Children with runny noses are at less risk of developing asthma

Early childhood infectious diseases and the development of asthma up to school age: a birth cohort study

The protective effect of childhood infections [Editorial]

Repeated viral infections early in life may reduce the risk of developing asthma up to school age by stimulating the child's immune system, finds a study in this week's BMJ.

Researchers in Germany followed a group of 1,314 children at regular intervals from birth to the age of 7 years to investigate the association between different types of early childhood infections and the subsequent development of asthma. Among other questions, parents were asked whether their child had "a wheezy or whistling noise while breathing" since the previous follow up.

They found that a child with two or more episodes of runny nose before the age of 1 year was at half the risk of having asthma diagnosed by the age of 7 as were children with one or less episodes. Similarly, having one or more herpes-type viral infection before the age of three years showed an inverse relation with the development of asthma by the age of 7. However, repeated lower respiratory tract infections in the first three years of life showed a positive association with wheeze up to the age of 7 years, suggesting that children already predisposed to asthma might be more likely to develop these type of infections.

Our results suggest that repeated viral infections other than lower respiratory tract infections early in life may stimulate the immature immune system, thereby reducing the risk for the development of asthma up to school age, conclude the authors.

With increasing numbers of effective vaccines, antiviral treatments, and antibiotics and with increasing affluence, how can we prevent the continued rise in allergy and asthma? ask researchers at Imperial College School of Medicine, in an accompanying editorial. Knowing exactly which "dirt" provides the best education for the immune system and how to mimic its effects in a cleaner environment seems to be the key to reversing the rise in atopic diseases, they conclude.

Contacts:

[Paper]: Sabina Illi, Research Assistant, University Children's Hospital, Munich, Germany. Email: sabina.illi@kk-i.med.uni-muenchen.de

[Editorial]: Sebastian Johnston, Professor of Respiratory Medicine, Imperial College School of Medicine at St Mary's, London, UK. Email: s.johnston@ic.ac.uk