July 22, 2019 03:27 pm News Staff – As the late summer/early fall "season" for acute flaccid myelitis nears, the CDC is reminding medical professionals what they should look for to quickly recognize AFM symptoms and report all suspected cases to their health department.
Early recognition and reporting are critical to providing patients with appropriate care and rehabilitation and an overall better understanding of AFM, according to a new CDC Morbidity and Mortality Weekly Report and accompanying Vital Signs report released online July 9.
The agency said most patients with AFM are previously healthy children (median age about 5) who had respiratory symptoms or fever consistent with a viral infection less than a week before they experienced limb weakness. Because AFM can progress quickly from limb weakness to respiratory failure requiring urgent medical intervention, rapidly identifying symptoms and hospitalizing patients are of paramount importance.
"The CDC continues to pursue the definitive cause and mechanisms that define this disease, and we sincerely appreciate the important contributions of the AFM Task Force in helping us get closer to critical answers," said CDC Director Robert Redfield, M.D., in a news release. "I urge physicians to look for symptoms and report suspected cases so that we can accelerate efforts to address this serious illness."
As the late summer/early fall "season" for acute flaccid myelitis nears, the CDC is reminding medical professionals what they should look for to quickly recognize AFM symptoms and report suspected cases to their health department.
Most patients with AFM are previously healthy children who had respiratory symptoms or fever consistent with a viral infection less than a week before they experienced limb weakness.
In an analysis of confirmed cases in 2018, the CDC said it detected enteroviruses and rhinoviruses in 44% of respiratory and stool specimens.
The agency started tracking AFM in 2014, when the first outbreak of 120 confirmed cases occurred. The next outbreak happened in 2016, with 149 confirmed cases, and the third arose in 2018, when 233 patients in 41 states were confirmed as having AFM. To date, AFM cases have largely followed a seasonal and biennial pattern, spiking between August and October every other year.
In an analysis of confirmed cases in 2018, the CDC said it detected enteroviruses and rhinoviruses in 44% of respiratory and stool specimens from affected patients. Of the 74 cases in which cerebrospinal fluid specimens were collected, only two were positive for enteroviruses (EV-A71 and EV-D68).
For public health surveillance purposes, a confirmed case of AFM was defined as acute flaccid limb weakness in a patient with magnetic resonance imaging evidence of a spinal cord lesion largely restricted to gray matter and spanning one or more spinal segments.
Upper limb involvement only was more prevalent in confirmed cases (42%), as was report of respiratory symptoms or fever (92%) within four weeks preceding limb weakness onset. Median intervals from onset of limb weakness to hospitalization, MRI and reporting to CDC were one, two and 18 days, respectively.
Among patients with confirmed AFM in 2018, the CDC said the median intervals between antecedent illness (i.e., febrile, respiratory and/or gastrointestinal) and onset of limb weakness (five days), between onset of limb weakness and hospitalization (one day), and between limb weakness onset and CSF collection (two days) were similar to intervals seen during the 2016 outbreak (five days, one day, and three days, respectively).
Timing of respiratory specimen collection improved in 2018 compared with 2016, but still occurred a median of about three days after the onset of limb weakness and five days after the onset of any respiratory illness, the MMWR noted.
The agency said its scientific staff and other researchers are continuing to investigate how enteroviruses, including EV-D68, might initiate AFM. All 2018 specimens tested negative for poliovirus, a related enterovirus that can cause AFM.
"Our thorough investigation of AFM will help lead to more answers about this severe disease," said Tom Clark, M.D., M.P.H, deputy director of the CDC's viral disease division, in the release. "We are monitoring AFM trends and the clinical presentation, conducting research to identify possible risk factors, using advanced lab testing and research to understand how viral infections may lead to AFM, and tracking long-term outcomes of AFM patients."
And finally, although studies on treating AFM still haven't been systematically evaluated for effectiveness, the CDC, in consultation with subject matter experts from a range of disciplines, has developed interim considerations for the management of patients with AFM. Note that this guidance doesn't indicate a preference for or against any commonly employed treatments for AFM, including intravenous immunoglobulin, steroids and plasmapheresis.