The CDC reported today that 233 patients in 41 states were affected by acute flaccid myelitis, or AFM, in 2018. Although most of these patients quickly sought care, providers often delayed reporting suspected cases, sometimes for weeks, the agency said.
“Doctors and other clinicians across the United States play a critical role. We ask for your help with early recognition of patients with AFM symptoms, prompt specimen collection for testing and immediate reporting of suspected AFM cases to the health department,” Anne Schuchat, MD, CDC principal deputy director, said in a press briefing. “When specimens are collected as soon as possible after symptom onset, we have a better chance at understanding the causes of AFM, the recurrent outbreak, and developing a diagnostic test. Rapid reporting also helps us to identify and respond to outbreaks early and alert other clinicians and the public.”
The CDC has yet to definitively establish the cause of AFM. Some experts have argued that enterovirus D68, or EV-D68, is the culprit. A task force assigned to investigate AFM in the U.S. has identified priorities that will help to narrow down possible causes of the disease, including strengthening and expanding outreach to health care providers, developing a network for collecting and sharing specimens for lab testing, and conducting studies to better understand why some children develop AFM but most do not.
“The CDC is learning more about AFM through monitoring trends, researching possible risk factors and conducting advanced lab testing and research to understand how viral infections may trigger AFM,” Tom Clark, MD, MPH, deputy director of the CDC’s Division of Viral Diseases, who is leading the agency’s AFM investigation, said in the briefing.
He added that the CDC is collaborating with the NIH to better understand the causes and outcomes of the condition. Additionally, the CDC is conducting advanced surveillance at seven children’s hospitals throughout the U.S., where researchers can study viruses circulating in these areas and how they may contribute to AFM development.
The CDC began tracking AFM in 2014, and since then outbreaks have been detected every 2 years. Similar to previous outbreaks, most cases in 2018 were observed in young children, with an average age of 5 years. Nearly all (98%) children required hospitalization, 60% required admission to ICUs, and 27% required mechanical ventilators to breathe. AFM has also followed a seasonal pattern, with cases spiking between August and October, according to the CDC.
Clark said poliovirus was not detected in stool specimens collected from patients with AFM, although viruses were present in many respiratory and stool samples. Half the samples were positive for enteroviruses — including EV-D68 and EV-A71 — or rhinoviruses. Cerebrospinal fluid was positive for EV-D68 in one patient and positive for EV-A71 in another.
“We really do suspect that viruses play a role, and enteroviruses are among the leading suspects,” he said. “These are really ubiquitous infections that are common in childhood. We have a lot to learn through the research we proposed in understanding what triggers AFM in young children.”
This year, 11 cases of AFM in eight different states have been confirmed, the CDC said. – by Katherine Bortz
Lopez A, et al. Morb Mortal Wkly Rep. 2019;doi:10.15585/mmwr.mm6827e1.
Disclosures: Clark and Schuchat report no relevant financial disclosures.