Acute histoplasmosis. Description of an outbreak in northern Louisiana.

An outbreak of acute histoplasmosis occurred in northern Louisiana in September 1977. All six men who cleared a field of bamboo cane known to be a blackbird roosting site were affected. All had clinical and roentgenographic findings of acute pulmonary histoplasmosis, and all recovered. Seroconversion or fourfold rise in antibody to Histoplasma capsulatum yeast--or mycelial-form antigens were demonstrated in five. Immunodiffusion testing showed that all six patients developed H capsulatum M bands, and two developed H bands specific for active infection. The H capsulatum was isolated from the soil in the cane field. This is the first report of an outbreak of histoplasmosis in Louisiana and the first known isolation of H capsulatum from Louisiana soil.