Understanding Histoplasmosis: Causes, Symptoms, and Care
Updated: 1 day ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026
Quick Answer
Histoplasmosis is a fungal lung infection caused by breathing in spores of Histoplasma capsulatum, common in the Ohio and Mississippi River valleys and where bird or bat droppings enrich the soil. [1] [2] It is often mild or symptomless but can cause flu-like illness, long-term lung problems or spread to other organs. [1] Antifungal medicines treat symptomatic or high-risk people. [1] [2]
What the research says
Exposure to the fungus is more widespread than the classic "Ohio Valley" map suggests. A global systematic review of 224 studies (171 skin test surveys and 44 serological surveys) spanning 66 countries and all 6 World Health Organization regions found that the prevalence of infection exceeded 10% in studies from the Americas, Southeast Asia, and Africa. The authors note that most studies used nonrepresentative sampling (Brooks et al., Open Forum Infectious Diseases, 2025 [4]).
A less toxic form of amphotericin B worked better in severe disease linked to AIDS. In a randomized, double-blind trial of 81 patients with AIDS and moderate to severe disseminated histoplasmosis, clinical success was 88% (45 of 51) with liposomal amphotericin B versus 64% (14 of 22) with conventional amphotericin B. Kidney toxicity occurred in 9% versus 37% of patients, infusion-related side effects in 25% versus 63%, and one patient versus three died during induction (Johnson et al., Annals of Internal Medicine, 2002 [3]).
Antigen tests are the best tool for early diagnosis of disseminated disease, but access is scarce. A 2026 review reports that commercial Histoplasma antigen tests are highly sensitive and specific, yet limited access worldwide leads to misdiagnosis. Current treatment relies on amphotericin B and itraconazole (Pasqualotto et al., The Lancet HIV, 2026 [5]).
Histoplasmosis is a serious threat for people with HIV. A systematic review prepared for the World Health Organization found histoplasmosis in 22% to 44% of people living with HIV in the studies reviewed, with death rates of 21% to 53%. Resistance to amphotericin B and itraconazole remained low (Dao et al., Medical Mycology, 2024 [6]).
Key Takeaways
What Is Histoplasmosis?
Histoplasmosis, sometimes called "Cave Disease" or "Ohio Valley Disease," is an infection that mainly affects the lungs. The cause, Histoplasma capsulatum, is a dimorphic fungus: it exists as a mold in the environment and changes into a yeast once it enters the warm environment of the human body. [1] Most people who inhale the spores do not get sick. [2] When the amount of fungus is high or the person's immune system is weakened, the infection can take hold.
The infection is grouped into several types based on how long it lasts and how far it spreads. Acute pulmonary histoplasmosis is the most common symptomatic form and feels like a sudden bout of pneumonia. [1] Chronic cavitary histoplasmosis is a long-term form, most often seen in people with emphysema or COPD, that can look like tuberculosis and cause permanent lung damage if it is not managed. [1] The most severe form, progressive disseminated histoplasmosis, occurs when the fungus leaves the lungs and spreads to other organs such as the liver, spleen, and bone marrow. [1] The fungus can also affect the eyes, as in ocular histoplasmosis, or the brain. [1] [2]
Histoplasmosis is one of several fungal infections acquired from the environment. To compare it with others, see our guides to fungal infections (mycosis), blastomycosis, and Valley fever.
What are the symptoms and warning signs of histoplasmosis?
In up to 90% of people, breathing in the fungus causes no symptoms, or the symptoms go away on their own. [1] When symptoms do appear, they usually start 3 to 17 days after exposure. [2] The first signs often resemble the flu or other respiratory infections, which can lead to misdiagnosis, especially in regions where the fungus is not common.
