Chronic pulmonary histoplasmosis is a long-term respiratory infection caused by breathing the spores of the fungus, Histoplasma capsulatum.

See also:

• Acute pulmonary histoplasmosis
• Disseminated histoplasmosis
• Skin lesion of histoplasmosis

Histoplasma capsulatum is a fungus found in the soil of the central and eastern United States (especially Mississippi and Ohio river valleys), eastern Canada, Mexico, Central America, and South America.

The infection occurs when a person breathes in the reproducing parts of the fungus, called spores. Those who have a healthy immune system usually do not have symptoms, or only mild ones.

This "acute" infection does not last, but can leave a person with small scars (granulomas). These scars can be difficult to distinguish from tumors in the lung.

However, the infection can cause severe illness right away, or redevelop years after the first exposure, if a person's immune system is weakened by:

• Cancer
• Chemotherapy
• Immune-suppressing drugs
• HIV infection

Risk factors for chronic pulmonary histoplasmosis include:

• Living in or traveling to central or eastern United States
• Exposure to soil or particles contaminated with droppings of chickens, bats, or blackbirds
• Pre-existing COPD
• Weakened immune system, such as in people who have AIDS