farmers lung

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farmers lung2017-03-27T23:01:39+00:00

farmers lung

farmers lung image from New Medical Terms



An immunoglobulin G1-mediated form of extrinsic allergic alveolitis or hypersensitivity pneumonitis which occurs in non-atopic individuals who, after repeated exposure to organic dust and fungi become allergic to thermophilic actinomycotic organisms; 90% of patients have antibodies to moldy hay, an ideal growth medium for fungi, in particular, Saccharopolyspora rectivirgula, which have been implicated in farmer’s lung

Clinical findings Rales, cyanosis, fever, dry cough, rhonchi, dyspnoea, beginning 4-8 hours after exposure to stored corn, barley, and tobacco; with time, weight loss

Imaging Normal or diffuse interstitial reticular pattern, occasionally with fine nodular shadows 

Seasonality Attacks of several days duration between May and October–the growing season in the Northern Hemisphere 

Pulmonary function tests Reduced functional lung volumes and impaired gas exchange 

Pathogenesis Immune complex deposition causing a type III hypersensitivity reaction to inhaled thermophilic actinomycetes, especially Saccharopolyspora rectivirgula

Management Corticosteroids

Complications Pulmonary hypertension, right ventricular hypertrophy, failure  

Synonym Farm worker’s lung 


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