Common symptoms include a persistent cough, fever, chills, headache, fatigue, and chest pain, and some people have muscle aches or joint pain. Some people develop a rash called erythema nodosum, which appears as red bumps on the lower legs. [1] In chronic cases, people may notice weight loss and night sweats, similar to the symptoms of tuberculosis. [1]
Chronic histoplasmosis can also cause a bloody cough and trouble breathing. Disseminated histoplasmosis can affect nearly any part of the body, including the mouth, liver, brain, spinal cord, skin and adrenal glands, and without treatment it is often deadly. [7]
Complications can include acute respiratory distress syndrome (ARDS), inflammation of the tissue around the heart (pericarditis), adrenal insufficiency and meningitis. [7]
Because the symptoms look like those of pneumonia caused by bacteria or viruses, providers often prescribe antibiotics first. Antibiotics do not treat fungal infections. [2] If you live in or recently traveled to an area where the fungus lives and your symptoms do not improve, ask your provider about testing for histoplasmosis. [2]
Call a healthcare professional if flu-like symptoms develop after exposure to bird or bat droppings, especially if you have a weakened immune system. [7]
What causes histoplasmosis, and what environments raise the risk?
The cause of histoplasmosis is inhaling fungal spores. The spores become airborne when soil containing bird or bat droppings is disturbed. Activities such as farming, cleaning out chicken coops, exploring caves, and working on construction or demolition sites raise the risk of exposure. [1]
The fungus thrives in damp soil that is rich in organic material and is also common in pigeon coops, old barns and parks. People more likely to be exposed include farmers, pest control workers, poultry keepers, construction workers, roofers, landscapers and gardeners, miners and cave explorers, demolition workers, and oil and gas extraction workers. [7]
Histoplasmosis is not contagious. It does not spread between people or between people and pets, because it is an environmental infection caught by inhaling spores from the surroundings. [2]
A person who has had histoplasmosis can get it again, although the illness is likely to be milder the second time. [7]
Geographically, the fungus is most common in the Ohio and Mississippi River valleys in the United States. [1] It is also found in Central and South America, Africa, Asia, and Australia. [1] People over 55, infants under one year old, people with weakened immune systems, and those with pre-existing lung conditions such as emphysema or COPD are at higher risk of severe or chronic illness. [1]
Children younger than 2 and adults 55 and older are also described as more likely to get the most serious form, and factors that weaken the immune system include HIV or AIDS, cancer chemotherapy, corticosteroids such as prednisone, tumor necrosis factor (TNF) inhibitors and medicines that prevent transplant rejection. [7]
How is histoplasmosis diagnosed and treated?
Healthcare providers use several methods to diagnose histoplasmosis because the symptoms overlap with many other conditions. Chest X-rays or CT scans are often the first step to look for inflammation or granulomas in the lungs. [1] To confirm the fungus, providers may test blood or urine for specific antigens and antibodies, or test mucus from the lungs. [1] [2] Growing the fungus in a lab (culture) is the best way to confirm the diagnosis, but it can take several weeks. [1] In complex cases, a tissue biopsy or a bronchoscopy may be needed to collect samples directly from the lungs. [1]
Treatment Type | Description |
Observation | |
Antifungals | |
Intravenous Therapy | Amphotericin B is reserved for severe or life-threatening disseminated cases. [2] |
Steroids | Corticosteroids may be used to reduce severe inflammation in the lungs or heart. |
How can you prevent histoplasmosis?
Histoplasmosis risk can be lowered by not disturbing soil or dust where birds or bats live and by wearing an N95 respirator when exposure is likely. [1] Avoid disturbing soil or dust in places where birds or bats live. If your job or hobbies expose you to soil that is likely to contain the fungus, wear an N95 respirator to help filter the air you breathe. [1] If you have a weakened immune system, COPD, or emphysema, ask your provider about extra precautions.
Other steps include hiring a hazardous-waste removal company instead of cleaning up large amounts of droppings yourself, asking an employer about a site safety plan and training, and soaking soil and surfaces with water before digging or cleaning to keep spores out of the air. [7]
What are recovery and the long-term outlook for histoplasmosis?
