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Coccidioidomycosis -ˌȯid-ō-(ˌ)mī-ˈkō-səs

(San Joaquin Fever; Valley Fever)

By Sanjay G. Revankar, MD, Professor of Medicine and Director, Infectious Disease Fellowship Program, Division of Infectious Diseases, Wayne State University School of Medicine
Jack D. Sobel, MD, Dean and Distinguished Professor of Medicine, Wayne State University School of Medicine

Coccidioidomycosis is infection, usually of the lungs, caused by the fungus Coccidioides immitis.

  • The infection is caused by inhaling spores of the fungus.

  • If mild, the lung infection causes flu-like symptoms and sometimes shortness of breath, but the infection may worsen and spread throughout the body, causing various symptoms.

  • The diagnosis can be confirmed by identifying the fungi in samples of infected materials examined under a microscope or cultured.

  • Antifungal drugs are usually taken for 6 to 12 months but sometimes for life.

The spores of Coccidioides are present in soil in the southwestern United States, the central valley of California, northern Mexico, parts of Central America, and Argentina. About 30 to 60% of people who live in one of these areas are exposed to the fungus at some point during their life. In the United States, about 150,000 people develop this infection each year, but fewer than half have symptoms.

Farmers and others who work with or are exposed to disturbed soil are most likely to inhale the spores and become infected. People who become infected while traveling may not develop symptoms until after they go home.

Coccidioidomycosis occurs in two forms:

  • Mild lung infection (acute primary coccidioidomycosis): The infection disappears without treatment. This form accounts for most cases.

  • Severe, progressive infection (progressive coccidioidomycosis): The infection spreads throughout the body and is often fatal.

Progressive coccidioidomycosis is uncommon. This form is more likely to occur when the immune system is weakened—by disorders (particularly AIDS) or by drugs that suppress the immune system (see Table: Risk Factors for Developing Fungal Infections). It is more common among men and among Filipinos, blacks, and Native Americans.

Symptoms of Coccidioidomycosis

Most people with acute primary coccidioidomycosis have no symptoms. If symptoms develop, they appear 1 to 3 weeks after people are infected. Symptoms are usually mild and often flu-like. They include a cough, fever, chills, chest pain, and sometimes shortness of breath. The cough may produce sputum and occasionally, when lung infection is severe, blood.

The progressive form may develop weeks, months, or even years after the initial infection. Symptoms include mild fever and loss of appetite, weight, and strength. The lung infection may worsen, causing increased shortness of breath. The infection may also spread from the lungs to the bones, joints, liver, spleen, and kidneys. Joints may become swollen and painful. Deep infections sometimes break through the skin, causing an opening that infected material drains through.

The fungi can also infect the brain and the tissues covering the brain (meninges), causing meningitis. This infection is often chronic, causing headaches, confusion, loss of balance, double vision, and other problems. Untreated meningitis is always fatal.

Diagnosis of Coccidioidomycosis

  • Blood tests

  • A chest x-ray

  • Examination, culture, or testing of a sample of blood or other tissue

A doctor may suspect coccidioidomycosis if people develop symptoms after living in or recently traveling through an area where the infection is common.

Blood tests to detect antibodies to the fungus (serologic tests) and a chest x-ray are typically done. In people with a healthy immune system, blood tests can usually detect these antibodies if coccidioidomycosis is present. Chest x-rays usually show characteristic abnormalities. These findings help doctors make the diagnosis.

A test that detects antigens (produced by the fungus) in urine may also be useful.

But to identify the fungus and thus confirm the diagnosis, doctors may examine samples of blood, sputum, pus, or other infected tissue under a microscope or send them to a laboratory to be cultured. Because culturing Coccidioides may take up to 3 weeks, doctors typically rely on the blood tests and chest x-ray.

Treatment of Coccidioidomycosis

  • Antifungal drugs

Acute primary coccidioidomycosis typically goes away without treatment in otherwise healthy people, and recovery is usually complete. However, some doctors prefer to treat such people because of the small chance that the coccidioidomycosis will spread. Also, when people are treated, symptoms resolve more quickly. Treatment is usually with an antifungal drug, such as fluconazole, for 3 to 6 months.

Progressive coccidioidomycosis is usually fatal unless it is treated, particularly if the immune system is weakened. About 70% of people with AIDS die within 1 month after being diagnosed. For mild to moderate progressive coccidioidomycosis, fluconazole or itraconazole is given by mouth. Alternatively, the doctor may treat the infection with voriconazole, given by mouth or intravenously, or posaconazole, given by mouth. For severe cases, amphotericin B is given intravenously.

If meningitis develops, fluconazole is given.

Although drug treatment can be effective in localized infections (for example, in the skin, bones, or joints), relapses often occur after treatment is stopped. Usually, people with a weakened immune system and people who have had meningitis must take drugs for years, often for life.

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