Background: The role of respiratory tract infections in the development of asthma is uncertain. Studies have found evidence for both positive and negative effects of respiratory tract infections in infancy on the risk of development of asthma. The purpose of this study was to explore how respiratory infections in infancy influence the development of asthma in children.
Material and methods: This study is a non-systematic literature review based on a search in Medline with the search terms: “childhood asthma” combined with “respiratory tract infections” and “risk factors”, limited to studies published in the period 2000 through august 2011. All studies that addressed the association I wanted to evaluate were included independent of methodological strengths and weaknesses. Review articles were also included and 4 reference articles from the latest review article.
Results: After an evaluation of the articles identified in the primary search, 3 relevant reviews and 6 original studies were included. The original studies were 1 case- control study, 3 cohort studies and 1 twin study. They all had the main goal to explore the association between respiratory tract infections in early childhood, and the risk of development of asthma and wheeze in childhood. Conclusion: The conclusion in most of the identified studies indicates that respiratory viral infections during infancy increases the risk of asthma in genetically susceptible children, especially lower respiratory tract infections with respiratory syncytial virus (RSV) and rhinovirus (RV).