Diagnosis History of asthma Chest x-ray or high-resolution CT Skin prick test with Aspergillus antigen Aspergillus precipitins in blood Positive sputum culture for Aspergillus species (or, rarely, other fungi) IgE levels Blood eosinophil count The diagnosis is suspected in patients with asthma or cystic fibrosis with recurrent exacerbations, migratory or nonresolving infiltrates on chest x-ray (often due to atelectasis resulting from mucoid plugging and bronchial obstruction), evidence of bronchiectasis on imaging studies, sputum cultures positive for A fumigatus, or notable peripheral eosinophilia.