Outbreak of acute pulmonary histoplasmosis in members of a wagon train.

In August 1980, an outbreak of acute pulmonary histoplasmosis occurred among participants in a wagon train as it traveled through eastern Tennessee. Of the 85 people on the train 69 (81 percent) had evidence of infection with Histoplasma capsulatum. Fifty-four people had symptomatic disease. The source of infection was traced to the site of a former winter blackbird roost in Charleston, Tennessee, that had been partially cleared five years earlier to make a park. Fourteen of 25 soil samples from this site were culture-positive for H. capsulatum. This is the first reported outbreak to involve a large migrant group. The outbreak is unusual in that exposure occurred without excavation, construction or tree-cutting at the site.