ATLANTA — CDC researchers reported that nearly all patients with acute flaccid myelitis, or AFM, in 2018 had evidence of viral illness before developing the condition.
“We are working to better understand what causes AFM,” Susannah McKay, PhD, MPH, an Epidemic Intelligence Service officer from the CDC’s Division of Viral Diseases, said during a press conference. “We encourage everyone to do the things you would normally do to keep from getting sick with a virus like washing your hands, avoiding contact with people who are sick and to help prevent others from getting sick by covering coughs and sneezes and staying home when you’re sick.”
McKay added that parents and caregivers should get medical care right away for children who develop sudden limb weakness, and that clinicians should be vigilant for acute flaccid limb weakness and immediately report these cases to state and local health departments.
The researchers examined nationwide reports of patients with limb weakness collected by health departments between Jan. 1 and Dec. 22, 2018. AFM was defined as acute flaccid limb weakness and spinal cord lesions on gray matter identified through MRI. The researchers tested the patients’ specimens for enteroviruses, rhinoviruses and parechoviruses using PCR.
EIS officer Susannah McKay, PhD, MPH, works at her desk in Atlanta.
Cases peaked in September 2018, with 249 patients reporting weakness. Of these patients, 70% had confirmed AFM (median age = 4.9 years), according to the researchers. More than half of the patients were male, and 95% had prior respiratory or febrile illness.
Hospitalization was required for 98% of patients with AFM, and 58% were admitted to an ICU.
When McKay and colleagues assessed the medical charts of 72 patients, they found documentation of symptoms of bulbar weakness, including dysphagia (13%) and dysarthria (8%). More than half (52%) had abnormal brain MRIs, with lesions in the pons (53%) and medulla (39%) that were consistent with bulbar weakness.
Of 121 cases, PCR was positive for enteroviruses in 34% of patients, rhinoviruses in 6% of patients, untyped enterovirus or rhinovirus in 5% of patients, and parechoviruses in 6% of patients. These infections were mostly identified in nonsterile sites.
“There is growing evidence to suggest enteroviruses as a leading etiology for AFM. Nearly all patients reported symptoms consistent with viral illness before developing AFM, and about half of the patients with AFM who had specimens tested at the CDC had evidence of an enterovirus,” McKay said. “However, we know that enterovirus infections are very common, and it isn’t clear why in rare instances that individuals develop AFM. [The] CDC is working hard to get to the bottom of this.” – by Katherine Bortz
McKay SL, et al. Upsurge of acute flaccid myelitis in the United States — CDC surveillance results, 2018. Presented at: Epidemic Intelligence Service Conference; April 29-May 2, 2019; Atlanta.
Disclosure: McKay reports no relevant financial disclosures.