Chronic hypersensitivity lung disease with recurrent episodes of hypersensitivity pneumonitis due to a contaminated central humidifer.

A child with a 4-year history of acute and chronic respiratory symptoms of unknown aetiology was investigated for hypersensitivity pneumonitis. Lung disease due to inhalation of material from a contaminated central humidifier was suggested by the clinical history, the presence of precipitating antibodies in the serum against the humidifier water, a pulmonary response to challenge with the humidifier water, and marked improvement after removal of the humidifier. No fungi were cultured from the humidifier nor were antibodies against a number of fungal antigens identified by radioimmunoassay inhibition techniques. Antigenic material was found in the humidifier water and the household water prior to its reaching the humidifier. This antigenic material was not found in laboratory tap water supplied from the same general source (Lake Michigan) but from a different pumping station. Three of the child's siblings gave histories suggestive of a single concurrent episode of acute hypersensitivity pneumonitis and one sibling had a history suggestive of chronic hypersensitivity lung disease. No association could be found between HLA-haplotypy and disease in the patient and the siblings.