Enterovirus D68 Returned in 2018: Surveillance in Children’s Hospitals

Enterovirus D68 (EV-D68) was rarely reported to CDC before the fall of 2014, when it caused a nationwide outbreak of acute respiratory illness. Reported detections usually peak in late summer and early fall. But its patterns are poorly understood: clinical testing has seldom been available, and cases don't have to be reported to CDC.

To fill that gap, CDC set up active EV-D68 surveillance among children at the seven medical centers of the New Vaccine Surveillance Network (NVSN) — in Cincinnati, Houston, Kansas City, Nashville, Pittsburgh, Rochester (New York) and Seattle. This report compares July 1–October 31 in 2017 and 2018.

How it worked

Children under 18 were enrolled if they came to the emergency department or were admitted with acute respiratory symptoms — such as fever, cough, congestion, sore throat, wheezing or trouble breathing — lasting less than 14 days. Nasal or throat swabs were tested for EV-D68 by real-time RT-PCR. Nashville and Pittsburgh tested every specimen directly; the other five sites first tested for enterovirus/rhinovirus and then tested the positives for EV-D68.

Two very different years

In 2018, 242 of the 358 children with EV-D68 (67.6%) were hospitalized; by site, the share ranged from 53.3% to 76.8%. Detections peaked in September.

EV-D68 detections by date and surveillance site, July–October 2018. Credit: Centers for Disease Control and Prevention.

Share of children tested who had EV-D68 in 2018, by site:

At the five sites that screened first for enterovirus/rhinovirus, 27.6% of the positives in 2018 turned out to be EV-D68 — compared with two of 715 (0.3%) in 2017. European countries also reported EV-D68 activity in 2018.

The link to acute flaccid myelitis

EV-D68 usually causes respiratory illness, but earlier investigations suggested it may also be linked to acute flaccid myelitis (AFM), a rare neurologic condition that causes sudden limb weakness. AFM reports rose at the same time as the 2014 EV-D68 outbreak, and CDC has tracked AFM with a standardized case definition since 2015.

As of March 1, 2019, CDC had confirmed 223 AFM cases in 2018, with limb weakness peaking in September 2018 — compared with 35 confirmed cases in 2017. Together with the EV-D68 surge seen in NVSN, that adds to the evidence of a timing link between EV-D68 respiratory illness and AFM. CDC and its partners continue to investigate the relationship between AFM and enteroviruses, including EV-D68.

Limitations

• Testing covered only July–October; more 2018 cases likely occurred outside that window.
• The seven sites are geographically varied but may not represent every U.S. region.

Continued active surveillance, the authors conclude, is needed to understand how EV-D68 circulates in the United States.

Sources

Based on Kujawski SA, Midgley CM, Rha B, et al., "Enterovirus D68–Associated Acute Respiratory Illness — New Vaccine Surveillance Network, United States, July–October, 2017 and 2018," Morbidity and Mortality Weekly Report 68(12), Centers for Disease Control and Prevention; a work of the United States government in the public domain. An erratum has been published for this report. Original report.