Histoplasmosis

What is histoplasmosis?

Histoplasmosis is a type of fungal infection in your lungs. You get it from breathing in the fungus Histoplasma capsulatum (H. capsulatum). The fungus lives in the soil in many parts of the world, including the U.S. It’s most commonly found where there are bird or bat droppings (poop) in the soil.

Types of this histoplasmosis

Types of histoplasmosis include acute pulmonary histoplasmosis, chronic cavitary histoplasmosis and progressive disseminated histoplasmosis. Healthcare providers diagnose the type of histoplasmosis based on how long you’ve had symptoms and whether it’s spread to the rest of your body. You can also have histoplasmosis that primarily causes symptoms in your brain (central nervous system histoplasmosis) or your eyes (ocular histoplasmosis).

Acute pulmonary histoplasmosis

Pulmonary histoplasmosis is the most common type of symptomatic H. capsulatum infection. In about 10% of people who are infected with the fungus, it causes symptoms similar to pneumonia, including fever, cough and shortness of breath. If you’re exposed to lower levels of the fungus, you could have milder (subacute) symptoms that last several months.

Chronic cavitary pulmonary histoplasmosis

Chronic cavitary pulmonary histoplasmosis is a long-lasting form of illness most commonly seen in people who have emphysema or chronic obstructive pulmonary disease (COPD). It can cause milder symptoms than those of acute pulmonary histoplasmosis, plus night sweats and weight loss. Symptoms can go on for months or years. It can look similar to tuberculosis. It causes damage to your lungs that gets progressively worse if left untreated.

Progressive disseminated histoplasmosis

Progressive disseminated histoplasmosis happens when H. capsulatum spreads from your lungs to many other parts of your body. It most often happens in people who have severely weakened immune systems, like those with advanced HIV. It can cause progressive shortness of breath, fatigue, weight loss and skin ulcers.

How common is histoplasmosis?

It’s estimated that about 75% of adults who live in areas where H. capsulatum is common have been infected before, even if they never had symptoms.

What does histoplasmosis do to your body?

The fungus H. capsulatum gets into your lungs when you breathe it in from the soil. There, it enters your white blood cells and changes from a mold into its infectious form as a yeast. In most people, your immune cells destroy it, or wall it off from your body with granulomas, before you ever notice any symptoms. In certain circumstances, it can make you sick:

• If you’re exposed to a lot of H. capsulatum at once, it can overwhelm your immune system and cause mild or severe flu-like symptoms and breathing problems.
• If you have certain lung diseases, like COPD, it can cause ongoing damage to your lungs.
• If you have a compromised immune system, it can use your immune cells to spread to other parts of your body. This can cause life-threatening complications.

What are the symptoms of histoplasmosis?

Symptoms of histoplasmosis can include:

• Fever.
• Cough.
• Sweating.
• Shortness of breath (dyspnea).
• Chest pain.
• Headache.
• Muscle aches.
• Rash or bumps on your lower legs (erythema nodosum).

Chronic cavitary pulmonary histoplasmosis can additionally cause night sweats and weight loss. In up to 90% of people, breathing in H. capsulatum doesn’t cause any symptoms, or their symptoms resolve on their own (self-limiting).

What causes histoplasmosis?

The fungus Histoplasma capsulatum causes histoplasmosis. You get it from breathing in the mold from the soil. It grows best in soil that has bat or bird poop in it. It’s found in most parts of the world, but it’s most common in:

• The Ohio and Mississippi River valleys in the U.S. This includes states in the Midwest and South-Central U.S.
• Central and South America.
• Africa.
• Asia.
• Australia.

Most people breathe in H. capsulatum without getting sick. But some people, especially those who are exposed to a lot of fungi or who have certain health conditions, can get noticeable symptoms.

What are the risk factors for histoplasmosis?

You’re more at risk for histoplasmosis if you have a job or hobbies that can disturb large concentrations of the fungus. This includes:

• Exploring caves (spelunking).
• Farming.
• Keeping chickens or birds.
• Demolition or construction.

You’re more at risk for severe or chronic cases of histoplasmosis if you:

• Have a weakened immune system. HIV and immunosuppressive medications are common causes of a weakened immune system.
• Have COPD or emphysema.
• Are over 55 years old or under 1 year old.

What are the complications of histoplasmosis?

Serious complications of histoplasmosis include:

• Scarring or other lung damage.
• Fibrosing mediastinitis. Fibrosing mediastinitis is scarring of the area between your lungs.
• Acute respiratory distress syndrome (ARDS).
• Central nervous system histoplasmosis. If the fungus spreads to your brain, it can cause brain swelling, headaches, confusion, impaired thinking and symptoms similar to stroke.
• Ocular histoplasmosis. If a Histoplasma infection spreads to your eye, it can cause impaired vision or vision loss.
• Spread to other parts of your body. This includes your liver, spleen, bone marrow and skin.

How is histoplasmosis diagnosed?

