Bronchiolitis in infants.

Bronchiolitis is a common cause of wheezing among infants. Respiratory syncytial virus (RSV) is the most common infectious agent to cause bronchiolitis, and RSV infection accounts for more than 125,000 hospitalizations per year in the United States. Beyond supportive measures, the care of infants with bronchiolitis remains controversial. Practitioners continue to treat infants with a variety of pharmacologic agents, despite limited evidence of their efficacy. Investigators continue to search for the safest and most cost-effective methods to treat infants with bronchiolitis, not only to overcome obstructive symptoms during the acute illness, but also to prevent recurrent symptoms of airway obstruction that occur in some children for years after their initial episode of bronchiolitis. Improved understanding of the pathogenesis of RSV infection and of virus-host interactions may one day lead to the development of agents that alter the initial inflammatory response and strategies that help prevent recurrent episodes of wheezing and the development of asthma after acute bronchiolitis.