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Having lived on a farm and protection against allergic diseases in Australia
S H Downs1, G B Marks, T Z Mitakakis
1Institute of Respiratory Medicine, University of Sydney, Sydney, Australia. shd@mail.med.usyd.edu.au
Background:
Farmers' children in northern Europe have a lower prevalence of atopy, hay fever and asthma than other children. Farms in Australia differ in scale and operation from those in Europe and the prevalence of allergic diseases in children is higher.
Objective:
To investigate whether having lived on a farm as a child in Australia is associated with a lower risk of allergic diseases.
Methods:
Cross-sectional study of children (n = 1500) aged 7-12 years from two rural towns: Wagga Wagga in a mixed farming region, and Moree in a crop farming region. Parents answered a questionnaire and children had a skin prick test for atopy.
Results:
Twenty percent of children had lived on a farm for at least 1 year. The effect of having lived on a farm differed between the towns (P < 0.001). It was associated with a lower risk of atopy in Wagga (adjusted odds ratio (aOR) 0.47, 95% confidence interval (CI) 0.32-0.72) but not in Moree (aOR 0.97, 95% CI 0.62-1.53). Children from Wagga were more likely to have lived on a livestock farm than children from Moree (26.1% vs. 9.1%, 95% CI for the difference 8.9-25.4).
Conclusion:
Having lived on a farm in Australia can confer protection against atopy in children. Further studies are needed to identify possible protective mechanisms associated with farm animals or to establish whether the protective effect is explained by other related exposures.