Background: In mid-2014, severe respiratory disease associated with enterovirus D68 (EV-D68) was reported in pediatric patients. We studied virologic characteristics and clinical disease due to EV-D68 in patients at Seattle Children's Hospital (SCH).
Methods: Mid-nasal swabs from children with respiratory symptoms were evaluated. A single specimen from each patient with rhinovirus/enterovirus (HRV/EV) detected via commercial multiplex polymerase chain reaction (PCR) platform underwent real-time reverse-transcriptase PCR for EV-D68 using an assay developed in our laboratory. Cycle threshold (CT) was used as a proxy for semi-quantitative viral load. Patient characteristics were compared between EV-D68 pos and EV-D68 neg patients.
Results: From Aug-Dec 2014, 878 patients tested positive for HRV/EV, and 625 had samples available for further testing. 187 (30%) of HRV/EV+ samples tested had EV-D68 detected, an unusually high fraction for a single strain of HRV/EV+ when compared to previous years (11% in 2012, P<0.01). EV-D68 was only detected from Aug. 22-Dec. 18, 2014 (Figure 1). Among our analyzed cohort, 139 (75%) of EV-D68 pos patients were hospitalized prior to or at time of testing vs 232 (57%) of patients positive for HRV/non-D68 EV (p < 0.001). Of those hospitalized, 2 (2%) of patients with EV-D68 required mechanical ventilation (MV) compared to 10 (4%) of patients with HRV/non-D68 EV (P=0.29). Median CT was lower in EV-D68 pos patients requiring MV than those who did not (17.4 v. 25.3, P = 0.04) and between those requiring any supplemental oxygen and those remaining on room air (24.2 v. 26.1, P = 0.05). Median CT did not significantly differ between those with EV-D68 who were and were not admitted to the hospital (25.3 v. 24.9, P=0.2).
Conclusion: Over 30% of pediatric patients positive for HRV/ENT with samples available were infected with EV-D68. Compared to patients with confirmed HRV/non-D68 EV, patients with EV-D68 had a higher rate of hospitalization but no difference in rate of MV. Patients with EV-D68 who required oxygen had lower CT than those that did not, suggesting that viral load may be a marker of clinical severity. Rapid and quantitative testing may help stratify risk; further research is required to understand the pathogenesis of EV-D68.
Figure 1: Frequency of HRV/EV and EV-D68 infections at Seattle Children's Hospital in 2014
H. Chu, None
A. M. Buccat, None
X. Qin, None
J. Englund, Pfizer: Consultant and Investigator , Research grant and Speaker honorarium
Gilead: Consultant and Investigator , Consulting fee and Research support
GlaxoSmithKline: Investigator and Member Data Safety Monitoring Board , Hourly payment for DSMB work and Research support
Alios: Investigator , Research support
Roche: Investigator , Research support
A. Waghmare, None
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