histoplasmosis /his′tōplazmō″sis/ [Gk, histos + plasma + osis, condition] , an infection caused by inhalation of spores of the fungus Histoplasma capsulatum. Most cases are asymptomatic. Individuals who experience symptoms are usually either immunocompromised or have been exposed to a high inoculum. Primary histoplasmosis is characterized by fever, malaise, cough, and lymphadenopathy. Spontaneous recovery is usual; small calcifications remain in the lungs and affected lymph glands. Progressive histoplasmosis, the sometimes fatal disseminated form of the infection, is characterized by ulcerating sores in the mouth and nose; enlargement of the spleen, liver, and lymph nodes; and severe and extensive infiltration of the lungs. The severe form is treated with amphotericin B, and less severe cases may be treated with ketoconazole. Infection confers immunity. A histoplasmin skin test may be performed to identify people who may safely work with contaminated soil. The disease is most common in the Mississippi and Ohio River Valleys. Also called Darling’s disease.
