This study will test the hypothesis that in preschool children with viral-wheeze, those with atopic pulmonary inflammation will respond to a short course of oral corticosteroids, whereas those with a structurally based vulnerability to wheeze will not.  Serum eosinophil protein X (EPX) and eosinophil cationic protein (ECP) will be used to stratify preschool children into atopic inflammation and non atopic inflammation. Children aged between 18 and 48 months of age presenting with viral-wheeze will be divided into two groups: a) those with presenting serum EPX levels of greater or equal to 40 mg/L and or ECP greater or equal to 20 mg/L and b) those with EPX levels <40 mg/L and/or ECP <20 mg/L. At the next episode of viral wheeze children in both groups will receive either placebo or a short course of oral prednisolone. Outcome will be assessed by parental scoring of respiratory symptoms using a diary card.