[Extrinsic allergic alveolitis in agricultural environment]

The term extrinsic allergic alveolitis involves a group of interstitial and alveolar lung diseases with an immunoallergic mechanism. These diseases are associated with chronic inhalation of usually organic particles and therefore encountered almost exclusively in an agricultural environment. The most frequent and best known of them is the farmer's lung disease and therefore is largely described by the authors. Specific points concerning pigeon breeder's disease and cheese worker's disease, are also reviewed since they are quite frequently observed in France. The diagnosis is difficult because the radiological and functional abnormalities are transient and the signs of immunization in serum and alveoles are unspecific. This problem is developed here, and a practical diagnostic approach is suggested. Treatment is essentially preventive and includes modifications of the working tools and work conditions in order to reduce exposure to airborne pathogenic antigens.