On roots of childhood asthma: the role of respiratory infections.

The prevalence of childhood asthma has increased throughout the last decades, but the reasons for the increase still remain unresolved. However, the debate has recently focused on the role of infections, and microbial exposure in general, in the development of childhood asthma. Many studies have suggested that there is an inverse relation between certain infections and the risk of asthma. This article outlines the contemporary role of childhood asthma in public health, reviews the importance of topical respiratory pathogens in the development of childhood asthma, and provides an example how selection bias may have caused controversy in previous studies assessing the role of infections in the development of childhood asthma.