December 12, 2008

New cold virus linked with childhood asthma

Featured Image

Kathryn Miller, M.D., demonstrates saying "Ah" with patient Davin Miles, 4, as his parents, Bill and Gwen Miles, look on. (photo by Dana Johnson)

New cold virus linked with childhood asthma

A study by researchers at the Monroe Carell Jr. Children's Hospital at Vanderbilt implicates a new virus in an old, but growing problem: childhood asthma.

Lead author Kathryn Miller, M.D., and colleagues surveyed young children hospitalized for respiratory illness and fever over two years and two geographic locations.

The study, published online this month by the Journal of Allergy and Clinical Immunology, documented a newly described group of rhinoviruses called HRV-C and found it accounted for almost half of rhinovirus-related asthma.

Miller said these findings may help explain the annual “September spike” in pediatric asthma hospitalizations.

“HRV-C was associated with wheezing, and we saw it distinctly in the fall. That held true in both years. This study begs the question of whether HRV-C explains the fall spike in asthma,” said Miller.

The study took place from 2001 to 2003 with children age 5 or younger, hospitalized in either Davidson County, Tenn., or Monroe County, N.Y.

The children were swabbed, and the viruses in the samples were DNA-tested to determine the presence of rhinoviruses. About a quarter of the children had rhinoviruses, but two types, HRV-A and the previously undescribed HRV- C, were the most common.

“While this virus has not been described in years past, we believe it has been around for a long time because of its prevalence in this study and other studies in Jordan, Hong Kong and Australia,” said Miller.

HRV-C has been difficult to find in the past because no one has been able to culture the virus. The Vanderbilt researchers found it using a form of DNA testing called Real-Time Reverse Transcription-Polymerase Chain Reaction (RT-PCR).

Using this technology, Miller was not only able to show rhinovirus is associated with about a quarter of pediatric asthma hospitalizations, but also that HRV-C specifically shows up in the fall and tends to affect children who are a little older (a median age of 15 months versus 7 months).

“With this study and some that are still under way, we are finding that HRV-C may be the more dangerous of the two prominent groups (HRV-A and C), but more study is needed,” said Miller.

What is not known is whether HRV-C, or other rhinoviruses, actually cause asthma, or whether they are triggers for the disease in children who are already susceptible.

“And while I think it's becoming clear that rhinovirus plays a major role in asthma exacerbations, what we don't know is the mechanisms and what we might do to prevent or treat it,” Miller said.

But that is part of what Miller and colleagues are working on next. Miller said she is utilizing samples and data from the Tennessee Children's Respiratory Initiative, a longitudinal investigation of children from infancy through age 6, run by principal investigator Tina Hartert, M.D., associate professor of Medicine and director of the Center for Asthma Research, to determine the role of respiratory viruses and environmental factors on the development of asthma and allergy.