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(San Joaquin Fever; Valley Fever)


Sanjay G. Revankar

, MD, Wayne State University School of Medicine

Reviewed/Revised Apr 2021 | Modified Sep 2022
Topic Resources

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

  • 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. They also can be found in Utah, Nevada, and southcentral Washington. 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, 14,364 cases of coccidioidomycosis were reported in 2017.

Coccidioidomycosis is acquired by inhaling spores. Spores are present in soil and can become airborne when the soil is disturbed and travel downwind. 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 from the lungs throughout the body and is often fatal.

Risk factors for progressive coccidioidomycosis

Progressive coccidioidomycosis is uncommon in otherwise healthy people. It is more likely to occur when people

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. Occasionally, when lung infection is severe, spaces may form in the lungs and people may cough up 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, usually only in people with a weakened immune system. It may cause increased shortness of breath and sometimes blood in the sputum.

Coccidioidomycosis may also spread from the lungs to the skin, bones (causing osteomyelitis Osteomyelitis Osteomyelitis is a bone infection usually caused by bacteria, mycobacteria, or fungi. Bacteria, mycobacteria, or fungi can infect bones by spreading through the bloodstream or, more often, by... read more ), joints, liver, spleen, kidneys, and other tissues. If infection spreads to the skin, people may have one sore or many. Joints may become swollen and painful. Deep infections sometimes break through the skin, causing an opening that infected material drains through.

Coccidioides can also infect the brain and the tissues covering the brain (meninges), causing meningitis Subacute and Chronic Meningitis Subacute meningitis is inflammation of the layers of tissue that cover the brain and spinal cord (meninges) and of the fluid-filled space between the meninges (subarachnoid space) when it develops... read more . 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 Overview of the Immune System (proteins released by the fungus) in urine may also be useful.

To identify the fungus and thus confirm the diagnosis, doctors may examine samples of blood, sputum, pus, cerebrospinal fluid, 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. A test to identify the fungus' genetic material (its DNA) can be done on samples taken from the throat and lungs, but this test is not widely available.

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 by vein (intravenously), or posaconazole, given by mouth. For severe cases, amphotericin B is given intravenously.

If meningitis develops, fluconazole is given. People who have had meningitis due to coccidioidomycosis must take fluconazole for the rest of their life.

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 must take drugs for years, often for life.

If bone is infected or if the infection results in spaces in the lung, surgery may be necessary.

Drugs Mentioned In This Article

Generic Name Select Brand Names
Amphocin, Fungizone
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