Hypersensitive lung disease due to avian antigens.

Five patients, three exposed to budgerigars (parakeets) and two to chickens, had immunological lung reactions. A Type III hypersensitivity response likely accounts for the pulmonary alteration. The inflammatory exudate accumulates within the alveolar walls and adjacent lobular septa. Radiologically, this is manifested as reticular linear densities and/or multiple small nodules, the interstitial pattern. With spillage into the distal air spaces, an acinar pattern emerges. As this disease is reversible in its early stages, increased awareness and proper management may lead to a reduction in the number of patients who are subsequently diagnosed as having "idiopathic pulmonary fibrosis".