title: Eosinophilia at the time of respiratory syncytial virus bronchiolitis predicts childhood reactive airway disease.
abstract: OBJECTIVE
  Bronchiolitis in infancy is viewed as a risk factor for childhood asthma, but factors predicting which infants will have persistent wheezing have not been identified. In addition, the nature of the association between the 2 conditions is uncertain. We wished to determine whether eosinophil counts at the time of acute bronchiolitis predicted the presence of wheezing in later childhood.
  
  
  METHODS
  We retrospectively identified infants hospitalized with bronchiolitis, determined peripheral blood eosinophil counts at the time of bronchiolitis, and then contacted their families when they had reached 7 years of age.
  
  
  RESULTS
  Eosinophil counts at the time of bronchiolitis were greater in subjects who would have wheezing at 7 years of age (median: 98 cells/mm(3)) than in infants who would have no recurrent wheezing (median: 0 cells/mm(3)) or transient wheezing only up to 3 years of age (median: 0 cells/mm(3)). When the effects of family history of asthma, gender, and passive exposure to cigarette smoke were examined, only eosinophilia at the time of bronchiolitis demonstrated a statistically significant relationship to the presence of wheezing at 7 years of age.
  
  
  CONCLUSIONS
  Eosinophilia at the time of bronchiolitis generally predicts the development of wheezing persisting into later childhood. Therefore, the association of bronchiolitis and childhood asthma seems more likely to be attributable to an immunologic anomaly that precedes the development of, or is induced by, bronchiolitis rather than to structural damage to the airway as a result of bronchiolitis.
authors.affiliation: Department of Pediatrics, State University of New York at Buffalo, School of Medicine and Biomedical Sciences, and the Division of Infectious Diseases, Children's Hospital of Buffalo, Buffalo, New York.
authors.forename: D R
authors.initials: DR
authors.lastname: Ehlenfield
authors.forename: K
authors.initials: K
authors.lastname: Cameron
authors.forename: R C
authors.initials: RC
authors.lastname: Welliver
mesh_terms: D001990:Bronchiolitis, Viral / Q000453:epidemiology*; D002648:Child; D002675:Child, Preschool; D004804:Eosinophils; D005260:Female; D006801:Humans; D007223:Infant; D007958:Leukocyte Count; D008297:Male; D011237:Predictive Value of Tests; D011657:Pulmonary Eosinophilia / Q000453:epidemiology*; D012135:Respiratory Sounds; D018357:Respiratory Syncytial Virus Infections / Q000453:epidemiology*; D012189:Retrospective Studies; D012307:Risk Factors