Farmer's Lung: A Diagnostic Challenge For the Family Physician.

Farmer's Lung is a respiratory disease caused by inhalation of microspores that grow in warm, damp vegetable material. Although the disease has been widely recognized in many countries, there are only 11 case reports published in Canada. The incidence is likely significant in many rural areas of this country. Inhalation of the microspores produces an allergic reaction in the alveoli of the lung (Arthus Type III). The symptoms are usually dry cough, dyspnea, but little wheezing. Signs are fever, and crackling rales. Antibody precipitins to specific microspores are usually present. Chest X-rays may show miliary lesions and later pulmonary fibrosis. The acute attack is treated with steroids, and prevented by avoiding exposure to mouldy vegetable material. The family physician can diagnose Farmer's Lung early, and thus prevent serious complications.