Histoplasmosis is an infection that occurs by breathing in spores of the fungus, Histoplasma capsulatum (H. capsulatum). The fungus lives in the soil or in areas contaminated by birds or bars. Most people with histoplasmosis have no symptoms and may never know they are infected. However, histoplasmosis can be serious or even deadly for:

• People with weakened immune systems
• People with chronic diseases
• Infants

About 500,000 people are exposed to H. capsulatum each year in the United States.

Most people with histoplasmosis have no symptoms or have only mild flu-like illnessvery mild ones. Signs and symptoms that happen in rare cases include the following If symptoms do occur, they may include:

• Fever and chills
• Cough and chest pain that get worse when breathing in
• Headache
• Joint pain
• Muscle pain

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:

• Cough, possibly coughing up blood
• Fever and weight loss
• Night sweats
• Shortness of breath

Trouble breathing can happen to people who breathe in very large amounts of the fungus. It is sometimes called "spelunker's lung" because it can happen after exploring caves.

If the disease spreads throughout the body, it affects many organ systems. A person may have the following symptoms:

• Anemia
• Meningitis (inflammation of the membranes of the brain and spinal cord)
• Ulcers in the mouth
• Infection of heart valves
• Pericarditis
• Pneumonia
• Enlarged liver and spleen
• Swollen lymph nodes

Histoplasmosis is caused by a common fungus that is found in mild climates throughout the world. Many people living in the Ohio and Mississippi river valleys of the United States have been infected with the fungus, called H. capsulatum. It grows in moist soil that is rich in nitrogen, or in places contaminated with bird or bat droppings, such as attics, barns, caves, and city parks.

People breathe the spores of fungus into the lungs, where they grow. In people with healthy immune systems, they usually do not spread to other parts of the body. However, in people with weakened immune systems, the disease may spread to other organs.

Histoplasmosis may also occur in the wake of a solid organ transplant, such as a heart, lung, or kidney transplant.

Many people living in mild climates can become infected with histoplasmosis. Those most at risk of becoming infected include:

• Farmers and poultry farmers
• Construction workers
• Spelunkers (cave explorers)
• Geologists and archeologists
• Landscapers and gardeners
• People who have contact with bats

Those at risk of severe infection include:

• People with weakened immune systems (from HIV, corticosteroid therapy, organ transplantation, and chemotherapy)
• Very young children
• Senior adults
• People with chronic diseases, such as lung disease

Because most people with histoplasmosis have no symptoms, it can be hard to diagnose. Doctors sometimes mistake histoplasmosis for tuberculosis because of similar symptoms and imaging test results. In addition to a physical exam, your doctor may do the following tests:

• Fungal culture -- can take several weeks to confirm diagnosis, so this test is not used if someone needs immediate treatment
• Fungal stain or blood test
• Chest x-ray or computerized tomography (CT) scan

It isn’t easy to prevent exposure to the fungus that causes histoplasmosis because it is widespread. However, you can minimize the risk by wearing masks or respirators when in places contaminated by bird or bat droppings.

Mild cases of histoplasmosis may not need to be treated. Doctors treat more serious cases with antifungal medications.

Medications

Medications stop the fungus from growing in the body. Doctors often use these medications in severe cases when the infection has spread to other organs and tissues throughout the body.

• Amphotericin B (Fungizone IV, Abelcet) is given intravenously (IV). Your doctor may start with this drug in severe histoplasmosis and then switch to itraconazole.
• Itraconazole (Sporanox) is taken by mouth for mild to moderate histoplasmosis.

Surgery and Other Procedures

Surgery is only needed in rare cases when serious complications arise.

Nutrition and Dietary Supplements

No supplements cure histoplasmosis and supplements should never be used instead of medical treatment. Ask your doctor about the best ways to add complementary therapies into your overall treatment plan. Always tell your health care provider about the herbs and supplements you are using or considering using.

The following supplements may help reduce symptoms of histoplasmosis or improve the immune system, although there isn't any scientific evidence for their effectiveness:

• Vitamin C. Vitamin C is an antioxidant and may help strengthen the immune system.
• Grapefruit seed extract (Citrus paradisi). Grapefruit seed may have antibacterial, antifungal, and antiviral properties. It may also help strengthen the immune system. There are no studies on grapefruit seed extract in people with histoplasmosis. Grapefruit seed extract interacts with a number of common medications, so don't take it without asking your doctor first.
• Probiotic supplement (containing Lactobacillus acidophilus) may improve immune system function. You should refrigerate your probiotic supplements for best results. People with autoimmune conditions, such as lupus or rheumatoid arthritis, or people with weakened immune systems should ask their doctor before taking probiotics.
• Coenzyme Q10 for antioxidant and immune system support. Coenzyme Q 10 may interact with blood thinners, such as warfarin (Coumadin), clopidogrel (Plavix), or aspirin and make them less effective, so ask your doctor before taking it.

Herbs

Herbs can strengthen and tone the body's systems. As with any therapy, you should work with your provider before starting any treatment.

These herbs have not been studied specifically for histoplasmosis, but in laboratory studies they were shown to stop the growth of some fungus or improve immune system:

• Cat's claw (Uncaria tomentosa) may help reduce inflammation. Cat's claw may boost the immune system, so people with autoimmune diseases (such as rheumatoid arthritis or psoriasis) should avoid it. People on antihypertensive medication should not take cat's claw. People with leukemia should not take cat's claw. Cat's claw may interact with a number of medications, so ask your doctor before taking it.
• Garlic (Allium sativum) may also boost the immune system. Garlic may increase the risk of bleeding. Ask your doctor before taking garlic if you also take blood thinners, such as aspirin, clopidogrel (Plavix), or warfarin (Coumadin).
• Cranberry (Vaccinium macrocarpon). Cranberry contains salicylic acid, the same ingredient in aspirin. People with aspirin sensitivity, and people who take the blood thinners warfarin (Coumadin) or clopidogrel (Plavix) should ask their doctor before taking cranberry.
• Reishi mushroom (Ganoderma lucidum) may strengthen the immune system. Reishi may interact with blood pressure medications and blood-thinning medications.

Warnings and Precautions

The medications used to treat histoplasmosis may interact with a number of other drugs. Be sure to tell your doctor about all the medications you take. Amphotericin can be toxic to the kidneys, so your doctor will watch you carefully while you take it.

Prognosis and Complications

Most people don't have serious complications, but rarely complications may include:

• Fibrous tissue in the lining of the chest wall cavity, which may squeeze the esophagus, heart, or lungs, so they cannot work properly
• Meningitis
• Loss of central vision -- if infection spreads to the eyes

Most cases of histoplasmosis are mild. In the most severe cases, particularly when the infection spreads throughout the body, a person may need to take antifungal medications for a long time. If left untreated, severe cases can cause death. People in areas where the fungus is common may get a second infection, even after treatment.

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