Key Facts
- The vast majority of histoplasmosis occurs in the states surrounding the Ohio and Mississippi river valleys covering a large area of the Midwest. It has also been found in parts of Central and South America, Africa, Asia and Australia.
- Histoplasmosis is usually acquired by breathing fungal spores from soil that has been contaminated by bird or bat droppings. It is not contagious (not spread from person to person).
- Most histoplasmosis infections have mild or no symptoms that do not require treatment.
- Patients with weakened immune systems or underlying respiratory disease are more likely to develop a severe form of histoplasmosis that may become chronic or even life-threatening.
How Histoplasmosis Affects Your Body
You get histoplasmosis by inhaling microscopic fungal spores that are released into the air by activities that disturb contaminated soil. Once inhaled, if the person has a healthy immune system, the fungus can cause mild symptoms and lead to lung infection or pneumonia. However, in infants and people with compromised immune systems, the disease can spread throughout the body, including the mouth, liver, central nervous system, skin and adrenal glands. Known as "disseminated histoplasmosis," this is extremely dangerous and, if left untreated, can be fatal.
Who Is at Risk?
Most people who live in an area where Histoplasma is present have been exposed. The fungus usually remains in the body and may never cause a problem or just cause a mild reaction. It is people who come in contact with large amounts of bird or bat droppings, that are more likely to develop an infection. Farmers, pest control workers, poultry keepers, construction workers and landscapers are some occupations that may expose workers to spores and can increase the likelihood of contracting histoplasmosis.
Anyone with a weakened immune system is also more likely to develop severe histoplasmosis. Some things that may compromise your immune system and make your more susceptible are:
- HIV/AIDS
- Recipients of an organ transplant
- Immunosuppressive medications
- Tumor Necrosis Factor inhibitors (TNFs), such as infliximab
- Corticosteroids, such as prednisone
- Antirejection medications, such as mycophenolate and azathioprine
- Extremes of age (infants and the elderly.)
Similarly, people with an underlying lung condition may develop a chronic form of histoplasmosis.
Reviewed and approved by the American Lung Association Scientific and Medical Editorial Review Panel.
Page last updated: November 20, 2023
