Causes, Incidence and Risk Factors Histoplasmosis is caused by a fungus in central and eastern U.S., eastern Canada, Mexico, Central America, South America, Africa, and Southeast Asia.
Most cases are mild or asymptomatic .
Acute pulmonary histoplasmosis may occur in epidemics. In disseminated disease, the infection is spread to other organs of the body from the lungs via the blood stream. The liver and spleen are usually enlarged, and all body organs can be involved. Ulcerations of the mouth or gastrointestinal tract may occur. Risk factors are travel or residence the central or eastern U.S. and exposure to the droppings of birds and bats.