Severe viral respiratory illnesses and atopy are risk factors for childhood wheezing and asthma.To explore associations between severe respiratory infections and atopy in early childhood with wheeze and asthma persisting into later childhood.

147 children at high atopic risk were followed from birth to 10years. Data on all respiratory infections occurring in infancy were collected prospectively and viral etiology ascertained. Atopy was measured by skin prick tests at 6months, 2 and 5years. History of wheeze and doctor-diagnosed eczema and asthma was collected regularly until 10years of age.At 10years 60% of the cohort was atopic, 25.9% had current eczema, 18.4% current asthma and 20.4% persistent wheeze. 35.8% experienced ≥one lower respiratory infection (LRI) associated with fever and/or wheeze in year1. Children who had wheezy, or in particular, febrile LRI in infancy and were atopic by 2years, were significantly more likely to have persistent wheeze (RR3.51; 95%CI 1.83-6.70; p<0.001) and current asthma (RR4.92; 95%CI 2.59-9.36; p<0.001) at 10years.

Severe viral respiratory infections in infancy and early atopy are risk factors for persistent wheeze and asthma. The strongest marker of the asthmatogenic potential of early life infections was concurrent fever.

The occurrence of fever during respiratory illnesses is an important marker of risk for wheeze and asthma later in childhood, suggesting it should be measured in prospective studies of asthma aetiology.