Farmer’s Lung

An IgG1-mediated form of extrinsic allergic alveolitis or hypersensitivity pneumonitis that occurs in non-atopic individuals, who, after repeated exposure to organic dust and fungi (e.g., Aspergillus spp.), become allergic to thermophilic actinomycotic organisms; 90% of patients have antibodies to moldy hay, an ideal growth medium for the fungi—Microspora vulgaris, Thermoactinomyces vulgaris and Micropolyspora faeni—that have been implicated in farmer’s lung
Seasonality Attacks of several days' duration between May and October—the growing season in the Northern Hemisphere
Pulmonary function tests Decreased functional lung volumes and impaired gas exchange
Management Corticosteroids
Complications Pulmonary HTN, right ventricular hypertrophy, failure