Mysterious paralysis in children now associated with novel enterovirus

Since August 2014, at least 118 children in 34 states have developed sudden paralyzing weakness in one or more limbs. Fever and respiratory illness usually occurred before their neurologic symptoms. Most children were hospitalized, and MRI scans showed inflammation of the gray matter in the spinal cord.

Health officials were caught by surprise. This mysterious neurologic illness, termed acute flaccid myelitis, coincided with an outbreak of severe respiratory illness caused by enterovirus D68 (EV-D68) in 2014. Thus, EV-D68 became the prime suspect.

However, a recent report points to a new culprit—a novel enterovirus, C105.

In a case report released in late June 2015, pediatricians at the University of Virginia School of Medicine, Charlottesville, described a 6-year-old girl who developed acute progressive weakness of her right hand and a droop in her right shoulder. Four days earlier, she had experienced low-grade fever, headache, fatigue, and intermittent pain.

They diagnosed her with acute flaccid myelitis and began testing for enterovirus.

MRI showed swelling of the gray matter in the cervical spinal cord. Nasopharyngeal swab testing was positive for enterovirus C105—the first report of this virus in the United States.

EV-D68 vs. EV-C105

Although health officials have been investigating enterovirus D68 as the prime suspect in the outbreak of acute flaccid myelitis, the link between this virus and the mysterious neurologic illness has been admittedly tenuous.

For one, EV-D68 is similar to rhinoviruses that cause respiratory infections, yet rhinoviruses are not associated with systemic disease, and virus replication is limited to the respiratory tract, the authors noted in their case report.

Also, although most of the children diagnosed with acute flaccid myelitis had experienced respiratory illness, EV-D68 was detected by nasopharyngeal swab in only 20% of patients tested.

Enterovirus C105, on the other hand, has more in common with the polioviruses, which can cause flaccid paralysis.

Cerebrospinal fluid testing would provide the strongest evidence that either virus is directly linked to the illness, but no enterovirus has been detected in the spinal fluid of children involved in this outbreak.

“Although cases of flaccid paralysis associated with isolation of EV-D68 from spinal fluid have been reported, the role of EV-D68 in the current outbreak remains to be determined,” the authors wrote in their case report. “As the results from this case indicate, it is possible that other viral pathogens with neurovirulence may be contributing to the outbreak.”

That is, the authors could not rule out that this patient had a co-infection of both C105 and D68—or other unknown pathogens.

Currently, there are no approved treatments for this illness. In this particular case, the girl was given IV immunoglobulin, but her weakness and pain neither worsened nor improved during her hospital stay. After discharge, her pain spontaneously resolved and, at her most recent follow-up visit (8 months after onset of illness), her arm strength was almost fully restored.

While this particular case report is concerning, it’s a unique one—so there’s no need for panic, said Ronald Turner, MD, professor of pediatrics at UVA and the lead investigator of this patient’s case.

“Most isolates of this [EV-C105] virus have been associated with mild respiratory disease,” Dr. Turner said, adding that this single case doesn’t suggest that the virus is or will be widespread. “The purpose of the case report was more to alert the scientific community and diagnostic labs about this observation.”

In that regard, the Centers for Disease Control and Prevention advises health care providers to report to their state or local health department any patient who shows these symptoms.