pulmonary disorders
Hypersensitivity Pneumonitis
Etiology of Hypersensitivity Pneumonitis
Over 300 antigens have been identified as triggers for hypersensitivity pneumonitis. Antigens encountered through farming, birds, and water contamination account for about 75% of cases. ); farmer’s lung, caused by inhalation of hay dust containing thermophilic actinomycetes, is the prototype. Substantial overlap exists between hypersensitivity pneumonitis and Chronic Obstructive Pulmonary Disease (COPD) in farmers, in whom chronic bronchitis is far more common, occurs independently of smoking status, is linked to thermophilic actinomycete exposure, and leads to findings similar to those of hypersensitivity pneumonitis on diagnostic testing. 