July 22, 2016
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EV-D68, acute flaccid myelitis linked during 2014 Colorado outbreak

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Children with acute flaccid myelitis had a 10-fold greater risk for having enterovirus D68 infection during a cluster of cases in Colorado in 2014, according to recent CDC findings.

“From Aug. 8, 2014, through Oct. 14, 2014, a cluster of cases of acute limb weakness, cranial nerve dysfunction, or both, in children with characteristic clinical and radiologic findings of myelitis were identified at Children’s Hospital Colorado,” Negar Aliabadi, MD, epidemic intelligence service officer at the CDC, and colleagues wrote. “Although no etiology for the neurologic disease was identified among the Colorado cluster of patients, EV-D68 was found in the nasopharynx of 45% of these patients.”

Researchers from the CDC, Children’s Hospital Colorado and the University of Colorado conducted a retrospective case-control study of children (n = 11) who had been treated at the hospital and another nearby institution for respiratory illnesses. They collected nasopharyngeal specimens for pathogen testing in Colorado within a 2-month period to find a correlation between different upper respiratory diseases and the presence of EV-D68.

Aliabadi and colleagues established two control groups: The first group included children who were treated as outpatients and for whom nasopharyngeal specimens were tested by multiplex respiratory pathogen panel-PCR (RPP-PCR). The second group included outpatients whose nasopharyngeal specimens were collected and tested by PCR for Bordetella pertussis. Case patients aged younger than 21 years with acute neurologic illness, characterized by spinal cord lesion findings by MRI, no identified etiology and focal weakness of one or more limbs, were considered to have acute flaccid myelitis.

The researchers tested two models for comparisons between acute flaccid myelitis and the controls. The first model tested the association between EV-D68 and acute flaccid myelitis, while the second tested the association between enterovirus and rhinovirus only.

Among 203 specimens from ICU patients with acute flaccid myelitis, Aliabadi and colleagues identified 49% that were positive for EV-D68. In addition, acute flaccid myelitis diagnoses peaked and coincided with those of EV-D68 respiratory infections at Children’s Hospital Colorado during that period. No predominant virus was detected in the enterovirus/rhinovirus species.

During the outbreak period, the researchers determined that 13 patients had acute neurologic disease with limb weakness, cranial nerve dysfunction or both. Two, without limb weakness based on CDC definition for acute flaccid myelitis, were excluded from the study. Case patients with acute flaccid myelitis were older than RPP-tested controls (P = .05), and were more febrile compared with controls tested for B. pertussis (P < .001).

“These epidemiologic data, combined with the biological plausibility of this association, suggest a possible causal link; however, a gap remains between the epidemiologic data and the data from extensive testing of laboratory specimens,” Aliabadi and researchers wrote. “Improved surveillance for [acute flaccid myelitis] with timely and comprehensive specimen collection and testing for EV-D68 are needed.” – by Kate Sherrer

Disclosure: The researchers report no relevant financial disclosures.