Allergy
Statens Serum Institut has a yearlong allergy research program at the Department of Epidemiology Research. Particular focus is on the importance of exposures in utero and in the early years of life for later development of allergy.
How and why do we develop allergy?
Allergy occurs when the immune system by mistake continues to overreact towards an otherwise harmless substance in the environment. The most common forms of allergy are due to hypersensitivity to proteins from pollen, house dust mites, pets, domestic animals, mould funguses, or foods. Allergy is often hereditary conditioned, however some people develop allergy, even though no other family member has it. The occurrence of allergy has increased markedly over so few decades that environmental factors are assumed to be an important reason that allergy develops.
Atopic eczema in child
Allergic diseases are common
Atopic dermatitis, asthma, allergic rhinitis are examples of allergies that has become common diseases in many industrialised countries. In contrast, they are rarer in poor countries and rural areas. This is one reason there is particular research into hypothesis about the importance of pollution, indoor cli-mate, and more hygienic lifestyles (the hygiene hypothesis) in development of allergy.
The aim of our research is among others to study the hygiene hypothesis, and particularly to what extend vaccinations and infections, as well as the time of such exposures, are important in development of allergy. New theories under study concern the importance of parasitic helminth infections, the diet during pregnancy, and age at introduction of solid foods. The department also study genetic epidemiology, looking at the molecular level for genetic variance that influences e.g. asthma and atopic dermatitis.
Data sources used
The research programme includes studies based on data and blood samples from the National Birth Cohort. Other studies take advantage of population-based information about vaccine history and use of medication against allergy and infections. Finally, we conduct a range of prospective investiga-tions of children who are followed intensely in Guinea-Bissau and Greenland.
The Hygiene Hypothesis
The hygiene hypothesis was introduced in 1989 and raised attention because it gave a simple explanation to an unsolved riddle, notably why children with few or no siblings more often develop allergy than children with many siblings.
Over the past century declining family size, improved household amenities and higher standards of personal cleanliness have reduced opportunities for cross-infection in young families. This may have resulted in more widespread clinical expression of atopic disease
Professor David Strachan, BMJ 1989; 299(6710):1259-1260
The riddle is still not solved. Today the hygiene hypothesis is regarded a simplified hypothesis, among others because there has been no strong evidence that common childhood infections, e.g. measles, could have protected children against development of allergy. More recent research into the hygiene hypothesis has, for immunological reasons focused on changes in the intestinal flora or in the occurrence of helminth infections.
Peter Bager, SSI Researcher
Last revised 9 December 2011