Agricultural disorders of the lung.

Agricultural workers are at risk for developing many respiratory tract disorders. Crop production disorders include chronic bronchitis, asthma, organic dust toxicity syndrome, chemical poisoning, farmer lung, and silo-filler disease. Livestock production disorders include toxic manure poisoning (dung lung) and several zoonoses. Radiographic manifestations can be classified into three patterns: (a) normal findings, characteristic of chronic bronchitis, asthma, or organic dust toxicity syndrome; (b) acute diffuse interstitial or alveolar pattern, characteristic of farmer lung, silo-filler disease, dung lung, and chemical poisoning; and (c) chronic interstitial pattern in the upper lobes (farmer lung) or lower lobes (silo-filler disease, paraquat poisoning). Differential diagnosis is aided by knowledge that most of these disorders have a seasonal presentation. Zoonoses generally exhibit focal areas of consolidation in the lung: The type of splenic calcification, presence of mediastinal or hilar adenopathy, and development of bronchiectasis are additional findings useful in differentiating these rare infections.