Light micrograph of stained lung tissue affected by histoplasmosis. Histoplasmosis is a disease primarily affecting the lungs which can develop following inhalation of spores from the fungus Histoplasma capsulatum. In most cases, people are not affected when they inhale these spores, but in some cases develop a fever, cough, and fatigue which typically self-resolve. In rare cases, particularly when patients are immunosuppressed, severe histoplasmosis can develop, and potentially affect almost any part of the body. This can lead to respiratory or bone marrow failure which can be fatal. Antifungal medication is the typical treatment course when necessary.