[The wheezing child and pediatric respiratory infections].

Given that the respiratory and immunity systems are still in development up to the age of 3 years, viral infections and exposure to environmental factors such as passive smoking in babies and young children may alter these systems, so favouring the development of allergic rhinitis and asthma. This may explain the correlation between viral respiratory infections or exposure to environmental factors and later development of wheezing and asthma. Prevention of respiratory infections may thus reduce the risks of pneumonopathy in the long term. For greatest efficacy however, the preventative measures must be in place before the age of 3 years, i.e. before lung development has been completed.