Cigarette smoke worsens respiratory infections in infants

RSV more severe in children who live with smokers

Dr. Mario Castro and nurse Michelle Jenkerson visit with RBEL study patient and RSV infection survivor Wil Klages and his mom, Peg Klages.
Dr. Mario Castro and nurse Michelle Jenkerson visit with RBEL study patient and RSV infection survivor Wil Klages and his mom, Peg Klages.

Studying Respiratory Syncytial Virus (RSV) to learn what puts children at risk for the most severe infections, Washington University researchers at St. Louis Children’s Hospital found that a child’s age at the time of infection and whether that child lives with a smoker could mean the difference between the sniffles and the intensive care unit.

RSV infection is common in children but sometimes can be hard for parents to recognize. By two years of age, 95 percent of all children have been exposed to RSV, but the symptoms can range from a mild cold all the way to serious pneumonia, which requires a child to be hospitalized and placed on a ventilator. The Washington University researchers have been trying to learn why some kids have a relatively easy time while others get so very sick.

The research team has been following 206 children since they were hospitalized or treated in the Emergency Department at St. Louis Children’s Hospital. The children are part of a project called the RSV Bronchiolitis in Early Life (RBEL) study. The infants all were under 12 months of age when they were enrolled in the RBEL study and had a wide range in the severity of their RSV infection, according to Mario Castro, M.D., associate professor of medicine and pediatrics at Washington University School of Medicine and principal investigator of the RBEL study.

After the children were treated at the hospital and recruited into the study, Castro and colleagues looked at medical records and measured the children’s oxygen saturation levels during RSV infection. The lower the oxygen saturation, the more serious the infection. Later, they went to the children’s homes and vacuumed up dust and allergens to see whether those products might have played a role in the severity of RSV infections.

Mario Castro

“We were thinking that the kids who came from homes that had high allergen levels would already be compromised because they would have a reaction to those allergens and develop inflammation in their windpipes, so they would tend to do worse with RSV,” Castro says. “But we found that even in the kids who came from the homes with the highest allergen levels, there was no increased risk.”

Having a mother with allergies or asthma also tended to have a protective effect. Those children whose mothers had allergies or asthma tended to have less serious RSV infections.

That’s somewhat surprising because the virus has been linked to the risk for asthma later on in life. As the children in the RBEL study get older, they will be followed to see if they develop asthma problems.

“We believe the severity of that initial RSV infection has a role in increasing the risk for asthma later in childhood,” Castro says. But he won’t know for sure until the children get older.

Bradley JP, Bacharier LB, Bonfiglio J, Schechtman KB, Strunk R, Storch G, Castro M. Severity of Respiratory Syncytial Virus Bronchiolitis is Affected by Cigarette Smoke Exposure and Atopy. Pediatrics, vol.115; pp. 7-14, Jan. 2005.

The full-time and volunteer faculty of Washington University School of Medicine are the physicians and surgeons of Barnes-Jewish and St. Louis Children’s hospitals. The School of Medicine is one of the leading medical research, teaching and patient care institutions in the nation, currently ranked second in the nation by U.S. News & World Report. Through its affiliations with Barnes-Jewish and St. Louis Children’s hospitals, the School of Medicine is linked to BJC HealthCare.