For most healthy people, the outlook is excellent, and many recover fully without medical treatment. Cleveland Clinic reports that about 96% of people with healthy immune systems survive histoplasmosis with treatment. [1] For people with weakened immune systems, the infection can be life-threatening if it is not treated promptly, and some studies suggest a mortality rate of 25% to 37% in this group. [1] Treatment for chronic or severe cases can last from about 3 months to a year or longer, to clear the infection and prevent a relapse. [2]
Conclusion and Next Steps
Histoplasmosis is manageable when it is identified early. If you live in an area where the fungus is common and you have persistent respiratory symptoms, seek a medical evaluation. For people at higher risk, taking environmental precautions is the best defense against this common but potentially serious fungal infection.
Frequently Asked Questions
Is histoplasmosis contagious?
No. It does not spread from person to person or from pets to people. [2]
Can I get histoplasmosis from my pet bird?
Birds do not pass the disease to people, but their droppings provide the nutrients the fungus needs to grow in soil.
How long does it take to recover?
Mild cases resolve in a few weeks, while severe cases may require months of treatment.
Can histoplasmosis affect the eyes?
Yes. A condition called ocular histoplasmosis can occur and may lead to vision loss. Read more about ocular histoplasmosis.
Is it possible to get histoplasmosis twice?
Yes, reinfection is possible, and a second infection is often milder.
What is the best way to prevent exposure?
Avoid disturbing soil in high-risk areas, or wear an N95 respirator if you must work in those environments.
Does histoplasmosis cause cancer?
No, but it can cause lung nodules that may be mistaken for cancer on imaging tests.
Can children get histoplasmosis?
Yes. Infants under one year old are at higher risk of severe infection. [1]
Is there a vaccine for histoplasmosis?
No, there is currently no vaccine available.
What organs are affected in disseminated histoplasmosis?
It can affect the liver, spleen, bone marrow, and skin. [1]
Can histoplasmosis cause a rash?
Yes. It can cause erythema nodosum, which appears as red bumps on the legs. [1]
Is histoplasmosis the same as the flu?
No, but the symptoms can be very similar.
Do all caves have the fungus?
Not all of them, but caves with bat populations are high-risk areas.
Can I get it from gardening?
Yes, if the soil contains the fungus and is disturbed.
What is the most common medication for treatment?
Can it affect the brain?
Yes. In rare cases it can cause central nervous system histoplasmosis. [2]
Is weight loss a symptom?
Yes, mainly in chronic or disseminated cases. [1]
Can histoplasmosis cause chest pain?
Yes, it is a common symptom of the lung form. [1]
What is a granuloma?
A small area of inflammation that the body creates to wall off the fungus. [1]
Is it common in the UK?
It is uncommon in the UK. Most cases occur in the Americas, Africa, and parts of Asia, [4] [5] although travelers who visit caves or other high-risk places abroad can still be exposed.
Can I die from histoplasmosis?
It is rare in healthy people but can be fatal for people with weakened immune systems. Cleveland Clinic reports that about 96% of people with healthy immune systems survive with treatment. [1]
Should I see a specialist?
Yes. An infectious disease specialist is usually the best provider for this condition.
Can histoplasmosis cause night sweats?
Yes, this is common in chronic cases. [1]
How is the urine test performed?
Can I go to work with histoplasmosis?
If your symptoms are mild, you may be able to, but consult your doctor first.
Is it a seasonal infection?
No. It can be acquired at any time of the year.
Can smoking make it worse?
Lung damage from smoking, such as emphysema or COPD, increases the risk of chronic infection. [1]
What is fibrosing mediastinitis?
A rare complication involving severe scarring in the area between the lungs. [1]
Can it cause confusion?
Yes, if it spreads to the central nervous system.
Is it found in city soil?
It can be, especially near bird roosting areas or construction sites.
Can I get it from a swimming pool?
No. It is a soil-based fungus.
Does it affect the heart?
In rare cases, it can cause inflammation around the heart (pericarditis).
How long do I need to take medicine?
Treatment can range from about 3 months to a year or longer, depending on severity and immune status. [2]
Can it be detected on a regular blood count?
A blood count may show signs of infection, but specific fungal tests are needed for diagnosis.
Is it related to mold in houses?
