Airway Infection May Lead to Asthma

Respiratory syncytial virus (RSV), which can lead to lung and airway infections, is a major cause of respiratory problems in children. Could RSV infection be a precursor to asthma?

About half of children who experienced severe RSV bronchiolitis (a type of RSV infection) were diagnosed with asthma after the infection.

See a doctor if your child develops a lung infection.

Mario Castro, MD, MPH, of Washington University, and colleagues wanted to see what might be causing asthma in children who had RSV bronchiolitis as infants.

A study of 206 children who had RSV bronchiolitis before their first birthday,  found that 48 percent of these children were diagnosed with asthma before their seventh birthday.

A number of factors were associated with an increased asthma risk, including having a mother with asthma and dog allergies.

Among the studies results, children with:

• Mothers with asthma had a 5.2-fold increased risk of developing asthma
• Exposure to high levels of dog allergens had a 3.2-fold increased risk of asthma
• Airborne allergies by age 3 years had a 10.7-fold increased risk of asthma
• Regular wheezing in the first 3 years of life had a 7.3-fold increased risk of asthma
• Higher levels of CCL5 (a type of protein) in nasal epithelia (tissues involved in smell) during RSV infection had a 3.8-fold increased risk of asthma.

White children were 0.19 times less likely to develop asthma. Children in daycare were 0.18 times less likely to develop asthma.

These findings suggest a link between developing allergies before age 3 and an increased risk of asthma, the authors concluded.

There was also an association between increased CCL5 levels and asthma risk, they write.

While 206 children were included in the whole study, only 81 were analyzed for the CCL5 portion of the study.

Dr. Castro is a consultant and speaker for Asthmatx, is on the advisory board for Genentech, and is a speaker for AstraZeneca, Merck and GlaxoSmithKline. He received research support from Asthmatx, Amgen, Ception/Cephalon, Genentech, MedImmune, Merck, the National Institutes of Health, Novartis and GlaxoSmithKline.

Lead author Leonard Bacharier, MD, is on the advisory board for AstraZeneca, received honoraria from GlaxoSmithKline, and is on the advisory board and has received honoraria from Merck.

This study was supported by a grant from the National Institutes of Health. The research is published in the Journal of Allergy and Clinical Immunology.