• A common interstitial lung disease caused by hypersensitivity reactions of pulmonary alveoli after inhalation of and sensitization to environmental antigens of microbial, animal, or chemical sources. The disease is characterized by lymphocytic alveolitis and granulomatous pneumonitis.
  • A form of alveolitis or pneumonitis due to an acquired hypersensitivity to inhaled antigens associated with farm environment. Antigens in the farm dust are commonly from bacteria actinomycetes (saccharopolyspora and thermoactinomyces), fungi, and animal proteins in the soil, straw, crops, pelts, serum, and excreta.
  • Conditions in which inhalation of organic dusts results in hypersensitivity reactions at the alveolar level, associated with the production of precipitins.
  • Systemic and pulmonary reactions resulting from inhalation of dust from moldy hay, threshing dust, or moldy straw, by persons who have become hypersensitive to antigens in the dust; most often associated with inhalation of spores of micromonospora faeni or thermoactinomyces vulgaris.