No. It is a different type of fungus that lives in soil.
Can it cause shortness of breath?
Yes, this is a hallmark symptom of the lung infection.
What is the "Ohio Valley" connection?
The fungus is especially common in the Ohio and Mississippi River valleys of the United States. [1]
Can I get it from eating contaminated food?
No. It is acquired by inhaling spores. [2]
Is it more common in men or women?
Anyone can get it. Risk depends more on exposure (such as farming, construction, or caving) and immune status than on sex.
Can it cause joint pain?
Yes, some people have arthritis-like symptoms during the infection.
What is yeast transformation?
The process in which the fungus changes shape inside the body so that it can survive there. [1]
Can it be mistaken for tuberculosis?
Yes. The chronic form has very similar symptoms and imaging results. [1]
Is it a rare disease?
In areas where the fungus is common, exposure is frequent, but severe disease is relatively rare.
Can I get it from bats in my attic?
Yes, if their droppings have contaminated the area and the spores become airborne.
What is a bronchoscopy?
A procedure in which a thin camera is used to look inside the airways and collect samples.
Can it cause anemia?
Yes, if it spreads to the bone marrow.
Is it dangerous for pregnant women?
It can be, especially if it becomes disseminated.
Can I travel if I have it?
Consult your doctor. Travel may be difficult if you have severe respiratory symptoms.
Does it cause permanent scarring?
It can in chronic or severe acute cases.
How can I test my soil?
Soil testing for Histoplasma is difficult and is not typically recommended for homeowners.
Related Reading
Ocular Histoplasmosis: Symptoms, Causes, and Treatments explains how this fungal infection can scar the retina and affect vision.
Blastomycosis: The “Soil Fungus” Infection You Breathe In Without Knowing — Why It Lingers for Weeks and How Treatment Clears It describes a similar fungal lung infection found in parts of North America.
Valley Fever Explained: Symptoms, Causes, Treatment, and Who Is at Risk covers another fungal lung infection picked up from soil.
Tuberculosis (TB): Symptoms, Causes, Testing, Treatment and Prevention explains a lung infection that can look like histoplasmosis on scans.
References
Cleveland Clinic. Histoplasmosis: Causes, Symptoms, Diagnosis & Treatment. Cleveland Clinic. Last updated March 8, 2023. https://my.clevelandclinic.org/health/diseases/24811-histoplasmosis
Centers for Disease Control and Prevention. About Histoplasmosis. CDC. Last reviewed April 24, 2024. https://www.cdc.gov/histoplasmosis/about/index.html
Johnson PC, Wheat LJ, Cloud GA, et al. Safety and efficacy of liposomal amphotericin B compared with conventional amphotericin B for induction therapy of histoplasmosis in patients with AIDS. Annals of Internal Medicine. 2002;137(2):105-109. PMID 12118965. https://doi.org/10.7326/0003-4819-137-2-200207160-00008
Brooks RA, Yan K, Head JR. Assessment of prior infection with histoplasmosis using skin test and serological surveys: a global systematic review. Open Forum Infectious Diseases. 2025;12(8):ofaf437. PMID 40765713. https://doi.org/10.1093/ofid/ofaf437
Pasqualotto AC, Le T, Vieceli T, et al. Histoplasmosis: a missing piece in the global efforts to end HIV deaths. The Lancet HIV. 2026;13(5):e338-e352. PMID 41833293. https://doi.org/10.1016/S2352-3018(26)00006-8
Dao A, Kim HY, Halliday CL, et al. Histoplasmosis: a systematic review to inform the World Health Organization of a fungal priority pathogens list. Medical Mycology. 2024;62(6):myae039. PMID 38935903. https://doi.org/10.1093/mmy/myae039
Mayo Clinic Staff. Histoplasmosis - Symptoms & causes. Mayo Clinic. May 16, 2025. https://www.mayoclinic.org/diseases-conditions/histoplasmosis/symptoms-causes/syc-20373495
Disclaimer
This article is for informational purposes only and does not constitute medical advice. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.
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