Babies and young children are prone to infection with respiratory syncytial virus (RSV), and new research shows that the condition is worsened if they’re exposed to cigarette smoke.

A family history of allergies or asthma also has an impact, but for the good, according to a report in the medical journal Pediatrics.

“Physicians should encourage parents/caregivers not to expose their children to secondhand smoke, especially during a respiratory tract illness,” Dr. Mario Castro from Washington University School of Medicine, St. Louis, told AMN Health.

Castro studied 206 hospitalized children enrolled in the RSV Bronchiolitis in Early Life (RBEL) study. Bronchiolitis is an inflammation of the small airways in the lungs, which can result from respiratory infections.

The infants in the study who were exposed to cigarette smoke had significantly lower oxygen concentrations in their blood during hospitalization for RSV than did unexposed infants, the team reports.

Infants with a family history of allergies or asthma, on the other hand, had higher oxygen levels during hospitalization, the study found.

Other factors linked to RSV bronchiolitis severity were younger age, white race, and maternal smoking.

“All children with respiratory tract illness during the RSV season (December through March in most areas) suggestive of bronchiolitis should be screened for RSV,” Castro said. “Prompt diagnosis of RSV infection in children is helpful in making sure that the child is stable and in provision of bronchodilators to clear and open the airways.”

The RBEL study, sponsored by the National Institutes of Health, is “currently in its sixth year of follow-up,” Castro added. The investigators are hoping to see if other factors such as breastfeeding, childcare, or genetics, “have an impact on modifying this risk in children exposed to a serious illness with RSV.”

SOURCE: Pediatrics, January 2005.