In recent decades there have been marked increases in asthma prevalence in Western countries. More recently, asthma prevalence has peaked, or even begun to decline, in Western countries, but many low and middle income countries are now beginning to experience increases in prevalence (although there is no evidence of increases in prevalence in India to date). “Established” risk factors for asthma cannot account for the global prevalence increases, or the international patterns that have been observed, or the recent declines in prevalence in some Western countries. It seems that as a result of the “package” of changes in the intrauterine and infant environment that are occurring with “Westernization”, we are seeing an increased susceptibility to the development of asthma and/or allergy. There are a number of elements of this “package” including changes in maternal diet, increased fetal growth, smaller family size, reduced infant infections and increased use of antibiotics and paracetamol, and immunization, all of which have been (inconsistently) associated with an increased risk of childhood asthma, but none of which can alone explain the increases in prevalence. It is likely that the “package” is more than the sum of its parts, and that these social and environmental changes are all pushing the infants’ immune systems towards an increased risk of asthma.
Asthma Epidemiology Childhood Risk factors
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Conflict of Interest
Role of Funding Source
The Centre for Public Health Research is supported by a Programme Grant from the Health Research Council of New Zealand.
Peat JK, Tovey E, Toelle BG, et al. House dust mite allergens: a major risk factor for childhood asthma in Australia. Am J Respir Crit Care Med. 1996;153:141–6.PubMedGoogle Scholar
Douwes J, Gibson P, Pekkanen J, Pearce N. Non-eosinophilic asthma: importance and possible mechanisms. Thorax. 2002;57:643–8.PubMedCrossRefGoogle Scholar
Asher MI, Keil U, Anderson HR, et al. International Study of Asthma and Allergies in Childhood (ISAAC): rationale and methods. Eur Respir J. 1995;8:483–91.PubMedCrossRefGoogle Scholar
Asher MI, Montefort S, Björkstén B, et al; ISSAC Phase Three Study Group. Worldwide time trends in the prevalence of symptoms of asthma, allergic rhinoconjunctivitis, and eczema in childhood: ISAAC Phases One and Three repeat multicountry cross-sectional surveys. Lancet. 2006;368:733–43.PubMedCrossRefGoogle Scholar
Beasley R, Keil U, Von Mutius E, et al. Worldwide variation in prevalence of symptoms of asthma, allergic rhinoconjunctivitis and atopic eczema: ISAAC. Lancet. 1998;351:1225–32.CrossRefGoogle Scholar
Asher MI, Anderson HR, Stewart AW, et al. Worldwide variations in the prevalence of asthma symptoms: International Study of Asthma and Allergies in Childhood (ISAAC). Eur Respir J. 1998;12:315–35.CrossRefGoogle Scholar
Pearce N, Aït-Khaled N, Beasley R, et al; and ISSAC Phase Three Study Group.Worldwide trends in the prevalence of asthma symptoms: phase III of the International Study of Asthma and Allergies in Childhood (ISAAC). Thorax. 2007;62:757–65.CrossRefGoogle Scholar
Pearce N, Douwes J. The global epidemiology of asthma in children. Int J TubercLung Dis. 2006;10:125–32.Google Scholar
Pearce N, Douwes J, Beasley R. Asthma. In: Tanaka H, ed. Oxford textbook of public health. 4th ed. Oxford: Oxford University Press; 2002. pp. 1255–77.Google Scholar
Pearce N, Beasley R, Burgess C, Crane J. Asthma epidemiology: principles and methods. New York: Oxford University Press; 1998.Google Scholar
von Mutius E, Fritzsch C, Weiland SK, Röll G, Magnussen H. Prevalence of asthma and allergic disorders among children in United Germany: a descriptive comparison. BMJ. 1992;305:1395–9.CrossRefGoogle Scholar