Outbreak of hypersensitivity pneumonitis in an industrial setting.

Symptoms consistent with hypersensitivity pneumonitis developed in several workers in two multistory buildings in an industrial complex. A health questionnaire survey was conducted to determine the extent of the problem. Eighty-seven percent of the population of 1050 employees completed the health questionnaire. Serological testing identified 152 positive precipitin reactors to the fungus Aureobasidium pullulans; 115 reactors were symptomatic. The clinical and laboratory features at the time of the acute illness and during four years of follow-up are described. The agent, A pullulans, was identified as a contaminant of the heating-cooling ventilation units containing open waterspray chambers. Control was accomplished by replacement of the ventilation systems. A secondary source of antigen was found to be corrugated cardboard. Some sensitized employees required removal from work exposure to corrugated cardboard to prevent recurrent symptoms.