Histoplasmosis

Histoplasma capsulatum (Hc) is a dimorphic fungus present worldwide in pockets of endemicity, particularly associated with river valleys. The endemic regions in the United States include the Ohio and Mississippi River valleys and the southeastern states. It is a soil-based fungus, and when it is disturbed, the conidia become airborne and can be inhaled. Often, the infections are asymptomatic, but a granulomatous inflammation results in pulmonary disease akin to pulmonary tuberculosis. In immunocompromised patients, histoplasmosis can become disseminated and lead to considerable morbidity and mortality. It is rarely seen in immunocompetent patients.