A 60-year-old woman had had recurrent acute migratory
pneumonias for 9 months. The results of an evaluation, which included tests for serum
precipitins, a transbronchial biopsy, and a bronchial provocation, confirmed a diagnosis of
hypersensitivity pneumonitis caused by an Aspergillus species. The findings from gravity air cultures in the home showed a heavy infestation of mold. The installation of electrostatic dust filters in the return ducts of the central air conditioning system resulted in the lowering of mold colony counts to normal levels. This change in the environment enabled the patient to live at home without having the signs and symptoms of
hypersensitivity pneumonitis, or a need for medication. Thirty months after the electrostatic dust filters were installed, total mold colony counts were still normal, the patient remained free of the signs and symptoms of
hypersensitivity pneumonitis, and serum
precipitins could no longer be demonstrated. The results of a bronchial challenge to Aspergillus species, however, remained positive; these positive results suggest that long-term memory immune mechanisms may play an important role in the pathogenesis of
hypersensitivity pneumonitis and lessen the importance of
precipitins in establishing a diagnosis. We report that electrostatic dust filters may be an effective treatment for patients with
hypersensitivity pneumonitis when avoidance of the causative
antigen cannot be easily and rapidly achieved.