FA 2019 P. 661 Hypersensitivity Pneumonitis is a mixed type III/IV hypersensitivity reaction to an antigen in the environment. Commonly seen in farmers and people exposed to birds. Presents with Dyspnea, Cough, Chest tightness, headache. It is reversible in the early stages if the allergen is removed.
A type of hypersensitivity pneumonitis associated with animal exposure is bird fancier’s lung, in which the major antigens are proteins in avian serum, feces, and feathers, including bloom, the waxy powder coating them (18). Pigeons and parakeets, including budgerigars (a type of parakeet), are the birds most commonly implicated, but poultry, finches, doves, canaries, and other birds also have caused the disease. Exposure to live birds is not necessary to produce hypersensitivity pneumonitis: the illness has resulted from using feather pillows and duvets (19), being exposed to a wreath made from the feathers of a dead pet bird (20), and laundering a pigeon keeper’s overalls (21). Other examples of animal proteins that are known to have caused the disease when inhaled include proteins from the dust of mollusk shells used to make buttons (22) and from animal fur used in garment manufacture