Molecular and Clinical Comparison of Enterovirus D68 Outbreaks among Hospitalized Children, Ohio, USA, 2014 and 2018

Abstract

Enterovirus D68 (EV-D68) causes respiratory tract infections and neurologic manifestations. We compared the clinical manifestations from 2 EV-D68 outbreaks in 2014 and 2018 and a low-activity period in 2016 among hospitalized children in central Ohio, USA, and used PCR and sequencing to enable phylogenetic comparisons. During both outbreak periods, infected children had respiratory manifestations that led to an increase in hospital admissions for asthma. The 2018 EV-D68 outbreak appeared to be milder in terms of respiratory illness, as shown by lower rates of pediatric intensive care unit admission. However, the frequency of severe neurologic manifestations was higher in 2018 than in 2014. During the same period in 2016, we noted neither an increase in EV-D68 nor a significant increase in asthma-related admissions. Phylogenetic analyses showed that EV-D68 isolates from 2018 clustered differently within clade B than did isolates from 2014 and are perhaps associated with a different EV-D68 subclade.

Keywords: EV-D68; Enterovirus D68; Ohio; United States; acute flaccid myelitis; asthma; children; molecular detection; pediatric; viruses.

Figure 1

Sample and patient selection for investigation of EV-D68 outbreaks, Columbus, Ohio, USA. Viral testing was conducted at Nationwide Children’s Hospital Department of Pathology. During May–November 2014, a total of 3,540 samples underwent viral testing, of which 41% tested positive for RV/EV by a single or multiplex PCR. Four hundred fifty-nine samples were selected randomly on the basis of availability, integrity, and amount of specimen, of which 44% were positive for EV-D68. During May–October 2018, a total of 3,633 samples were tested for RV/EV by FilmArray Respiratory Panel v1.7 (6); 1,987 (55%) were positive. Of the 1,025 convenience samples, 401 (39%) were positive for EV-D68. After samples for which clinical data were not available, for which patient age was >21 years, or for which EV-D68 was acquired nosocomially were excluded, 192 case-patients from the 2014 outbreak and 278 from the 2018 outbreak were included in the analyses. EV-D68, enterovirus D68; RV/EV, rhinovirus/enterovirus.

Figure 2

Percentage of EV-D68 (A) and number of admissions for asthma per 1,000 hospital admissions (B) among rhinovirus/enterovirus-positive (RV/EV) samples, Nationwide Children’s Hospital, Columbus, Ohio, USA, June–October 2014, 2016, and 2018. EV-D68, enterovirus D68.

Figure 3

Phylogenetic analysis of EV-D68 from samples from children at Nationwide Children’s Hospital, Columbus, Ohio, USA, 2011, 2014, and 2018. Phylogenetic tree was constructed using partial viral protein 1 gene sequences. Scale bar indicates changes in base substitutions per site. EV-D68, enterovirus D68.

Figure 4

Amino acid analysis of 17 EV-D68 strains from samples from patients at NCH, Columbus, Ohio, USA, 2011, 2014, and 2018. EV-D68 strains represent subclades B1, B2, and B3 were aligned. Black boxes indicate amino acids included in viral protein 1 motifs corresponding to protein loops; colored boxes indicate strains corresponding to each subclade (green, clade B1; blue, clade B2; red, clade B3). GenBank accession numbers are given in parentheses. EV-D68, enterovirus D68; NCH, Nationwide Children’s Hospital.