Inverse association between farm animal contact and respiratory allergies in adulthood: protection, underreporting or selection?

Allergy. 2006 Apr;61(4):443-6. doi: 10.1111/j.1398-9995.2006.00995.x.


Background: It has been argued that the inverse association between exposure to farm animals and nasal allergies observed in children and adults might be because of self-selection.

Aims: We aimed to assess the health-based selection out of farming in adults.

Material and methods: A cross-sectional study was carried out in a rural region. Overall, 4053 inhabitants (63%) aged 18-44 years responded to a questionnaire on respiratory diseases, life-time exposure to farming environments and potential confounders. For 2678 of these, specific immunoglobulin E to common allergens was available. The outcome was: (i) sensitization and symptoms of nasal allergies (symptomatic sensitization); (ii) sensitization without symptoms of nasal allergies (asymptomatic sensitization).

Results: Farm animal contact in childhood was associated with a decreased risk of symptomatic and asymptomatic sensitization. Continued exposure to farm animals in adulthood further decreased the odds ratio of symptomatic (odds ratio 0.2; 95% confidence interval 0.1, 0.4) but not asymptomatic sensitization (0.7; 0.4, 1.1). Starting farm animal contact in adulthood even increased the odds ratio of asymptomatic sensitization (2.4; 1.1, 5.2).

Conclusions: The preventive effect of childhood contact to farm animals against sensitization continues into adulthood. However, in adulthood self-selection based on symptoms and underreporting of symptoms might also play a role.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Age Factors
  • Allergens / immunology*
  • Animals
  • Animals, Domestic*
  • Asthma / prevention & control*
  • Child
  • Cross-Sectional Studies
  • Female
  • Humans
  • Hypersensitivity / prevention & control*
  • Male
  • Middle Aged


  • Allergens