SAN DIEGO – Enterovirus D68 appeared more virulent – but not more lethal – than rhinovirus and other strains of enterovirus among children, said the authors of a single-center study.
The pulmonary pathogen was linked to higher rates of respiratory distress, hospital admission, and magnesium sulfate therapy, but patients were no more likely to die or require critical care unit admission than were those infected with other EV genotypes or rhinovirus, said Dr. Dominik Mertz of the division of infectious diseases at McMaster University, in Hamilton, Ont.
Amy Karon/Frontline Medical News
Dr. Jeffrey Pernica (left) and Dr. Dominik Mertz.
The study also uncovered no evidence of EV-68 transmission at the hospital, Dr. Mertz and his associates said at an annual scientific meeting on infectious diseases.
In 2014, an outbreak of EV-D68 in the United States included more than 1,000 confirmed cases, almost all among children, and many of whom had comorbid asthma or a history of wheezing. Fourteen patients died, and the Centers for Disease Control and Prevention noted that millions more individuals probably had milder EV-D68 infections for which they were never tested.
Dr. Mertz and his associates studied children who presented consecutively to the hospital during the 3 months between Aug. 1 and Oct. 31, 2014. During that time, nasopharyngeal swabs that were positive for EV or rhinovirus were automatically tested for EV-D68. The researchers matched EV-D68–positive patients with children who were positive for rhinovirus or other EVs on the basis of sex, age, and date of presentation to the hospital.
Almost a third (93 of 297; 31%) of rhinovirus or EV samples were positive for EV-D68. Among 87 matched pairs, EV-D68 infection was associated with a threefold greater odds of respiratory distress (95% confidence interval, 1.47-6.14), and a more than twofold rise in the odds of needing magnesium sulfate therapy (odds ratio, 2.62; 95% CI, 1.06-6.47). There was a trend toward greater risk of hospital admission with EV-D68, although it was not statistically significant (OR, 2.29; 95% CI, 0.96-5.46; P = .06).
Notably, EV-68 did not increase the likelihood of death or CCU admission, while, influenza causes dozens of deaths among children in the United States every year, Dr. Mertz and his coinvestigator Dr. Jeffrey Pernica noted in an interview (MMWR. 2014 Jun 6:63[22];483-90). Studies have yet to compare the morbidity and mortality burdens of influenza, respiratory syncytial virus, and EV-D68, and they would like to do so, they said.
“There was a lot of fuss made about EV-D68,” said Dr. Mertz. “But we have flu every year, and many more kids get the flu and die of flu than EV-D68.”
Patients with EV-D68 infection were more likely than others to have a family history of atopy (OR, 2.25) and a personal history of asthma or wheezing (OR, 1.77), hay fever (1.22), and eosinophilia (4.5), although none of these associations reached statistical significance, the investigators reported. “It seems reasonable to hypothesize that EV-D68 is a more virulent pulmonary pathogen to those with preexisting atopic disease than other rhinoviruses and enteroviruses,” Dr. Mertz and his associates wrote in an associated article (CMAJ. 2015 Oct. 13. doi: 10.1503/cmaj.150619). “We can hypothesize that these children are more likely to have respiratory distress because of the combination of allergy and EV-D68, but why the same doesn’t hold true for rhinovirus or other enterovirus strains, we don’t know,” Dr. Mertz said.
The investigators received no funding for the study and reported no conflicts of interest.