title: Exposure to farming in early life and development of asthma and allergy: a cross-sectional survey.
abstract: BACKGROUND
  A farming environment protects against development of asthma, hay fever, and atopic sensitisation in children. We aimed to establish whether increased exposure to microbial compounds has to occur early in life to affect maturation of the immune system and thereby reduces risk for development of allergic diseases.
  
  
  METHODS
  We did a cross-sectional survey in rural areas of Austria, Germany, and Switzerland. 2618 (75%) of 3504 parents of 6-13-year-old children completed a standardised questionnaire on asthma, hay fever, and atopic eczema. Children from farming families, and a random sample of non-farmers' children, who gave consent for blood samples to be obtained for measurements of specific serum IgE antibodies to common allergens were invited to participate (n=901).
  
  
  RESULTS
  Exposure of children younger than 1 year, compared with those aged 1-5 years, to stables and consumption of farm milk was associated with lower frequencies of asthma (1% [3/218] vs 11% [15/138]), hay fever (3% [7] vs 13% [18]), and atopic sensitisation (12% [27] vs 29% [40]). Protection against development of asthma was independent from effect on atopic sensitisation. Continual long-term exposure to stables until age 5 years was associated with the lowest frequencies of asthma (0.8% [1/122]), hay fever (0.8% [1]), and atopic sensitisation (8.2% [10]).
  
  
  CONCLUSIONS
  Long-term and early-life exposure to stables and farm milk induces a strong protective effect against development of asthma, hay fever, and atopic sensitisation.
authors.affiliation: Paediatric Pulmonology and Allergology, Children's Hospital, Salzburg, Austria. J.Riedler@Lks.at
authors.forename: J
authors.initials: J
authors.lastname: Riedler
authors.forename: C
authors.initials: C
authors.lastname: Braun-Fahrländer
authors.forename: W
authors.initials: W
authors.lastname: Eder
authors.forename: M
authors.initials: M
authors.lastname: Schreuer
authors.forename: M
authors.initials: M
authors.lastname: Waser
authors.forename: S
authors.initials: S
authors.lastname: Maisch
authors.forename: D
authors.initials: D
authors.lastname: Carr
authors.forename: R
authors.initials: R
authors.lastname: Schierl
authors.forename: D
authors.initials: D
authors.lastname: Nowak
authors.forename: E
authors.initials: E
authors.lastname: von Mutius
mesh_terms: D000293:Adolescent; D000383:Agriculture; D001249:Asthma / Q000453:epidemiology / Q000209:etiology* / Q000276:immunology; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D004781:Environmental Exposure; D005260:Female; D006801:Humans; D006967:Hypersensitivity / Q000453:epidemiology / Q000209:etiology / Q000276:immunology*; D007073:Immunoglobulin E / Q000097:blood*; D007223:Infant; D018811:Maternal Exposure; D012423:Rural Health; D011795:Surveys and Questionnaires; D013557:Switzerland / Q000453:epidemiology
chemical_list: D007073:Immunoglobulin E