Enterovirus D68 Infection in Children with Acute Flaccid Myelitis, Colorado, USA, 2014

Abstract

During August 8, 2014-October 14, 2014, a total of 11 children with acute flaccid myelitis and distinctive neuroimaging changes were identified near Denver, Colorado, USA. A respiratory prodrome was experienced by 10, and nasopharyngeal specimens were positive for enterovirus D68 (EV-D68) for 4. To determine whether an association exists between EV-D68 infection and acute flaccid myelitis, we conducted a retrospective case-control study comparing these patients with 2 groups of outpatient control children (1 group tested for acute respiratory illness and 1 for Bordetella pertussis infection). Adjusted analyses indicated that, for children with acute flaccid myelitis, the odds of having EV-D68 infection were 10.3 times greater than for those tested for acute respiratory infection and 4.5 times greater than for those tested for B. pertussis infection. No statistical association was seen between acute flaccid myelitis and non-EV-D68 enterovirus or rhinovirus infection. These findings support an association between EV-D68 infection and acute flaccid myelitis.

Keywords: Colorado; United States; acute flaccid myelitis; acute flaccid paralysis; children; enterovirus infections; enterovirus-D68; myelitis; viruses.

Figure 1

Pathogens isolated from patients with acute flaccid myelitis and from patients in a pediatric intensive care unit, Colorado, USA, July–November, 2014. Box indicates study period. AFM, acute flaccid myelitis; CoV, coronavirus; EV, enterovirus; HMPV, human metapneumovirus; RPP, respiratory pathogen panel; RSV, respiratory syncytial virus; RV, rhinovirus.

Figure 2

Results of enterovirus testing among case-patients and controls in study of acute flaccid myelitis, Colorado, USA, July–November, 2014. Arrows indicate specific strains identified in those specimens; numbers in parentheses indicate number of that type of strain. AFM, acute flaccid myelitis; BP, Bordetella pertussis; CV, coxsackievirus; echo, echovirus; EV, enterovirus; HRV, human rhinovirus; RPP, respiratory pathogen panel; RV, rhinovirus; RPP, respiratory pathogen panel.

Figure 3

Sequencing results for 203 specimens from patients in a pediatric intensive care unit, Colorado, USA, 2014. All respiratory pathogen panel–positive samples were sent to the Centers for Disease Control and Prevention for further testing. Of these, 148 were positive by EV RT-PCR and 55 were negative by pan-EV RT-PCR. The 148 specimens positive by pan-EV RT-PCR were tested by EV-D68 real-time RT-PCR, and of these, 100 were positive (EV-D68). The remaining non–EV-D68 specimens were sent for molecular sequencing and were identified as 26 various HRVs, 4 echoviruses, and 3 CVs; 16 specimens were not typeable. One specimen was co-infected with HRV and CV. CV, coxsackievirus; EV, enterovirus: HRV, human rhinoviruses; RT-PCR, reverse transcription PCR.