What is the role of histoplasma chorioretinitis in the ocular manifestations of HIV infection?

Updated: Jun 12, 2019
  • Author: Robert A Copeland, Jr, MD; Chief Editor: Andrew A Dahl, MD, FACS  more...
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Answer

Answer

H capsulatum is a small, gram-positive, mycelial dimorphic fungus, approximately 3-5 mm in diameter. The organism is endemic in the central and eastern United States, particularly the Mississippi-Ohio River Valley, as well as Central America, Asia, Turkey, Israel, and Australia. The organism enters the body via the respiratory tract by inhalation of spores.

Acute histoplasmosis tends to be benign and self-limiting, mostly affecting the pulmonary system. The infection may be subclinical.

In disseminated histoplasmosis, the organism spreads hematogenously, producing lesions throughout the body, especially in the reticuloendothelial system of the liver, spleen, lymph nodes, and bone marrow. Risk factors contributing to the dissemination of infection include a defective immune system, such as that seen in AIDS or malignancies; an immature immune system in infants; or iatrogenic immunosuppression. Disseminated histoplasmosis is uncommon in immunocompetent adults.

Disseminated histoplasmosis has a high mortality in AIDS patients. This disease tends to have a fulminant course, usually complicated by disseminated intravascular coagulation.


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