Advice for parents: ‘No reason to panic’ over AFM

Issue: December 2018

The CDC recently announced that the number of acute flaccid myelitis cases under investigation has peaked for the year in the United States. Most cases have been reported in young children. The agency has not yet determined the cause of the disease, known as AFM, which can lead to varying degrees of paralysis of the limbs.

The CDC has been investigating AFM since 2014. At least 299 cases have been reported this year, including 134 confirmed cases in 33 states as of Dec. 3.

Amesh A. Adalja, MD, FIDSA, an infectious disease physician and senior scholar at the Johns Hopkins Center for Health Security, said there is no reason for extreme concern among parents over this rare disease.

“I would advise physicians to tell parents that although AFM is scary and there is a lot of mystery surrounding it, it is still extremely rare,” Adalja said in an interview with Infectious Diseases in Children. “It is not something that you have to worry about every cough or cold or gastrointestinal illness turning into.”

Adalja, who is also a spokesperson for the Infectious Diseases Society of America, said children should seek medical attention if their limbs become weak, “but this is not something that is going to affect every child and it is not something that we see becoming extremely common. There is no reason to panic over this.”

During a recent press conference, Nancy Messonnier, MD, director of the National Center for Immunization and Respiratory Diseases at the CDC, said no deaths were reported among patients with AFM in 2018. She added that the CDC is asking health departments to match their list of patients with AFM against their death registries.

According to an MMWR, most patients have been children aged 2 to 8 years, and about half have been male. Almost all patients reported fever and/or respiratory illness 3 to 10 days before developing limb weakness, Messonnier said. In almost all patients, an upper limb was involved.

In the report, 47.5% of patients with confirmed cases of AFM had upper limb involvement only, 8.8% of patients had lower limb involvement, 15% had two to three upper and lower limbs involved, and 28.8% of patients had involvement of all four limbs.

Messonnier said at least half of patients do not fully recover from AFM.

She noted that the CDC had tested 125 spinal cord fluid, respiratory and stool specimens from confirmed cases. Of the specimens tested, about half were positive for rhinovirus or enterovirus, including EV-A71 and EV-D68. Spinal cord fluid was positive in two patients — one having evidence of EV-A71 and one having evidence of EV-D68. One of the patients was an adult on immunosuppressive medication, and the other was a child who had very rapid progression of paralysis.

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“It is important to put these two cases in context,” Messonnier said. “Since 2014, we have tested spinal cord fluid of most AFM cases, and in only a few have we identified a pathogen. When a pathogen is found in spinal fluid, it is good evidence that it was the cause of the patient’s illness; however, oftentimes, despite intensive testing, no pathogens are found in the spinal fluid.”

This may be because the pathogen has been cleared by the body or it is in hiding in tissues, making it difficult to detect, she said. She added that another possibility is that the pathogen triggers an immune response in the body that causes damage to the spinal cord.

There are currently no targeted therapies or interventions with enough evidence to endorse their use, Messonnier said.

Although the researchers wrote in the MMWR that “clinical, laboratory and epidemiologic evidence to date suggest a viral association,” the CDC reported it is still trying to determine the causes of AFM.

Adalja noted that there is “a lot of mystery” surrounding AFM. “It seems to be that so far, researchers have not been able to find a single cause to understand why this happens,” he said.

Adalja said it appears that all children in the month before developing AFM had either an upper respiratory or GI type of illness, so the leading hypothesis is that certain viruses that cause the common cold and some GI illnesses — primarily enteroviruses — may be the culprit, possibly sparking an autoimmune reaction.

“We do not know what the risk factors are for these children, and why they develop AFM,” Adalja said. “We have seen cases where multiple children in a household get sick, but only one develops AFM. This clearly is something going on between the individual who gets the infection and the virus that is unique to them that causes AFM to occur. Right now, we have seen both enteroviruses D68 and A71 arising to the top list of culprits, but it has not been fully established or elucidated as to how they are able to do that.”

The CDC is working to expedite the process to confirm new AFM cases, but “taking care of the patient is the number one priority for doctors and the health department,” Messonnier said. “We want doctors to treat their patients and consult medical experts, if necessary, without waiting for the classification results.”

CDC director Robert R. Redfield, MD, recently announced the establishment of an AFM Task Force that will aid in defining the cause of AFM and help to improve treatments for patients.

The task force, which will include experts from the scientific, medical and public heath fields, will make key recommendations to the CDC’s Office of Infectious Diseases’ Board of Scientific Counselors.

Adalja told Infectious Diseases in Children that he believes the CDC is doing a good job with its research and getting the word out to the public about AFM.

“The CDC has held frequent press calls, and they just formed a special task force, so I do think that they are doing a lot, but it is hard sometimes in the face of a mysterious illness that is grabbing headlines,” Adalja said. “Parents always want to have more information, and that is sometimes not how science works. It takes some time to figure these mysteries out and unravel it all.” – by Bruce Thiel

References:
CDC. AFM Investigation. https://www.cdc.gov/acute-flaccid-myelitis/afm-surveillance.html. Accessed November 29, 2018.
CDC establishes AFM Task Force. https://www.cdc.gov/media/releases/2018/p1119-cdc-establishes-afm-task-force.html. Accessed November 29, 2018.
McKay SL, et al. MMWR Morb Mortal Wkly Rep. 2018;doi:10.15585/mmwr/mm6745e1.

For more information:
Amesh Adalja, MD, FIDSA, can be reached at aadalja1@jhu.edu.
Nancy Messonnier, MD, can reached at nar5@cdc.gov.

Disclosures: Adalja and Messonnier report no relevant financial disclosures.