Valley fever (coccidioidomycosis) is an infection caused by the fungus Coccidioides. Coccidioides grows in the soil in the southwestern U.S., parts of Washington state and Central and South America. Most of the time, Valley fever doesn’t cause symptoms or symptoms go away on their own. Rarely, you can have ongoing lung issues or serious illness.
Valley fever, also called coccidioidomycosis (“cahk-sid-ee-oy-doh-my-KOH-sis”), is an infection caused by breathing in the fungus Coccidioides (“cahk-sid-ee-OY-deze”). Coccidioides lives in the soil in the southwest U.S., parts of Washington state, and Central and South America. It’s named for the San Joaquin Valley in California, where it was first discovered.
Valley fever is the earliest stage of a Coccidioides infection. Valley fever often has no symptoms or flu-like symptoms, but it can sometimes progress to more serious stages of coccidioidomycosis.
Anyone who breathes in the fungus can get infected, but Valley fever is most common in adults over age 60.
Certain people are also at higher risk:
About 20,000 people are diagnosed with Valley fever each year. It’s most common in California and Arizona.
The Coccidioides fungus breaks apart into microscopic reproductive parts (spores) that travel through the air you breathe. They settle into the airways in your lungs where they grow into larger clusters of more spores (spherules).
The spherules can break apart and send more spores out into other parts of your lungs and sometimes other parts of your body. Those spores can grow into spherules of more spores and keep spreading the fungus in your body.
In many cases, Valley fever doesn’t cause any symptoms. If you do have symptoms of Valley fever, they might include:
When seen together, fever, nodules under the skin and joint stiffness are sometimes called desert rheumatism.
Symptoms of Valley fever usually go away on their own after a few weeks or months.
A small number of people can have ongoing disease in their lungs. If it goes on for a long time, it’s usually called chronic pulmonary coccidioidomycosis instead of Valley fever. This may be symptomless or cause symptoms like:
There are two forms of Coccidioides fungi that cause Valley fever: Coccidioides immitis (C. immitis) grows in the soil in California and Coccidioides posadasii (C. posadasii) grows in other parts of the U.S. and Central and South America. They both cause the same symptoms.
Disturbing the soil — particularly during construction or dust storms — breaks apart the fungus, which releases its reproductive parts (spores) into the air. You inhale the spores and they settle in your lungs where they can grow and spread more spores. The spores themselves and your immune system’s response to them cause symptoms.
Complications of Valley fever are uncommon, with only about 1% of those who are symptomatic going on to develop severe cases. Serious complications include:
One of the most serious complications of Valley fever is when the fungus spreads outside of your lungs. It can spread to your skin, bones, joints, liver, pancreas, kidneys and brain. When coccidioidomycosis spreads to your brain, you can develop coccidioidal meningitis, a life-threatening condition. Symptoms of coccidioidal meningitis include:
No, Valley fever isn’t contagious from person to person like the flu. In extremely rare cases, you might be able to inhale spores from an open wound on someone who has Valley fever but this is unlikely. Most of the time, the only way to get it is to inhale spores from the air outdoors.
To diagnose Valley fever, your healthcare provider will perform a physical exam and ask you about your symptoms and travel history. They may order blood tests, imaging (chest X-ray or CT scan) or biopsies.
To diagnose Valley fever, your healthcare provider may order some or all of these tests:
Treatment for Valley fever will depend on how severe your condition is and how your provider wants to manage it. They might recommend keeping an eye on your symptoms before prescribing medications, or they might treat you in order to reduce the risk of serious illness. If you have a serious or ongoing infection or if you have risk factors for severe illness (like chronic pulmonary disease) they may prescribe antifungal medications.
If you need to be treated for Valley fever, your healthcare provider may prescribe one of these medications:
Your healthcare provider may prescribe antifungal treatments for Valley fever for three to six months. Your treatment may last longer depending on your case.
Unfortunately, it’s hard to avoid breathing in Coccidioides fungal spores if you live in an area where they’re common. While not entirely preventable, there are some steps you can take to reduce your risk of Valley fever:
In most cases, people with Valley fever infections recover without any long-term effects. A small number of people develop ongoing lung infections that may take several years to resolve.
In rare cases, the fungus can move to other parts of your body. If left untreated, coccidioidomycosis in your brain can be fatal.
Most people survive getting sick with Valley fever. Less than 1% of people diagnosed with Valley fever die from it.
Usually if you’ve had Valley fever and recovered, you’re immune to it — this means you’re very unlikely to get it again.
If you are over 60, pregnant or living with a compromised immune system, you may want to take extra precautions to reduce your risk of Valley fever. Ask your healthcare provider if there are specific steps you should take to protect yourself if you live in an area where Coccidioides is common.
If you live in an area where Coccidioides is common and you’ve had flu-like symptoms for more than a week, contact your healthcare provider. If don’t live in an area with Coccidioides but have recently traveled to one, make sure you mention that to your provider.
If you’ve been diagnosed with Valley fever, contact your healthcare provider or go to the nearest ER if you experience any of these symptoms:
Unfortunately, the spores of Coccidioides are microscopic and there’s no recommended way to identify or get rid of them from your yard.
A note from Cleveland Clinic
Valley fever can be hard to avoid if you live in areas where the fungus grows. Fortunately, most cases aren’t serious and go away on their own.
If you’re pregnant, over 60 or living with a compromised immune system, you’re at higher risk for serious complications of Valley fever. You and your provider can make a plan together to protect your health and keep an eye out for any symptoms.
Last reviewed by a Cleveland Clinic medical professional on 08/24/2022.
Learn more about our editorial process.