title: Early life exposure to farm animals and symptoms of asthma, rhinoconjunctivitis and eczema: an ISAAC Phase Three Study.
abstract: BACKGROUND
  Associations between early life exposure to farm animals and respiratory symptoms and allergy in children have been reported in developed countries, but little is known about such associations in developing countries.
  
  
  OBJECTIVE
  To study the association between early life exposure to farm animals and symptoms of asthma, rhinoconjunctivitis and eczema in a worldwide study.
  
  
  METHODS
  Phase Three of the International Study of Asthma and Allergies in Childhood (ISAAC) was carried out in 6- to 7-year-old children in urban populations across the world. Questions about early life exposure to farm animals (at least once/week) were included in an additional questionnaire. The association between such exposures and symptoms of asthma, rhinoconjunctivitis and eczema was investigated with logistic regression. Adjustments were made for gender, region of the world, language, gross national income and 10 other subject-specific covariates.
  
  
  RESULTS
  A positive association was found between early exposure to farm animals and the prevalence of symptoms of asthma, rhinoconjunctivitis and eczema, especially in non-affluent countries. In these countries, odds ratios (ORs) for 'current wheeze', 'farm animal exposure in the first year of life' and 'farm animal exposure in pregnancy' were 1.27 [95% confidence interval (CI) 1.12-1.44] and 1.38 (95% CI 1.21-1.58), respectively. The corresponding ORs for affluent countries were 0.96 (95% CI 0.86-1.08) and 0.95 (95% CI 0.84-1.08), respectively.
  
  
  CONCLUSIONS
  Exposure to farm animals during pregnancy and in the first year of life was associated with increased symptoms of asthma, rhinoconjunctivitis and eczema in 6- to 7-year-old children living in non-affluent but not in affluent countries.
authors.affiliation: Institute for Risk Assessment Sciences and Julius Center for Health Sciences and Primary Care, University Medical Center Universiteit Utrecht, Utrecht, The Netherlands. b.brunekreef@uu.nl
authors.forename: Bert
authors.initials: B
authors.lastname: Brunekreef
authors.forename: Erika
authors.initials: E
authors.lastname: Von Mutius
authors.forename: Gary K
authors.initials: GK
authors.lastname: Wong
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Odhiambo
authors.forename: Tadd O
authors.initials: TO
authors.lastname: Clayton
mesh_terms: D000383:Agriculture; D000818:Animals; D001249:Asthma / Q000453:epidemiology*; D002648:Child; D003231:Conjunctivitis / Q000453:epidemiology*; D004485:Eczema / Q000453:epidemiology*; D004781:Environmental Exposure; D005260:Female; D006801:Humans; D008297:Male; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000453:epidemiology; D015995:Prevalence; D012220:Rhinitis / Q000453:epidemiology*; D012959:Socioeconomic Factors