This disease is caused by Histoplasma capsulatum. This is a non-capsulated, dimorphic fungus. The spores of this fungus can survive in the soil for a number of years. The survival of the spores is enhanced by soil that is enriched by bat or bird droppings.
Histoplasmosis has a world-wide distribution. However it is commonly seen in the USA especially in Ohio and the Mississippi river valley.
The infection is acquired by inhalation of the spores.
Last reviewed 01/2018