[Association between asthma and viral infections].

Viral respiratory infections are the factor most frequently associated with asthma (independently of phenotype, age, and phase of the natural history of asthma during which the infection occurs) and there is a strong temporal association between viral respiratory infections and acute obstructive/asthmatic episodes. Nevertheless, the role of viral infections in the pathogenesis of asthma remains poorly characterized. The factors that could explain this association are heterogeneous and sometimes contradictory. The four main causative mechanisms implicated in the association between viral respiratory infections and the subsequent development of asthma or wheezing in children are alterations in airway function and size, dysregulation (congenital and acquired) of airway tone, alterations in the immune response to infections, and the genetic variants involved in immune response. These mechanisms should be taken into account in future preventive and therapeutic strategies.