Viral Bronchiolitis in Children

Few diseases have a greater effect on the health of young children than viral lower respiratory tract illness. Approximately 800,000 children in the United States, or approximately 20% of the annual birth cohort, require outpatient medical attention during the first year of life because of illness caused by respiratory syncytial virus (RSV).(1) Between 2% and 3% of all children younger than 12 months of age are hospitalized with a diagnosis of bronchiolitis, which accounts for between 57,000 and 172,000 hospitalizations annually.(1-4) Estimated nationwide hospital charges for care related to bronchiolitis in children younger than 2 years of age exceeded $1.7 billion in 2009.(5) Globally, in 2005, RSV alone was estimated to cause 66,000 to 199,000 deaths among children younger than 5 years of age, with a disproportionate number of these deaths occurring in resource-limited countries.(6,7) In the United States, by contrast, bronchiolitis due to RSV accounts for fewer than 100 deaths in young children annually.(8) This review describes the current understanding of bronchiolitis, including the increasing number of viruses that are known to cause it, the current understanding of its pathogenesis, the importance of environmental and host genetic factors, and the roles of season, race, and sex in bronchiolitis attack rates and subsequent episodes of wheezing. In addition, guidelines from the American Academy of Pediatrics regarding the diagnosis, management, and prevention of bronchiolitis are summarized.(9,10)