Viruses and atopic sensitization in the first years of life.

Abstract

Reports indicating that in most cases of asthma the first symptoms of bronchial obstruction occur during the first years of life (1) have focused a great deal of attention on the environmental factors that may predispose to or protect against the development of the disease in early life. Because the great majority of wheezing lower respiratory illnesses (LRIs) in infancy and early childhood are associated with microbiological evidence of an acute viral infection (2), it is not surprising that there has been renewed interest in the role of viruses in the inception of asthma. It is now well established, on the other hand, that most cases of childhood asthma in school-age children are associated with evidence of sensitization to local aeroallergens (3). It is still unclear, however, whether sensitization to specific antigens is causally related to the development of asthma. In this article, the role of viral respiratory infections and of sensitization to aeroallergens as predisposing factors for asthma are assessed, with special reference to events occurring during the first years of life.