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Discovering the causes of atopy

BMJ 1997; 314 doi: (Published 05 April 1997) Cite this as: BMJ 1997;314:987

Patterns of childhood infection and fetal growth may be implicated

  1. Seif Shaheen, Lecturera
  1. a Department of Public Health Medicine, Guy's and St Thomas's Hospital Medical and Dental School, St Thomas's Hospital, London SE1 7EH

    The marked increase in the prevalence of childhood asthma, eczema, and hay fever in Britain over the past 30 years or more is largely unexplained. However, it is likely to be attributable to a rise in the prevalence of atopy. This is characterised by exaggerated Th2 cell responses to common allergens with production of raised concentrations of allergen specific IgE. Although we now understand more about the genetics of atopy and the role of Th1 and Th2 cells in the control of IgE, the environmental causes of atopy have eluded us. Of increasing interest is the potential roles that patterns of childhood infection and fetal growth and maturation might have in the inception of atopy.

    The number of older siblings has been shown to be inversely related to the prevalence of adult hay fever and infant eczema.1 This observation led Strachan to propose in the BMJ in 1989 that atopy may have increased because of a fall in exposure to infections in early childhood through improved hygiene and reductions in family size and overcrowding in the home.1 Children are likely to experience more severe infections at an earlier age when the number of …

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