Histoplasmosis - acute (primary) pulmonary

Definition

Acute pulmonary histoplasmosis is a respiratory infection caused by inhaling the spores of the dimorphic (exists in two forms) fungus Histoplasma capsulatum. This fungus is commonly found in the soil along river valleys. It gets into the soil mostly from bird and bat droppings. The fungus exists as a mold in nature and transforms into a yeast in the human body.

Causes

Histoplasmosis is caused by a fungus found in the Central and Eastern United States, Eastern Canada, Mexico, Central America, South America, Africa, and Southeast Asia.

Most patients have no symptoms (asymptomatic) or experience a mild flu-like illness and recover uneventfully. Acute pulmonary histoplasmosis may occur in an epidemic, which is a widespread local outbreak of disease. Progressive and chronic disease can also occur, particularly amongst those with impaired immune systems, such as people with HIV.

Risk factors include travel to or residence in the Central or Eastern United States near the Ohio and Mississippi River Valleys), and exposure to the droppings of birds and bats. Having a compromised immune system increases a person's risk for more frequent, symptomatic (causing symptoms), and severe disease.