What Is Histoplasmosis?
Histoplasmosis is a type of lung infection. It is caused by inhaling Histoplasma capsulatum fungal spores. Spores are found in soil and in the droppings of bats and birds. This fungus mainly grows in the central, southeastern, and mid-Atlantic states.
Most cases of histoplasmosis don’t require treatment. However, people with weaker immune systems may experience serious problems.
What Causes It?
Fungal spores can be released into the air when contaminated soil or droppings are disturbed. Breathing the spores may then lead to an infection.
The spores that cause this condition are commonly found in places where birds and bats have roosted, such as:
- chicken coops
- older barns
You can get histoplasmosis more than once. However, the first infection is generally the most severe. The fungus doesn’t spread from one person to another. It’s not contagious.
Types of Histoplasmosis
Acute, or short-term, histoplasmosis is typically mild. It rarely leads to complications.
The Centers for Disease Control and Prevention (CDC) estimate that between 50 and 80 percent of people who live in areas where the fungus is common have been exposed (CDC). Many of them probably did not have any symptoms of infection.
Chronic, or long-term, histoplasmosis occurs far less often than the acute form. In rare cases, it can spread throughout the body. This disseminated form of histoplasmosis is considered life-threatening, unless treated.
Widespread disease mainly occurs in people with impaired immune systems. In areas where the fungus is common, the CDC says it may occur in up to 25 percent of people with HIV (CDC).
Am I At Risk?
There are two major risk factors for developing symptomatic disease. These are working in a high-risk occupation and having a compromised immune system.
You are more likely to be exposed to histoplasmosis if your job exposes you to disturbed soil or animal droppings in areas of the United States likely to have such spores. High-risk jobs include:
- construction worker
- pest control worker
- demolition worker
Weakened Immune Systems
Many people exposed to histoplasmosis do not get noticeably sick. However, your risk of severe infection is higher if you have a compromised immune system. Conditions associated with weakened immunity include:
- being very young or very old
- having HIV or AIDS
- taking strong anti-inflammatory medications like corticosteroids
- undergoing chemotherapy for cancer
- taking TNF inhibitors for conditions such as rheumatoid arthritis
- taking immunosuppressant drugs to prevent a transplant rejection
What Should I Watch For?
Most people who are infected with this fungus have no symptoms. However, the risk of symptoms increases as you breathe in more spores. If you are going to have symptoms, they generally show up about 10 days after exposure.
Possible symptoms include:
- dry cough
- chest pain
- joint pain
- red bumps on your lower legs
In severe cases, symptoms may include:
- sweating a lot
- shortness of breath
- coughing up blood
Widespread histoplasmosis causes inflammation and irritation. Symptoms may include:
- chest pain, caused by swelling around the heart
- high fever
- stiff neck and headaches, from swelling around the brain and spinal cord
Potential Long-Term Complications of Infection
In rare cases, histoplasmosis can be life-threatening. Therefore, it is extremely important to get treatment.
Histoplasmosis can also cause a number of complications.
Acute Respiratory Distress Syndrome
Acute respiratort distress syndrome can develop if your lungs fill with fluid. It can lead to dangerously low levels of oxygen in your blood.
Heart Function Issues
Your heart might not be able to function normally if the area around it becomes inflamed and full of fluid.
Histoplasmosis can cause a serious condition called meningitis. Meningitis occurs when the membranes surrounding your brain and spinal cord become infected.
Adrenal Glands and Hormone Problems
Infection can damage your adrenal glands. This may cause problems with hormone production.
Testing for and Diagnosing Histoplasmosis
If you have a mild case of histoplasmosis, you may never know that you were infected.
Testing for histoplasmosis is usually reserved for people who both have a severe infection and live or work in a high-risk area.
To confirm a diagnosis, your doctor might conduct blood or urine tests. These tests check for antibodies or other proteins that indicate prior contact with histoplasmosis. Your doctor might also take urine, sputum, or blood cultures to make an accurate diagnosis. However, it can take up to six weeks to get results.
You may need other tests, depending on what parts of your body are affected. Your doctor might take a biopsy (tissue sample) of your lung, liver, skin, or bone marrow. You might also need an X-ray or computerized tomography (CT) scan of your chest. The goal of these tests is to determine if additional treatments are needed to address any complications.
Treatments for Histoplasmosis
If you have a mild infection, you probably won’t need treatment. Your doctor might just have you rest and take an over-the-counter medication for symptoms.
If you have trouble breathing or are infected for longer than one month, treatment may be necessary. You will usually be given an oral antifungal medication but may require IV treatment. The most commonly used drugs are:
- amphotericin B
If you have a severe infection, you might need to take your medication intravenously (through a vein). This is how the strongest medications are delivered. Some people may have to take antifungal medication for up to two years.
How Can I Prevent Histoplasmosis?
You can reduce your risk of infection by avoiding high-risk areas. These include:
- construction sites
- renovated buildings
- pigeon or chicken coops
If you can’t avoid high-risk areas, there are steps you can take to help keep spores from getting into the air. For example, spray sites with water before working or digging in them. Wear a respirator mask when there is a high risk of exposure to spores. Your employer is obligated to provide you with appropriate safety equipment if it’s needed to protect your health.