Hypersensitivity Pneumonitis Due to Contamination of an Air Conditioner

Abstract

In four of 27 office workers, symptoms of intermittent chills, fever and dyspnea, or progressive dyspnea alone developed. Pulmonary-function studies indicated restrictive and diffusion defects, and x-ray examination demonstrated diffuse nodular infiltrates in all four patients. Examination of their environment revealed contamination of the air-conditioning system with a thermophilic actinomycete known to cause a hypersensitivity pneumonitis such as farmer's lung. Serum specimens of all patients contained high titers of rheumatoid factor and precipitating antibodies against the offending organism. Inhalation of the antigen by one of the ill workers during an asymptomatic period reproduced all clinical features of the disorder. Treatment with steroids and subsequent avoidance of exposure resulted in complete recovery. Hypersensitivity pneumonitis should be suspected in cases of interstitial pneumonitis, even in the absence of clear-cut contact with organic dusts.