title: Influence of early and current environmental exposure factors on sensitization and outcome of asthma in pre-school children.
abstract: BACKGROUND
  Exposure to furred pets in early life has been considered to increase the risk of allergic sensitization and consequent development of asthma later in children. However, recently, it has been suggested that early exposure to pets prevents sensitization. The aim of this study was to evaluate the importance of early exposure to pets and other environmental risk factors in asthmatic children.
  
  
  METHODS
  This is a follow-up study after 2 years of a previously investigated group of 193 asthmatic children, aged 1-4 years. The study was completed by 181 children, who were clinically examined; serum IgE antibodies were also measured and a questionnaire was answered.
  
  
  RESULTS
  Children with reported exposure to cats during the first 2 years of life were more likely to have developed sensitization to cat by 4 years of age than unexposed children. High levels of cat allergen (Fel d 1> or =8 microg/g dust) were associated with an increased risk of sensitization to cat and, in combination with tobacco smoke, also with the development of more severe asthma.
  
  
  CONCLUSIONS
  In young asthmatic children, early exposure to cat and tobacco smoke increased the risk of allergic sensitization and further development of more severe asthma later in childhood.
authors: Department of Environmental health, Karolinska Hospital, Stockholm, Sweden.
authors: E
authors: E
authors: Melén
authors: M
authors: M
authors: Wickman
authors: S L
authors: SL
authors: Nordvall
authors: M
authors: M
authors: van Hage-Hamsten
authors: A
authors: A
authors: Lindfors
mesh_terms: D000485:Allergens / Q000009:adverse effects; D000818:Animals; D001249:Asthma / Q000453:epidemiology / Q000209:etiology*; D002415:Cats; D002669:Child Welfare; D002675:Child, Preschool; D016001:Confidence Intervals; D004285:Dogs; D004781:Environmental Exposure / Q000009:adverse effects*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007114:Immunization; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D016017:Odds Ratio; D011852:Radioallergosorbent Test / Q000379:methods; D012307:Risk Factors; D012720:Severity of Illness Index; D012882:Skin Tests; D012907:Smoking / Q000009:adverse effects; D013548:Sweden / Q000453:epidemiology; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D000485:Allergens