Respiratory Symptoms and Asthma in Two Farming Populations: A Comparison of Hutterite and Non‐Hutterite Children

Abstract

OBJECTIVE:To determine the prevalence of asthma and respiratory symptoms in a farming population of Hutterite and nonHutterite children. PARTICIPANTS AND SETTING: A population of 830 schoolage, farm-dwelling children in rural Saskatchewan that included 83 children residing in Hutterite farming colonies. METHODS: A cross-sectional survey questionnaire was sent to parents of children attending grades 1 to 5 in schools within a grain-growing and mixed-farming region of central Saskatchewan. The questionnaire was used to identify respiratory symptoms, environmental and host characteristics, and reported doctordiagnosed asthma. RESULTS:The prevalence of asthma in Hutterite children was 2.4% compared with 9.2% in non-Hutterite children. While Hutterite children did not differ from their farming counterparts with regard to the frequency of reported respiratory allergies, they were less likely to be exposed to cigarette smoke and to participate in farm-related activities. In the multivariate analysis, being Hutterite continued to be protective for asthma (odds ratio 0.21; 95% CI 0.05 to 0.89). CONCLUSION:The observed lower rate of asthma in Hutterite children than in non-Hutterite children may be related to both genetic factors and differences in farming and household factors between the two groups. suite à la page suivante MÉTHODOLOGIE : Un questionnaire transversal a été posté aux parents d'enfants de première à cinquième année d'écoles d'une région céréalière et de polyculture du centre de la Saskatchewan. Le questionnaire a permis de repérer les symptômes respiratoires, les caractéristiques environnementales et de l'hôte, de même que les cas d'asthme diagnostiqués par un médecin. RÉSULTATS : La prévalence d'asthme chez les enfants huttériens était de 2,4 %, par rapport à 9,2 % chez les enfants non-huttériens. Bien que la fréquence d'allergies respiratoires déclarées n'aient pas différé chez les enfants huttériens par rapport aux autres enfants de milieu agricole, les enfants huttériens étaient moins susceptibles d'être exposés à la fumée de cigarette et de participer aux activités agricoles. Dans l'analyse multivariée, le fait d'être Huttérien continuait de constituer un facteur de protection contre l'asthme (risque relatif 0,21; IC 95 % 0,05 à 0,89). CONCLUSION : Le taux moins élevé d'asthme observé chez les enfants huttériens par rapport aux enfants non-huttériens peut être relié à la fois à des facteurs génétiques et à des différences dans les modes agricoles et les habitudes familiales des deux groupes.

The many faces of the hygiene hypothesis

“…A large number of studies has documented that children raised on farms have a lower prevalence of hay fever and atopic sensitization in childhood, as well as in adulthood, whereas effects on asthma are more consistent for the atopic than the nonatopic phenotype. [73][74][75][76][77][78][79][80][81][82] Important exposures in these environments have been identified as animal sheds, 73,83 hay lofts (unpublished data), and the consumption of unpasteurized cows' milk. 73 The timing of the exposure played a crucial role because the protection was strongest when the exposures occurred in the first years of life compared with in later years.…”

Allergies, infections and the hygiene hypothesis – The epidemiological evidence

“…Children from a neighbourhood in the same village but much less exposed to farm activities serve as natural controls. There is rather consistent evidence showing that farm children have a significantly lower prevalence of hay fever and atopic sensitisation in childhood which is persisting into adulthood (Ernst and Cormier, 2000;Klintberg et al, 2001;Leynaert et al, 2001;Riedler et al, 2001;Portengen et al, 2002;Rennie et al, 2002;Remes et al, 2003;Eduard et al, 2004;Elliott et al, 2004;Radon et al, 2004a). It is still unclear which specific farm exposures explain the protective effect, but animal sheds, hay lofts and the consumption of unpasteurised cow's milk have so far all been identified as protective exposures (Riedler et al, 2001).…”

Exposure to ‘farming’ and objective markers of atopy: a systematic review and meta‐analysis

“…More recently, there has been growing interest in the role of microbial loads, environmental biodiversity, and diversity of human microbiota in the gut and skin, in the prevention of allergic diseases; a theory termed the 'biodiversity hypothesis' [8]. Some studies have suggested that childhood exposure to farming reduces the risk of atopic asthma as well as hay fever and atopic sensitization [9]; this association has now been partially explained by exposure to greater microbial diversity [10][11][12][13][14][15][16][17][18][19]. Some studies have suggested that childhood exposure to farming reduces the risk of atopic asthma as well as hay fever and atopic sensitization [9]; this association has now been partially explained by exposure to greater microbial diversity [10][11][12][13][14][15][16][17][18][19].…”

“…This theory has also been used to explain the parallel rise in other chronic inflammatory and autoimmune diseases [8]. Some studies have suggested that childhood exposure to farming reduces the risk of atopic asthma as well as hay fever and atopic sensitization [9]; this association has now been partially explained by exposure to greater microbial diversity [10][11][12][13][14][15][16][17][18][19].…”