THE NATURAL COURSE OF SENSITIZATION AND ATOPIC DISEASE IN INFANCY ANDCHILDHOOD

A number of epidemiological studies indicate that the prevalance of al lergic airway diseases has been increasing over recent decades, especi ally in western industrialised countries, for reasons which are not ye t completely understood (1, 2, 3). Changes in life style or an increas e in indoor allergen exposure due to higher indoor temperature and hum idity have been suggested as potential determinants, although evidence for both hypotheses is indirect (4). During the last years we have be en following a birth cohort born in 1990 in order to understand the in fluence of the major genetic and environmental determinants, which are modulating the development of allergic sensitisation and the incidenc e of atopic symptoms. Sensitisation to indoor allergens has been demon strated to be one of the major risk factors for the development of ast hma in childhood (5, 6, 7, 8). Several cross-sectional studies in olde r children indicate that specific sensitisation to house dust mites is related to dust mite allergen concentrations in mattress dust (9, 10) . Exposure threshold levels for several indoor allergens have been pro posed, but individuals vary widely in their susceptibility to levels o f exposure, and no absolute value has been identified which could gene rally ensure minimum risk.