Effects of upper versus lower respiratory infections on the induction of atopic asthma.

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Asthma is more common now in developed countries than it was 20-30 years ago. Many fewer children have asthma in developing countries and there does not appear to have been the same increase in asthma in recent years. Children in developed countries tend to have fewer respiratory infections and recent studies suggest that this may be partly responsible for the increase in asthma. An understanding of why asthma has increased in developed countries may lead to strategies to prevent asthma. In order to understand the role that respiratory infections may play in the induction of asthma, it is necessary to study babies from birth, documenting each respiratory inflection and monitoring their diet. In a recent large study we have shown that parental reports of common colds and chest infections do influence how many children have asthma at age 6. Also in this study, breast feeding for at least 4 months seemed to be protective against developing asthma. However, we were not able to verify how many infections the children in that study actually had. We are currently studying a population of 236 infants, all of whom are at high risk of developing asthma and allergies. At the end on November 1998, 163 of these infants had reached one year of age. During the first year of life, these infants had a total of 669 respiratory infections, with individual babies having between 0 and 11 infections. We now plan to monitor these children until they turn 5, when we will determine how many have asthma and allergies. In this way we will be able to determine whether children who have more respiratory infections early in life are more or less likely to have asthma and allergies at 5 years of age. We will also be able to tell whether breast-feeding is able to decrease the chance of developing asthma and allergies.