Valley Fever or San Joaquin Fever (Coccidiodomycosis)


Valley fever is an airborne fungal infection. It starts in the lungs, and if not treated, it spreads to the bones and destroys them.


In many people, valley fever causes mild, flu-like symptoms or none at all. Valley fever, therefore, often goes undiagnosed and goes away without treatment.

Symptoms include:

  • Blood in the sputum
  • Chest pain
  • Chills
  • Cough
  • Fever
  • Sore throat
  • Sputum production

In some people, however the infection may become severe and lead to a pneumonia-like illness. The disease may also affect other parts of the body, such as the skin, joints and brain. Valley fever can be fatal in people with weakened immune systems. The severe form of valley fever may develop a few weeks, months or sometimes years after the primary infection, and it may develop even after leaving the area where the fungi live.

Symptoms of this form include:

  • Low-grade fever
  • Anorexia
  • Weight loss
  • Weakness

The heavy involvement of the lungs may cause difficulty breathing or the skin to turn bluish from lack of oxygen. If it spreads beyond the lungs, it usually involves one or more tissue sites in the bones, joints, skin, organs or brain. Sites away from the lungs often become chronic and recur, sometimes long after antifungal therapy has been completed, seemingly successfully.

Causes and Risk Factors

Valley fever is caused by the fungus coccidioides immitis, which grows in arid soil through the southwestern United States, Mexico, Central America and South America. It was first identified in California's San Joaquin Valley. Infection occurs when the spores of the fungus are inhaled.

Progressive valley fever is more common in men than women. People who are at a greater risk of contracting valley fever are those who:

  • Have HIV infection
  • Are on therapy that suppresses their immune systems
  • Are in the second half of pregnancy
  • Have just given birth
  • Are elderly


Tests that a doctor may order to confirm a diagnosis of valley fever include:

  • A chest X-ray that shows thin-walled cavities in the lung
  • Blood tests that show antibodies produced by the body to fight the fungus
  • Examining sputum, lung fluid, spinal fluid or fluid that has drained from skin lesions under a microscope and finding evidence of the fungus
  • Growing cultures from infected body fluids or tissue samples


Without treatment, valley fever that has spread beyond the lungs is usually fatal. In low-risk patients, the form that is limited to the lungs usually does not require treatment.

Treatment may include:

  • Antifungal drugs, such as fluconazole or amphotericin B
  • Surgery to remove involved bone if osteomyelitis occurs

People can acquire Valley Fever more than one time.

© 2000-2022 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.
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