Researchers have found new evidence linking acute flaccid myelitis (AFM) to enteroviruses (EVs).
AFM is rare but serious, characterized by sudden limb weakness and typically preceded by respiratory illness or fever. Federal health officials have been trying to pinpoint a cause of outbreaks, the largest of which have been occurring every other year since 2014. While the timing has coincided with outbreaks of EV-D68 and EV-A71, the viruses often aren’t seen in AFM patients’ cerebrospinal fluid (CSF).
In a new study published in mBio, a team from Columbia University and the Centers for Disease Control and Prevention (CDC) studied 13 children and one adult with AFM and five patients with non-AFM central nervous system diseases using viral-capture high-throughput sequencing. Only one patient from each group had enterovirus RNA in their CSF.
“Failure to detect viral RNA in CSF may represent absence of virus, low levels of viral template, or sequence mismatch between viral template and primers or probes,” authors said.
Using the same 14 CSF samples from AFM patients, the team then took a more indirect approach, looking for EV antibodies. They also studied samples from control groups that included children and adults with non-AFM central nervous system conditions and children with Kawasaki disease.
The antibodies were detected in the CSF of 11 of 14 (79%) AFM cases compared to three of 26 (11.5%) in the control group.
“The presence in cerebrospinal fluid of antibodies to EV peptides at higher levels than non-AFM controls supports the plausibility of a link between EV infection and AFM that warrants further investigation and has the potential to lead to strategies for diagnosis and prevention of disease,” authors wrote.
As research continues, public health officials have urged doctors to be on the lookout for AFM. Since 2014, there have been 574 cases, typically occurring in late summer or early fall. Physicians who suspect a patient has AFM should perform a workup, including MRI and collection of respiratory, stool, serum and spinal fluid samples for testing. They also should quickly report suspected cases to their state or local health department.
