title: Importance of allergy in asthma: an epidemiologic perspective.
abstract: There has been a global epidemic of asthma during the past half-century. More recently, the prevalence has leveled off or declined in many Western countries, whereas the prevalence in less affluent nations is still increasing. The reasons for this and the different geographical patterns of asthma prevalence remain unclear. This paper provides an epidemiologic perspective on whether allergen exposure and allergies can explain these trends. In particular, the paper discusses 1) geographical and temporal trends in asthma and the role of allergens and allergy, 2) the importance of nonallergic mechanisms, 3) nonallergenic exposures that may modify the risk of allergies and asthma, and 4) new and emerging risk and protective factors. Although allergy and asthma are closely related, allergen exposure and allergy alone cannot explain current time trends and geographical patterns of asthma. Population-based studies focusing on recently identified risk and protective factors may provide further insight.
authors.affiliation: Centre for Public Health Research, Massey University, P.O. Box 756, Wellington 6140, New Zealand. j.douwes@massey.ac.nz
authors.forename: Jeroen
authors.initials: J
authors.lastname: Douwes
authors.forename: Collin
authors.initials: C
authors.lastname: Brooks
authors.forename: Christine
authors.initials: C
authors.lastname: van Dalen
authors.forename: Neil
authors.initials: N
authors.lastname: Pearce
mesh_terms: D000485:Allergens / Q000009:adverse effects* / Q000276:immunology; D001249:Asthma / Q000453:epidemiology / Q000209:etiology / Q000276:immunology; D004781:Environmental Exposure / Q000009:adverse effects*; D005260:Female; D006801:Humans; D006967:Hypersensitivity / Q000150:complications / Q000453:epidemiology / Q000276:immunology; D008297:Male; D012307:Risk Factors
chemical_list: D000485:Allergens