Early and sustained infant exposure to a farming environment could provide a strong protective effect against the development of asthma and other allergic diseases, suggest authors of a study in this week’s issue of THE LANCET.
Previous research has shown that a farming environment protects against the development of asthma, hay fever, and atopic sensitisation in children. Josef Riedler and colleagues from Salzburg Childrens Hospital, Austria, investigated whether increased exposure to bacteria and other micro-organisms has to occur early in life to affect immune-system maturation (thereby reducing the risk for the development of allergic diseases).
The investigators did a cross-sectional survey in rural areas of Austria, Germany, and Switzerland. 2618 parents completed a standardised questionnaire about occurrence of asthma, hay fever, and atopic eczema in children aged 6-13 years. From this survey, 812 children (319 with farming parents and 493 non-farming controls)were identified; a second survey was done in which parents gave details of timing, frequency, and intensity of children’s exposure to stables and farm and pet animals; mothers’ activity on the farm; duration of breastfeeding; timing of infants’ consumption of home-grown food and farm milk; infant vaccinations; and avoidance of allergens.
Children exposed to farm stables and who consumed farm milk were less likely to develop asthma if initial exposure occurred in the first year of life than children exposed between 1-5 years (1% compared with 11%). Similar risk reductions were found for hay fever (3% compared with 13%) and for atopic sensitisation (12% compared with 29%). Protection against development of asthma was independent from the effect on atopic sensitisation. Continual long-term exposure to stables until age 5 years was associated with the lowest frequencies of asthma (0.8%), hay fever (0.8%), and atopic sensitisation (8.2%).
Josef Riedler comments: "The results of our study may help our understanding of the origins of asthma and other allergic diseases, and have the potential to inform future allergy-prevention strategies."
Contact: Dr Josef Riedler,Paediatric Pulmonology,Children's Hospital,Muellner Hauptstrasse 48,A- 5020 Salzburg,Austria;T) 43-662-4482-2601;F) 43-662-4482-4784;E) J.Riedler@Lks.at
Journal
The Lancet