Histoplasmosis

Abstract

Histoplasmosis is caused by a dimorphic fungus and is manifest by epidemics of infection or endemic infection with a spectrum from subclinical illness to progressive disseminated disease. Diagnosis is best made by visualization of the yeast in tissue or by culture, although detection of the fungal antigen in urine specimens is very useful as well. Histoplasma capsulatum, with a heavy inoculum, may cause acute pulmonary infection in the normal host, resulting in fever, hypoxia, and pulmonary infiltrates. Opportunistic histoplasmosis appears as chronic pulmonary histoplasmosis in those with a structural defect in the lung (emphysema) and as disseminated histoplasmosis in patients with cellular immune deficiency (immunosuppressants, AIDS). Itraconazole is the drug of choice for both, except in life-threatening infection when amphotericin B is indicated.