CDC said that vector-borne disease also has not been found in the cases under investigation.
“AFM can be caused by other viruses, such as enterovirus, West Nile virus, as well as environmental toxins,” she said.
Cases also have been traced to autoimmune disorders wherein the immune system attacks tissue as if it were a foreign material.
“We’ve detected enterovirus in several of these individual cases,” she explained.
“There’s a long list of other agents that we have found in one or two.”
Still, the etiology of individual cases does not add up to a “unifying diagnosis,” she said.
Partnering with clinicians, the CDC is reviewing MRI scans to see whether unrecognized cases of AFM were occurring before 2014. The agency is working with sentinel sites in active surveillance to detect AFM and respiratory viruses.
Also, AFM clinical guidelines were being updated as this report was filed.
“We know of one death in 2017 in a child that had AFM,” Messonnier said.
“As a parent myself, I understand what it is like to be scared for your child. Parents need to know that AFM is very rare even with the increase in cases that we are seeing now.”
In that regard, if one looks at AFM cases within the total population of those under age 18 in the U.S., the risk is approximately one in a million.
“Ninety percent of the cases are in those 18 years of age or younger,” she said.
Although rare, the unknowns were underscored by the broad recommendations Messonnier gave to parents to protect children. These included handwashing, up-to-date childhood immunizations, and use of insect repellent.
The consensus is that the AFM paralytic symptoms are not communicable in and of themselves. However, some of the viral pathogens that can trigger the condition are infectious, so the CDC is recommending that AFM patients be under standard and contact precautions.
If an enterovirus like EV-D68 is suspected, infection preventionists should ratchet up isolation to include droplet precautions, the CDC recommends.
“Our standard of practice is to isolate patients based on symptoms,” said Sue Dolan, RN, an IP at Children’s Hospital Colorado in Aurora.
“For example, those with respiratory symptoms — regardless of whether they are tested or not for a pathogen — are placed in contact and droplet precautions.”
A past president of the Association for Professionals in Infection Control and Epidemiology, Dolan has been dealing with AFM and the viruses that can cause it for years.
“In pediatrics, staff have very close contact with young patients that are unable to handle their secretions and pose both contact and droplet transmission risks,” she told Hospital Infection Control & Prevention.
“During these outbreaks, out of an abundance of caution, we have isolated any patient admitted with unexplained neurological findings using standard, contact, and droplet precautions.”
In March of this year, Dolan’s hospital began seeing an increase in patients with enterovirus infections who also had neurological complications.
Patient samples were sent to the CDC for testing and were identified as EV-A71, she said.
Any patient with a positive EV culture of cerebral spinal fluid, throat, rectum, or blood must remain on contact and droplet precautions for the duration of their hospitalization, she said.
“We chose to keep these patients on precautions due to the concern for the severity of this disease in some patients,” Dolan said.
“We did not want to take the chance of releasing them from isolation too soon and having them mingle with other patients, for example, in playrooms.”
In addition to acute limb weakness, the telltale sign for AFM is spinal cord lesions detected via MRI.
AFM is now a reportable condition in Colorado, Dolan said, according to the following definition:
- acute focal limb weakness;
- MRI showing a spinal cord lesion largely restricted to gray matter and spanning one or more spinal segments OR cerebrospinal fluid (CSF) with pleocytosis (CSF white blood cell count >5 cells/mm3);
- CSF protein may or may not be elevated.
This definition will be proposed at the annual Council of State and Territorial Epidemiologists meeting in June, and it is expected to be adopted nationally, she said.
Back to Basics
Questions have arisen about the effectiveness of alcohol hand sanitizers on nonenveloped viruses such as EV-D68.
Although these viruses “may be less susceptible to alcohol than enveloped viruses or vegetative bacteria, alcohol-based hand rub offers benefits in skin tolerance, compliance, and, especially when combined with glove use, overall effectiveness for a wide variety of healthcare pathogens,” the CDC notes.1
Wash hands prior to donning and after removal of gloves, using either alcohol rubs or traditional soap and water, the CDC recommends.
“We continue to support and allow both methods at our facility, as our staff are using gloves with these patients as one part of their PPE use,” Dolan said.
“Infection prevention and control practices work,” Dolan said. “A combination of efforts within our facility and with our public health partners has helped to better understand these [AFM] outbreaks and assured that further transmission inside our facility did not occur.”
The key for IPs dealing with this type of situation, Dolan noted, is to look for trends of unusual illnesses, partner with local public health, and raise awareness through communication both locally and nationally.
“Ensure basic infection prevention and control measures are being implemented in a timely and consistent manner,” she said.
“Tweak isolation procedures when pathogens behave in different ways. Limit transmission risk by screening visitors and limiting visitation practices as needed.”
In addition, IPs should make sure their facility is cleaning and disinfecting environmental surfaces and equipment. Adjust infection practices as needed for AFM patients who may have long-term stays for rehabilitation needs, she added.
“Infection preventionists are key players in situations such as this by providing up-to-date expertise and education on routine practices, and reporting communicable diseases and unusual clusters to the health department,” Dolan said. “IPs develop a keen eye for the unusual.”
- CDC. Enterovirus D68 for Health Care Professionals. Oct. 9, 2018: https://www.cdc.gov/non-polio-enterovirus/hcp/ev-d68-hcp.html.