Histoplasmosis is an infection that occurs from breathing in the spores of the fungus Histoplasma capsulatum.
Ohio River Valley fever; Fibrosing mediastinitis
Histoplasmosis is a fungal infection. It occurs throughout the world. In the United States, it is most common in the southeastern, mid-Atlantic, and central states.
Histoplasma fungus grows as a mold in the soil. You may get sick when you breathe in spores produced by the fungus. Soil that contains bird or bat droppings may have larger amounts of this fungus. The threat is greatest after an old building is torn down, or in caves.
This infection can occur in people with a normal immune system, but having a weakened immune system increases the risk of getting or reactivating this disease. Very young or very old people, or those with AIDS, cancer, or an organ transplant have more severe symptoms.
People with chronic (long-term) lung disease (such as emphysema and bronchiectasis) are also at higher risk for a more severe infection.
Most people have no symptoms, or only have a mild, flu-like illness.
If symptoms do occur, they may include:
- Fever and chills
- Cough and chest pain that gets worse when breathing in
- Joint pain
- Mouth sores
- Red skin bumps, most often on the lower legs
The infection may be active for a short period of time, and then the symptoms go away. Sometimes, the lung infection may become chronic. Symptoms include:
- Chest pain and shortness of breath
- Cough, possibly coughing up blood
- Fever and sweating
In a small number of people, histoplasmosis may spread throughout the body, causing irritation and swelling (inflammation) in response to the infection. This is called disseminated histoplasmosis. Symptoms may include:
- Chest pain from swelling in the lining around the heart
- Headache and neck stiffness from swelling in the covering of the brain (meninges) and spinal cord
- High fever
Exams and Tests
Histoplasmosis is diagnosed by:
- Biopsy of the lung, skin, liver, or bone marrow
- Blood or urine tests to detect histoplasmosis proteins or antibodies
- Cultures of the blood, urine, or sputum (this test provides the clearest diagnosis of histoplasmosis, but results can take 6 weeks)
To help diagnose this condition, your health care provider may do a:
- Chest CT scan
- Chest x-ray
- Spinal tap to look for signs of infection in cerebrospinal fluid (CSF)
Most of the time, this infection goes away without treatment.
If you are sick for more than 1 month or are having trouble breathing, your provider may prescribe medicine. The main treatment for histoplasmosis is antifungal drugs.
- Antifungals may need to be given through a vein, depending on the form or stage of disease.
- Some of these medicines can have side effects.
Sometimes, long-term treatment with antifungal drugs may be needed. You may need to take these medicines for up to 1 to 2 years.
The outlook depends on how severe the infection is, and your general health condition. Some people get better without treatment. An active infection will usually go away with antifungal medicine, but the infection may leave scarring inside the lung.
The death rate is higher for people with untreated disseminated histoplasmosis who have a weakened immune system.
Scarring in the chest cavity may put pressure on the:
- Major blood vessels carrying blood to and from the heart
- Esophagus (food pipe)
- Lymph nodes
Enlarged lymph nodes in the chest may press on body parts such as the esophagus and blood vessels of the lungs.
When to Contact a Medical Professional
Call your health care provider if you live in an area where histoplasmosis is common and you develop:
- Flu-like symptoms
- Chest pain
- Shortness of breath
While there are many other illnesses that have similar symptoms, you may need to be tested for histoplasmosis.
Histoplasmosis may be prevented by reducing exposure to dust in chicken coops, bat caves, and other high-risk locations. Wear masks and other protective equipment if you work in or go into these environments.
Deepe GS Jr. Histoplasma capsulatum. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 8th ed. Philadelphia, PA: Elsevier Churchill Livingstone; 2014:chap 265.
Kauffman CA. Histoplasmosis. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 340.
Reviewed By: Jatin M. Vyas, MD, PhD, Associate Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.