Hypersensitivity pneumonitis is reviewed with regard to causative agents, occupations, industries, and workers at risk, epidemiology, pathology, clinical description and diagnostic criteria, methods of prevention, and research needs. Hypersensitivity pneumonitis is defined as a diffuse predominantly mononuclear inflammation of the lung parenchyma resulting from sensitization and recurrent exposure to inhaled organic dusts. Dusts causing the disease include moldy fodder in farmer's lung, moldy sugar cane in bagassosis, bird droppings or other avian proteins in bird handler's lung, and mold spores in maple bark stripper's disease. Diagnosis is made from a combination of symptoms, physical findings, x-ray abnormalities, pulmonary function and immunological testing. Patients with recurring bouts of influenza like pneumonitis or active interstitial lung disease and exposure to a causative agent are suspect for the disease. Clinical and laboratory symptoms have disappeared when the patient was removed from the allergen. However, prolonged exposure can cause irreversible lung damage. Hypersensitivity secondary to contaminated forced air and humidification systems was noted by the author to be increasing in occurrence. Priorities for study include pathogenetic cognizance, animal model development, immunochemical analysis of antigens, and comprehensive determination of the prevalence and natural history of the diseases.
Occupational Respiratory Diseases. J. A. Merchant, Editor; Division of Respiratory Disease Studies, Appalachian Laboratory for Occupational Safety and Health, NIOSH, U.S. Department of Health and Human Services, DHHS (NIOSH) Publication No. 86-102