Hypersensitivity pneumonitis (HP)
Hypersensitivity pneumonitis, also known as extrinsic allergic alveolitis, is a delayed allergic response that affects the lung parenchyma, particularly the alveoli, terminal bronchioles, and alveolar interstitial space. Such a reaction is the result of a patient's frequent and protracted inhalation of various organic airborne particles or other substances to which he or she is hypersensitive and highly responsive, mainly organic dust of animal or vegetable source, with chemicals coming in a close second. Recurrent exposure to particles tiny enough (diameter 5 m) to enter the alveoli and activate an immunological response is required in this syndrome, which was initially described by Italian scientist Bernardino Ramazzini in different occupations.
Workers in workplaces or environments contaminated by organic dust of diverse origins, primarily gardeners or breeders, are the most at threat professional categories. Avian dust, fungus, paint catalysts, sugar cane dust, hay sand, mushrooms, rat or gerbil urine, tobacco, air-conditioning system water, maple bark dust, redwood bark sand, beer brewing, cork dust, plastic residues, epoxy matrix, enzyme detergents, wheat mold or dust are all possible causes. The intensity of symptoms, clinical manifestations, and prognosis of the syndrome vary widely based on the causative factor, length of exposure, host variables, and antigen features. Hypersensitivity pneumonitis can usually be corrected quickly by finding and eliminating the causative substances, which can be found in a variety of places, including the home, office, and recreational situations.