Histoplasmosis is an infection caused by a fungus called Histoplasma that people get by breathing in its spores, usually from soil containing bird or bat droppings.
What it is
Histoplasmosis mainly affects the lungs and can range from no symptoms at all to a pneumonia-like illness with fever, cough, and chest discomfort. In some people, especially those with weakened immune systems, the infection can spread from the lungs to other organs (disseminated histoplasmosis), which can be severe or even life-threatening if not treated.
How people get it
The fungus lives in soil enriched with bird or bat droppings, and infection happens when activities like construction, demolition, or cleaning up old buildings or caves stir up dust containing fungal spores that are then inhaled. Histoplasmosis does not spread from person to person or between people and pets; it is acquired only from the environment.
Where it is found
Histoplasmosis occurs worldwide, but in the United States it is especially common in the central and eastern regions, including areas around the Ohio and Mississippi River valleys. It is also found in parts of Central and South America, Africa, Asia, and Australia, where similar environmental conditions allow the fungus to grow.
Symptoms and risk
Many infected people never notice any illness, but when symptoms occur they may include fever, cough, fatigue, chest pain, and sometimes long-lasting respiratory symptoms. People who breathe in a large number of spores or who have weakened immune systems (for example, advanced HIV, certain cancers, or immunosuppressive medications) are at higher risk of severe lung disease or disseminated histoplasmosis.
Diagnosis and treatment
Diagnosis usually involves identifying the fungus or its antigens in body fluids or tissues, often with urine or blood tests, cultures, or microscopy. Mild cases often get better on their own, while more severe or disseminated disease is treated with antifungal medications such as amphotericin B or azole drugs as guided by a clinician.
