ABSTRACT
Wheezing is a very common symptom in infants and preschool children. In a national survey in the USA some 27% of all children under 18 years of age incurring medical costs for asthma were in the 0-4 years age group.1 As discussed more fully in Chapter 1, wheezing is reported in almost 50% of infants before 6 years of age in some surveys. In the USA, a prospective cohort study followed children to 6 years of age and it was found that approximately 20% of all infants had transient wheezing before 3 years of age, an additional 14% of infants had continued to wheeze until 6 years of age, and some 15% had begun to wheeze after 3 years and had continued until 6 years of age.2
Similarly, Young et al3 reported an incidence of wheezing of 50% in Australian infants in the first two years of life, but a lower incidence of about 29% was found in preschool children in the UK4 and 17% by 6-7 years of age in Italy.5 From Australia, Oddy et al6
