By the time they're 2 years old, almost all children have been infected with respiratory syncytial virus (RSV), an infection of the respiratory tract that in some children causes the lung infection bronchiolitis. Every year, about 100,000 people - mostly infants - are hospitalized because of RSV infection. Researchers from the Washington University School of Medicine in St. Louis, Missouri, investigated the factors that influence the severity of RSV bronchiolitis in children.
Between 1998 and 2001, 206 infants under 12 months of age who visited the emergency department or were admitted to the hospital for RSV bronchiolitis infection participated in the study. Researchers checked each child's medical record from the hospital visit or admission, and parents answered questions about the child's feeding habits, his or her exposure to cigarette smoke during and after pregnancy, prior illnesses, and the family history of conditions like asthma, hay fever, eczema, or allergies. Dust samples were taken from each infant's home, and blood samples were taken from the infants and tested for signs of allergies.
The infant's age played a major role in the severity of the infection - the youngest infants had the lowest levels of oxygen in the blood (oxygen saturation level), an indication of severe infection. In addition, babies who'd been exposed to cigarette smoke after birth also had lower oxygen saturation levels than babies who were not exposed to cigarette smoke. In contrast, infants who had a family history of allergic conditions like asthma or hay fever, especially those whose mothers had the disorders, had an increased oxygen saturation level - the presence of this risk factor appeared to protect them against more severe forms of RSV bronchiolitis. Also, black infants tended to have less severe RSV bronchiolitis than white infants.
What This Means to You: The results of this study indicate that the youngest infants and those who have been exposed to cigarette smoke after birth have the highest risk of severe RSV bronchiolitis. To help protect your child, make sure he or she isn't exposed to cigarette smoke by you or others in your household. In addition, if your young infant develops symptoms of a lower respiratory tract infection during RSV season (which is typically from late fall through early spring), call your child's doctor. Symptoms that may indicate a lower respiratory tract infection may include rapid shallow breathing, rapid heartbeat, irritability, fever, poor appetite, and vomiting.
Source: Joseph P. Bradley, BS; Leonard B. Bacharier, MD; JoAnn Bonfiglio, RN, MSN; Kenneth B. Schechtman, PhD; Robert Strunk, MD; Gregory Storch, MD; Mario Castro, MD, MPH; Pediatrics, January 2005
Reviewed by: Steven Dowshen, MD
Date reviewed: February 2005
