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a systemic fungal disease caused by inhalation of dust contaminated by Histoplasma capsulatum; it is not transmitted from one person to another. It is particularly common in rural areas of the midwestern United States, but is worldwide in distribution, including in urban areas. The infection begins in the lungs and may spread to other organs; it is usually asymptomatic but may cause acute pneumonia, disseminated reticuloendothelial hyperplasia with hepatosplenomegaly and anemia, or an influenzalike illness with joint effusion and erythema nodosum. Reactivated infection involves the lungs, meninges, heart, peritoneum, and adrenals in that order of frequency. On x-ray the lungs may resemble tuberculous lungs. The preferred drug for treatment of histoplasmosis is amphotericin b. In the USPHS/IDSA Guidelines for the Prevention of Opportunistic Infections in Persons with Human Immunodeficiency Virus, persons with HIV infection are cautioned to avoid activities associated with increased risk of exposure to Histoplasma capsulatum, such as cleaning chicken coops, disturbing soil underneath bird roosting sites, or exploring caves.
ocular histoplasmosis disseminated choroiditis resulting in scars in the periphery of the fundus near the optic nerve, and characteristic disciform macular lesions; Histoplasma capsulatum is implicated strongly as the causative agent.