What are the risk factors of histoplasmosis?

Acute pulmonary histoplasmosis is associated with a good outcome.

Chronic progressive disseminated histoplasmosis has a long-term protracted course, lasting up to years, with long asymptomatic periods. [16]

If untreated, subacute progressive disseminated histoplasmosis results in death within 2-24 months.

A relapse rate of 50% is associated with acute progressive disseminated histoplasmosis, if treated. The rate decreases to 10-20% with life-long antifungal maintenance. Death is imminent without treatment. [15]

Cure rates in histoplasmal meningitis with therapy are 50%, with a high rate of relapse.

In histoplasmal endocarditis, medical therapy alone rarely is curative.

Morbidity and mortality are related to the duration and extent of systemic infection.

Approximately 90% of patients with acute pulmonary histoplasmosis are asymptomatic. Acute pericarditis can occur in as many as 5% of patients who are symptomatic. [2] The pericardial fluid is generally exudative. [12] Pleural effusions develop in 40-60% of patients with pericarditis.

Chronic pulmonary histoplasmosis occurs in patients with underlying lung disease. Patients develop cavities that may enlarge and result in necrosis. Untreated histoplasmosis may lead to progressive pulmonary fibrosis that results in respiratory and cardiac failure and recurrent infections.

Progressive disseminated histoplasmosis occurs in 1 case per 2000 cases in adults who are immunocompetent. Progressive disseminated histoplasmosis occurs in 4-27% of infected children, older individuals, persons who are immunosuppressed. In the subacute form, death occurs within 2-24 months in untreated cases. The acute form, if untreated, results in death within weeks. [11]

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What Is Histoplasmosis?

Histoplasmosis is a type of lung infection. It is caused by inhaling Histoplasma capsulatum fungal spores. These 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. The disease may progress and spread to other areas of the body. Skin lesions have been reported in 10 to 15 percent of cases of histoplasmosis that has spread throughout the body.

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:

• fever
• dry cough
• chest pain
• joint pain
• red bumps on your lower legs

In severe cases, symptoms may include:

• excessive sweating
• 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

What Causes It?

Fungal spores can be released into the air when contaminated soil or droppings are disturbed. Breathing the spores may lead to an infection.

The spores that cause this condition are commonly found in places where birds and bats have roosted, such as:

• caves
• chicken coops
• parks
• 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 and it’s not contagious.

Types of Histoplasmosis

Acute

Acute, or short-term, histoplasmosis is typically mild. It rarely leads to complications.

The Centers for Disease Control and Prevention (CDC) estimate that between 60 and 90 percent of people who live in areas where the fungus is common have been exposed. Many of these people probably did not have any symptoms of infection.

Chronic

Chronic, or long-term, histoplasmosis occurs far less often than the acute form. In rare cases, it can spread throughout the body. Once histoplasmosis has spread throughout your body it is life-threatening if it isn’t treated.

Widespread disease usually occurs in people with impaired immune systems. In areas where the fungus is common, the CDC says that it may occur in up to 30 percent of people with HIV.

Am I at Risk?

There are two major risk factors for developing this disease. The first is working in a high-risk occupation and the second risk factor is having a compromised immune system.

Occupations

You are more likely to be exposed to histoplasmosis if your job exposes you to disturbed soil or animal droppings. High-risk jobs include:

• construction worker
• farmer
• pest control worker
• demolition worker
• roofer
• landscaper

Weakened Immune Systems

Many people who have been 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

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 respiratory distress syndrome can develop if your lungs fill with fluid. This 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.

Meningitis

Histoplasmosis can cause a serious condition called meningitis. Meningitisoccurs when the membranes surrounding your brain and spinal cord become infected.

Adrenal Glands and Hormone Problems

Infection can damage your adrenal glands and 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 may 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.

Depending on what parts of your body are affected, you may need other tests. 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 purpose 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 instruct to 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 likely be given an oral antifungal medication, but you may also require IV treatment. The most commonly used drugs are:

• ketoconazole
• amphotericin B
• itraconazole

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
• caves
• 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.