Histoplasmosis is commonly associated with exposure to bird or bat droppings and is endemic in which region?

• A. Central and Eastern United States
• B. Pacific Northwest
• C. Northern Europe
• D. Sub-Saharan Africa

Answer: (A)

Histoplasmosis is caused by Histoplasma capsulatum, a fungus that grows in soil enriched with bird or bat droppings. Inhalation of the airborne spores after disturbing such soil leads to infection. It is most classically endemic in the central and eastern United States, especially the Ohio and Mississippi River valleys, so exposure histories often involve activities like spelunking, cleaning chicken coops, or being in areas with bat guano in that region. The other regions listed are not the typical endemic zones for histoplasmosis, making the central and eastern United States the best match.