Acute pulmonary disease of farmers associated with threshing. It is a form of hypersensitivity – alveolitis - caused by exposure to moldy hay or crops. It usually occurs between October and May. The causative microorganisms include Micropolyspora faeni, Thermoactinomyces vulgaris, T. Sacchari, T. Candidus, and T. Viridis. It is characterized by cough, dyspnea, malaise, chills, myalgia, fever a few hours after exposure, cyanosis, tachyardia, tachypnea, and diffuse rales on both lung fields. The symptoms appear suddenly a few hours after the exposure and disappear several hours to a few days later. The condition affects workers of any age, usually males.