Infections and asthma

Abstract

Infections have a variety of influences in the asthmatic patient. Respiratory syncytial virus (RSV) is the most common cause of wheezing illnesses in children under the age of 2 years and may be a risk factor for the inception of asthma in the first decade of life. Once asthma has become recognized clinically, rhinovirus is the leading cause of acute asthma exacerbations in adults and older children. Certain respiratory infections may induce chronic lower airway inflammation that may contribute to disease progression or severity in asthma. Paradoxically, some infections may even protect against the development of asthma. This article reviews the evidence for these associations and the mechanisms proposed to explain these various outcomes.