the CDC said in a telebriefing.
Acute flaccid myelitis (AFM) is defined as acute, flaccid muscle weakness that occurs less than 1 week after a fever or respiratory illness. Viruses, including enterovirus, are believed to play a role in AFM, but the cause still is unknown. The disease appears mostly in children, and the average age of a patient diagnosed with AFM is 5 years.
“Doctors and other clinicians in the United States play a critical role,” Anne Schuchat, MD, principal deputy director of the Centers for Disease Control and Prevention, said in the telebriefing. “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 health departments.”
While there is no proven treatment for AFM, early diagnosis is critical to getting patients the best care possible, according to a Vital Signs report released today. This means that clinicians should not wait for the CDC’s case definition before diagnosis, the CDC said.
“When specimens are collected as soon as possible after symptom onset, we have a better chance of understanding the causes of AFM, these recurrent outbreaks, and developing a diagnostic test,” Dr. Schuchat said. “Rapid reporting also helps us to identify and respond to outbreaks early and alert other clinicians and the public.”
AFM appears to follow a seasonal and biennial pattern, with the number of cases increasing mainly in the late summer and early fall. As the season approaches where AFM cases increase, CDC is asking clinicians to look out for patients with suspected AFM so cases can be reported as early as possible.
Since the CDC began tracking AFM, the number of cases has risen every 2 years. In 2018, there were 233 cases in 41 states, the highest number of reported cases since the CDC began tracking AFM following an outbreak in 2014, according to a Vital Signs report. Overall, there have been 570 cases of AFM reported in 48 states and the District of Columbia since 2014.
There is yet to be a confirmatory test for AFM, but clinicians should obtain cerebrospinal fluid, serum, stool and nasopharyngeal swab from patients with suspected AFM as soon as possible, followed by an MRI. AFM has unique MRI features , such as gray matter involvement, that can help distinguish it from other diseases characterized by acute weakness.
In the Vital Signs report, which examined AFM in 2018, 92% of confirmed cases had respiratory symptoms or fever, and 42% of confirmed cases had upper limb involvement. The median time from limb weakness to hospitalization was 1 day, and time from weakness to MRI was 2 days. Cases were reported to the CDC a median of 18 days from onset of limb weakness, but time to reporting ranged between 18 days and 36 days, said Tom Clark, MD, MPH, deputy director of the division of viral diseases at CDC.
“This delay hampers our ability to understand the causes AFM,” he said. “We believe that recognizing AFM early is critical and can lead to better patient management.”
In lieu of a diagnostic test for AFM, clinicians should make management decisions through review of patient symptoms, exam findings, MRI, other test results, and in consulting with neurology experts. The Transverse Myelitis Association also has created a support portal for 24/7 physician consultation in AFM cases.
SOURCE: Lopez A et al. MMWR Morb Mortal Wkly Rep. 2019;68:1-7 .