Coccidioidomycosis

Definition

Coccidioidomycosis is an infection caused by inhaling the microscopic spores of the fungus Coccidioides immitis. Spores are the tiny, thick-walled structures that fungi use to reproduce. Coccidioidomycosis exists in three forms. The acute form produces flu-like symptoms. The chronic form can develop as many as 20 years after initial infection and, in the lungs, can produce inflamed, injured areas that can fill with pus (abscesses). Disseminated coccidioidomycosis describes the type of coccidioidomycosis that spreads throughout the body affecting many organ systems and is often fatal.

Description

Coccidioidomycosis is an airborne infection. The fungus that causes the disease is found in the dry desert soil of the southwestern United States, Mexico, and Central and South America. Coccidioidomycosis is sometimes called San Joaquin fever, valley fever, or desert fever because of its prevalence in the farming valleys of California. Although commonly acquired, overt coccidioidomycosis is a rare disease. Chronic infections occur in only 1 out of every 100,000 people.

Although anyone can get coccidioidomycosis, farm laborers, construction workers, and archaeologists who work where it is dusty are at greater risk to become infected. People of any age can get coccidioidomycosis, but the disease most commonly occurs in the 25-55 age group. In its acute form, coccidioidomycosis infects men and women equally.

Chronic and disseminated forms of coccidioidomycosis occur more frequently in men and pregnant women. Although it is not clear why, people of color are 10-20 times more likely to develop the disseminated form of the disease than caucasians. People who have a weakened immune system (immunocompromised), either from diseases such as AIDS or leukemia, or as the result of medications that suppressed the immune system (corticosteroids, chemotherapy), are more likely to develop disseminated coccidioidomycosis.

Causes & symptoms

When the spores of C. immitis are inhaled, they can become lodged in the lungs, divide, and cause localized inflammation. This is known as acute or primary coccidioidomycosis. The disease is not spread from one person to another. Approximately 60% of people who are infected exhibit no symptoms (asymptomatic). In the other 40%, symptoms appear 10-30 days after exposure. These symptoms include a fever which can reach 104°F (39.5°C), dry cough, chest pains, joint and muscle aches, headache, and weight loss. About two weeks after the start of the fever, some people develop a painful red rash or lumps on the lower legs. Symptoms usually disappear without treatment in about one month. People who have been infected gain partial immunity to reinfection.

The chronic form of coccidioidomycosis normally occurs after a long latent period of 20 or more years during which the patient experiences no symptoms of the disease. In the chronic phase, coccidioidomycosis causes lung abscesses that rupture, spilling pus and fluid into the lungs, and causing serious damage to the lungs. The patient experiences difficulty breathing and has a fever, chest pain, and other signs of pneumonia. Medical treatment is essential for recovery.

In its disseminated form, coccidioidomycosis spreads to other parts of the body including the liver, bones, skin, brain, heart, and lining around the heart (pericardium). Symptoms include fever, joint pain, loss of appetite, weight loss, night sweats, skin lesions, and difficulty breathing. Also, in 30-50% of patients with disseminated coccidioidomycosis, the tissue coverings of the brain and spinal cord become inflamed (meningitis).

Diagnosis

Many cases of coccidioidomycosis go undiagnosed because the symptoms resemble those of common viral diseases. However, a skin test similar to that for tuberculosis will determine whether a person has been infected. The test is simple and accurate, but it does not indicate whether the disease was limited to its acute form or if it has progressed to its chronic form.

Diagnosis of chronic or disseminated coccidioidomycosis is made by culturing a sample of sputum or other body fluids in the laboratory to isolate the fungus. A blood serum test is used to detect the presence of an antibody produced in response to C. immitis infection. Chest x rays are often used to assess lung damage, but alone cannot lead to a definitive diagnosis of coccidioidomycosis because other diseases can produce similar results on the x ray.

Treatment

In most cases of acute coccidioidomycosis, the body's own immune system is adequate to bring about recovery without medical intervention. Fever and pain can be treated with non-prescription drugs.

