A large histoplasmosis outbreak among high school students in Indiana, 2001.

Background: A histoplasmosis outbreak occurred in an Indiana high school in November-December 2001.

Methods: To describe the risk factors for this outbreak, we conducted a cohort study of all available students and staff (N = 682) and an environmental investigation.

Results: Of the 523 (77%) persons who displayed serologic evidence of recent Histoplasma capsulatum infection, 355 (68%) developed symptoms consistent with acute pulmonary histoplasmosis.