Infection by a fungal organism, Histoplasma capsulatum. This organism is found in soil, especially in areas contaminated by bird or bat droppings. Sometimes it is called “spelunker’s disease,” and it seems to be commoner in the Mississippi River valley than in other areas of the United States. Persons who contract this organism may not even know it, as they may have a self-limited, mild, flu-like syndrome. As with many infections, histoplasmosis can of course be more severe and even disseminated in persons who are immunocompromised. Transmission is primarily respiratory, and the primary target is the lungs, where it can cause non-progressive granulomas. It is quite rare in the larynx.