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

This article discusses the Hygiene Hypothesis. Researchers from the University Children's Hospital in Munich analysed data from 1300 children born in 1990. Children who had at least 2 mild virus infections before their 1st birthday were only half as likely to be diagnosed with asthma when they were seven, compared with children who had been ill once or not at all. BMJ 2001:322:390-5.