Exposure to a high concentration of mite allergen in early infancy is a risk factor for developing atopic dermatitis: a 3-year follow-up study.

The cause of allergy is multi-factorial, and the development of an allergic disease seems to be the result of an interaction between genetic and environmental factors. The goal for preventing the development of allergic diseases is to avoid sensitization to allergens. The aim of this work was to study whether or not exposure to environmental allergens early in infancy would influence the occurence of various allergic diseases in later life. On an annual basis, a total of 931 healthy newborns were followed-up until they reached 3 years of age. The occurence of allergic diseases was recorded by trained medical students during visits. Measurement of Dermatophagoides pteronyssinus (Der p 1) concentration in house dust was performed when each baby was 18 and 36 months old. Total and specific immunoglobulin E (IgE) antibodies against Der p 1, cow's milk, and egg white were evaluated at birth and at 18 months of age. The following results were obtained: at 3 years of age, 10.4% had bronchial asthma (BA), 21.4% atopic dermatitis (AD), 7.0% urticaria, and 46.8% had experienced wheezing; higher family allergy scores led to a higher incidence of AD (p=0.0012); exposure to a mite allergen concentration of 1 microg/g of dust may be associated with a higher incidence of AD (p=0.0156); the presence of Der p 1 IgE antibody at 18 months of age was associated with a higher incidence of BA (p=0.0001); and children sensitized to egg whites at 18 months of age had an increased risk of developing AD at 3 years of age (p=0.0187). Hence, early exposure to mite allergen is a risk factor for the development of atopic dermatitis, but seems not to be related to the development of bronchial asthma. Early sensitization to egg whites increases the risk of developing AD. The early detection of serum Der p 1 IgE antibody is associated with a higher incidence of bronchial asthma.