title: Primary prevention of childhood asthma and allergic disorders.
abstract: OBJECTIVE
  The prevalence of asthma and allergic disorders in childhood is increasing in many parts of the world. This review focuses on recent findings with regard to environmental risk factors and their manipulation in the primary prevention of these diseases in childhood.
  
  
  RESULTS
  Recent studies have failed to resolve the controversy on the subject of exposure to indoor aeroallergens and the risk of sensitization and asthma in childhood. Bronchiolitis due to respiratory syncytial virus in infancy is associated with a significant increase in risk of asthma, but not atopy. In the prevention of these diseases, the effects of breastfeeding are controversial, with studies showing a protective effect in children without allergic predisposition, but other studies showing no effect or even the potential for an increased asthma risk. A significant reduction in the prevalence of doctor-diagnosed asthma at 7 years was found in a randomized controlled multifaceted (reduction of inhaled and ingested allergens) intervention study of high-risk infants. Other intervention measures, such as an education program on how to reduce exposure, the use of probiotics, and immunization against infections, all showed some protective effects.
  
  
  CONCLUSIONS
  More research is required, especially with regard to longer periods of follow-up for all current intervention studies aimed at reducing exposure, the onset and duration of intervention, and other novel intervention measures in the primary prevention of asthma and allergic diseases in childhood.
authors: Occupational and Environmental Lung Diseases Unit, Respiratory Division, Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada. myeung@interchange.ubc.ca
authors: Moira
authors: M
authors: Chan-Yeung
authors: Allan
authors: A
authors: Becker