Chronic and disseminated coccidioidomycosis, however, are serious diseases that require treatment with prescription drugs. Patients with intact immune systems who develop chronic coccidiodomycosis are treated with the drug ketoconazole (Nizoral) or amphotericin B (Fungizone). Patients with suppressed immune systems are treated with amphotericin B (Fungizone). Amphotericin B is a powerful fungistatic drug with potentially toxic side effects. As a result, hospitalization is required in order to monitor patients. The patient may also receive other drugs to minimize the side effects of the amphotericin B.

Patients with AIDS must continue to take itraconazole (Sporonox) or fluconazole (Diflucan) orally or receive weekly intravenous doses of amphotericin B for the rest of their lives in order to prevent a relapse. Because of the high cost of fluconazole, Pfizer, the manufacturer of the drug, has established a financial assistance plan to make the drug available at lower cost to those who meet certain criteria. Patients needing this drug should ask their doctors about this program.

Alternative treatment

Alternative treatment for fungal infections focuses on creating an internal environment where the fungus cannot survive. This is accomplished by eating a diet low in dairy products, sugars, including honey and fruit juice, and foods like beer that contain yeast. This is complemented by a diet consisting, in large part, of uncooked and unprocessed foods. Supplements of vitamins C, E, A-plus, and B complex may also be useful. Lactobacillus acidophilus and Bifidobacterium will replenish the good bacteria in the intestines. Antifungal herbs, like garlic (Allium sativum), can be consumed in relatively large does and for an extended period of time in order to increase effectiveness.

Prognosis

Most people who are infected with coccidiodomycosis only suffer from the mild, acute form of the disease and recover without further complications. Patients who suffer from chronic coccidiodomycosis and who have no underlying lung or immune system diseases also stand a good change of recovery, although they must be alert to a relapse.

The picture for patients with the disseminated form of the disease, many of whom have AIDS, is less positive. Untreated disseminated coccidiodomycosis is almost always fatal within a short time. With treatment, chance of survival increases, but the death rate remains high when meningitis or diffuse lung (pulmonary) disease is present. AIDS patients must constantly guard against relapse.

Prevention

Because the fungus that causes coccidioidomycosis is airborne and microscopic, the only method of prevention is to avoid visiting areas where it is found in the soil. Unfortunately, for many people this is impractical. Maintaining general good health and avoiding HIV infection will limit coccidioidomycosis to the acute and relatively mild form in most people.

Key Terms

Abscess

An area of inflamed and injured body tissue that fills with pus.

Acidophilus

The bacteria that usually found in yogurt.

Antibody

A specific protein produced by the immune system in response to a specific foreign protein or particle called an antigen.

Antigen

A foreign protein to which the body reacts by making antibodies.

Asymptomatic

Persons who carry a disease but who do not exhibit symptoms of the disease are said to be asymptomatic.

Bifidobacteria

A group of bacteria normally present in the intestine. Commercial supplements containing these bacteria are available.

Corticosteroids

A group of hormones produced naturally by the adrenal gland or manufactured synthetically. They are often used to treat inflammation. Examples include cortisone and prednisone.

Immunocompromised

A state in which the immune system is suppressed or not functioning properly.

Meningitis

An inflammation of the membranes surrounding the brain or spinal cord.

Pericardium

The tissue sac around the heart.

Further Reading

For Your Information

Organizations

• American Lung Association. 800-LUNG-USA. http://www.lungusa.org.
• Centers for Disease Control and Prevention. 1600 Clifton Road NE, Atlanta, Georgia 30333. 404-639-3534. http://www.cdc.gov.
• National Aids Clearinghouse. 800-458-5231.
• National Aids Hotline. 800-342-AIDS.
• Project Inform. 205 13th Street #2001, San Francisco, CA 94103. 800-822-7422 or 415-558-9051. www.projinf.org.

  Other

• Powderly, William G. "Coccidioidomycosis." Journal of the International Association of Physicians in AIDS Care. (December 1996) http://www.iapac.org/diseases/fungi/cocc.html.

Gale Encyclopedia of Medicine. Gale Research, 1999.