Abstract

Asthma is a disease with significant and universal morbidity. The increasing prevalence of asthma has no clear explanation, but it is especially due to environmental factors. The causes of asthma are mixed and include genetic and environmental factors. Among the later, an important role seems to have viral and bacterial respiratory infections. Studies have shown a strong association between asthma and the common respiratory viral infections caused by respiratory syncytial virus, adenoviruses, coronaviruses, influenza viruses, and rhinoviruses. It is not clear whether the viral infection is inducing asthma or the association is caused by common predisposing factors for viral infection and asthma. An important role in the aetiology of asthma is currently for typical bacteria. It has been shown that children with asthma have an aberrant immune response to typical pathogenic bacteria in infancy. The mechanisms by which respiratory tract infections can cause asthma are multiple: bronchial hyperresponsiveness, altered neural control mechanisms, changing the geometry of the airways and bronchial inflammation. The viral infections and atypical bacteria are involved in triggering exacerbations in patients with asthma. There is research showing the role of typical bacteria in exacerbating wheezing in children with asthma. In conclusion, the association of respiratory tract infections with asthma is beyond doubt; it remains only to elucidate the precise mechanisms by which they are interrelated.