Recurrent exposure to Histoplasma capsulatum in modern air-conditioned buildings.

Background: Between 1989 and 1996, an epidemic of histoplasmosis occurred on a medical school campus. There had been numerous construction projects on the campus that involved previously wooded land and were adjacent to a large bird sanctuary.

Methods: We investigated the epidemic with active surveillance to detect cases, a histoplasmin skin-test survey, inspection of the air-filtration systems of the involved buildings, and cultures of soil samples.