Differences in both prevalence and titre of specific immunoglobulin E among children with asthma in affluent and poor communities within a large town in Ghana

Abstract

BackgroundReports from several African countries have noted an increasing prevalence of asthma in areas of extensive urbanization.ObjectiveTo investigate the relevance of allergen-specific sensitization and body mass index (BMI) to asthma/wheezing and exercise-induced bronchospasm (EIB) among children from affluent and poorer communities within a large town in Ghana.MethodsChildren with physician-diagnosed asthma and/or current wheezing aged 9–16 years (n=99; cases) from three schools with differing socio-economic backgrounds [urban affluent (UA), urban poor (UP) or suburban/rural (SR)] were recruited from a cross-sectional study (n=1848) in Kumasi, Ghana, and matched according to age, sex and area of residence with non-asthmatic/non-wheezy controls. We assayed sera for IgE antibodies to mite, cat, dog, cockroach, Ascaris and galactose-α-1,3-galactose.ResultsChildren from the UA school had the lowest total serum IgE. However, cases from the UA school had a higher prevalence and mean titre of sIgE to mite (71.4%, 21.2 IU/mL) when compared with controls (14.3%, 0.8 IU/mL) or cases from UP (30%, 0.8 IU/mL) and SR community (47.8%, 1.6 IU/mL). While similar findings were observed with EIB in the whole population, among cases there was no difference in IgE antibody prevalence or titre between children with or without EIB. BMI was higher among UA children with and without asthma; in UP and SR communities, children with EIB (n=14) had a significantly higher BMI compared with children with asthma/wheezing without EIB (n=38) (18.2 vs. 16.4, respectively, P<0.01).Conclusions and Clinical RelevanceIn the relatively affluent school, asthma/wheezing and EIB were associated with high titre IgE antibodies to mite, decreased total IgE, and increased BMI. This contrasted with children in the urban poor school and suggests that changes relevant to a Western model of childhood asthma can occur within a short geographical distance within a large city in Africa.Cite this as: W. Stevens, E. Addo-Yobo, J. Roper, A. Woodcock, H. James, T. Platts-Mills and A. Custovic, Clinical & Experimental Allergy, 2011 (41) 1587–1594.

The allergy epidemics: 1870-2010

“…In pre-hygiene villages, children and adults generally have elevated total serum IgE, low titer IgE antibodies to mite and other allergens, and if tested will often have IgE antibodies to parasite related antigens such as Ascaris or the tick related galactose alpha-1, 3-galactose 44, 46, 47 . In post hygiene society mean total IgE levels are lower, and specific IgE antibodies to common inhalant allergens are common and often present in high titer.…”

Allergy in severe asthma

“…The association between atopy and asthma appears specific to inhalant allergens (4). In general, atopic sensitization is defined either when allergen-specific serum IgE (sIgE) is detected, or a positive skin prick test (SPT) to extracts made from whole-allergen sources (11,12), often using arbitrary cut-off points of sIgE >0.35 KU/l, or a mean wheal diameter ≥3 mm.…”

“…Numerous epidemiological studies have demonstrated that atopic sensitization is a strong risk factor for asthma in childhood (1, 2) and adulthood (3), both in the developed (3) and in the developing countries (1,2,4), supporting the notion that asthma is in part an allergic disease. However, the role of allergy in severe asthma remains the issue of considerable controversy.…”

The hygiene hypothesis revisited

“…As discussed in previous reviews [3,4], these original observations explain only part of the story. Several recent articles highlight the increasing prevalence of asthma/ atopy in developing nations, despite little change in the infectious agents afflicting children [5][6][7][8].…”