Hypersensitivity Pneumonitis

Introduction Hypersensitivity pneumonitis (HP), also called extrinsic allergic alveolitis, is a respiratory syndrome which contributes a spectrum of granulomatous, interstitial, bronchiolar and alveolar-filling lung diseases. HP was first described by Bernadino Ramazzini, an Italian researcher, who researched in subjects with 52 different professions. He proposed that a repeated exposure to particles with diameter less than 5 μm can reach the alveoli and trigger an immune response. The most at risk professional categories are farmers and breeders . HP was first described in 1932. There was an outbreak of illness in 10 employees of a sleepers company in Michigan. These people developed dyspnea, productive cough, night sweats, and weight loss after resuming of work. Their labor barked stripes from maple logs and about 30% of workers developed these symptoms. Their chest radiographs showed increased opacities at peribronchial and perihilar areas and poorly defined nodules in the lower lungs. There was another similar outbreak in 36 of 800 employees at a nearby sawmill, which most of its logs were maple. Investigators noticed that there was black dust lying beneath the bark. It was isolated a fungus called Cryptostroma corticale. They supposed that this disease was an allergic reaction to its aerosolized spores .