A healthcare provider might test your blood, pee (urine), mucus from your lungs (sputum), bone marrow or a sample of affected tissue to diagnose histoplasmosis. They can use these samples to:

• Try to grow (culture) H. capsulatum. This is the best way to diagnose histoplasmosis. But this can take a long time — several weeks — and in severe cases, your provider will want to treat you before results are available.
• Look for H. capsulatum yeast.
• Test for signs of H. capsulatum in your body (antigens or antibodies).

They’ll also use imaging like chest X-rays or CT scans to look for changes or damage caused by H. capsulatum. The specific types of test they use depends on what kind of histoplasmosis they think you have and how severe your symptoms are.

What tests are done to diagnose histoplasmosis?

In addition to imaging (like chest X-rays or CT scans), your provider may collect samples of fluids or tissues to look for signs of H. capsulatum or try to grow it over time. They can collect these fluids using:

• Urine or sputum tests. You’ll pee in a cup (urine test) or cough and spit in a tube (sputum test) to get a sample.
• Blood tests. Your provider will take blood from your arm with a needle to get a sample.
• Biopsy.Your provider will take a sample of tissue with a small incision or a needle. For a bone marrow biopsy, the provider will use a needle to take a sample from the inside of your hip bone.
• Bronchoscopy. Your provider uses a thin, lighted tube to look at the inside of your lungs. They can perform a bronchoalveolar lavage (BAL) during this procedure. A BAL “washes” small parts of your lungs with fluid. A provider collects the fluid and sends it to a lab to be tested.

How is histoplasmosis treated?

Histoplasmosis is treated with antifungal medications if necessary. If you have mild symptoms that haven’t gone on for a long time and you’re not at high risk for serious infection, your provider may not treat you right away.

Is there a cure for histoplasmosis?

Yes, antifungal medications can often cure histoplasmosis in people with a healthy immune system. Your provider may treat you with these medications:

• Itraconazole.
• Amphotericin B (AmB).
• Corticosteroids.

What happens if histoplasmosis is left untreated?

If you have a healthy immune system and no underlying conditions, histoplasmosis could go away on its own. But left untreated, it sometimes can spread to other parts of your body, especially if your immune system isn’t working as it should. It can cause lung damage in people with underlying lung disease.

Can histoplasmosis be prevented?

It’s hard to avoid breathing in H. capsulatum fungus if you live in an area where it’s common. While not entirely preventable, there are some steps you can take to reduce your risk of histoplasmosis:

• Avoid areas where you’ll be exposed to dirt or dust, especially in areas where bats or birds live.
• If your job or hobbies expose you to soil that’s likely to have H. capsulatum, use an N95 respirator mask to help filter the air you breathe.

What can I expect if I have histoplasmosis?

What to expect when you have histoplasmosis depends on how severe it is and any underlying conditions. For people with healthy immune systems and mild symptoms, your healthcare provider may “watch and wait” before treating you. If you have a weakened immune system or are very sick, you can expect to take antifungal medications for at least a year.

How long histoplasmosis lasts

Treatment lasts six to 12 weeks or longer for acute pulmonary histoplasmosis. For chronic or severe cases, you take antifungals for at least a year.

What is the survival rate of histoplasmosis?

Most people with healthy immune systems (96%) survive histoplasmosis with treatment. Some studies suggest that the mortality rate for people with a compromised immune system is between 25% and 37%.

How do I take care of myself?

If you have a weakened immune system, COPD or emphysema, you should take extra precautions to reduce your risk of histoplasmosis. Ask your healthcare provider if there are specific steps you should take to protect yourself if you live in an area where H. capsulatum is common.

When should I see my healthcare provider?

See a healthcare provider if you have flu-like symptoms, cough or shortness of breath that aren’t getting better after a week or are getting progressively worse over time. Tell your provider if your job or hobbies might expose you to the fungus that causes histoplasmosis or if you’ve traveled to an area where the fungus is found.

When should I go to ER?

If you have symptoms of any kind of infection and you have a weakened immune system, talk to your provider right away or seek emergency care. Go to the nearest emergency room if you have symptoms of serious illness, including:

• High fever (over 103 degrees Fahrenheit/40 degrees Celsius).
• Severe or sudden shortness of breath.
• Chest pain.
• Coughing up blood.
• Confusion or other mental changes.
• Seizures.
• Blue skin, lips or nails (cyanosis, a sign of low oxygen in your blood).

What questions should I ask my doctor?

It might be helpful to ask a provider:

• Am I at high risk for severe histoplasmosis?
• Are there any special precautions I should take to reduce my risk of histoplasmosis?
• What symptoms should I look out for?
• When should I go to the ER?

A note from Cleveland Clinic

Histoplasmosis is a type of fungal infection in your lungs. Histoplasmosis can be hard to avoid if you live in an area where the fungus grows. Most cases aren’t serious and go away on their own. But if you have lung disease or a weakened immune system, you’re at higher risk for serious complications of histoplasmosis. You and your provider can make a plan together to protect your health and keep an eye out for any symptoms.