What to Know About Valley Fever
Key takeaways:
Valley fever is caused by a fungus that lives in the soil in parts of the U.S. Southwest.
Certain people are more likely to get sick with Valley fever, including anyone over 60 years old or with a weakened immune system.
People who are more likely to get sick from Valley fever should avoid areas where dirt is being disturbed.
If you live in the southwestern part of the U.S., you may have heard of Valley fever. Valley fever is a lung infection caused by the fungus coccidiomycosis. Coccidioidomycosis spores live in soil. Spores are basically the fungus version of seeds — fungi use spores to reproduce and make more fungus. Anytime dirt moves or gets blown away as dust, the spores fly into the air. Once they are airborne we can breathe these tiny spores in through our noses. Spores can then make their way to our lungs and start to grow, which causes a lung infection.
Since no one can avoid dirt and dust all the time, how do you keep from getting Valley fever?
Where can you get Valley fever?
You can only get Valley fever in areas where coccidiomycosis lives in the soil. Coccidiomycosis fungi like hot and dry climates. In the U.S, the fungus is only found in:
Arizona
Nevada
Utah
Southwest New Mexico
West Texas
Valleys of south and central California
Eastern Washington
It also lives in parts of Mexico as well as some countries in Central and South America.
How do you get Valley fever?
You get Valley fever when you breathe in fungi spores. Anytime the dirt is disturbed — like during construction, gardening, or on a windy day — fungi get flung into the air. Once the spores are in the air, you can breathe them in.
The spores then travel from the nose to the lungs. They get caught in sticky mucus inside the lungs where they can start to grow. The immune system is usually able to fight off these spores before they have a chance to start growing. When this happens, you don’t get sick.
But in some cases, the immune system can’t fight off the spores. In these cases, the spores grow inside the lungs and cause infection. From the lungs, the fungus can also travel to other parts of the body and cause infection.
Who is at higher risk of getting Valley fever?
Some people are at higher risk of getting sick with Valley fever because their immune systems can’t fight off the spores. People who are at higher risk include anyone:
Who is over 60 years old
With a weakened immune system
With a history of an organ transplant
With diabetes
With AIDS
Who is pregnant
Who is taking immunosuppressant medications like steroids or chemotherapy
These groups of people are also at risk for developing more serious symptoms from Valley fever if they do get sick.
Is Valley fever contagious?
Valley fever isn’t contagious. People can’t spread the fungus to one another — you have to breathe in the spores to get sick.
What are the symptoms of Valley fever?
About 60% of people who breathe in spores never have any symptoms. That’s because our immune systems fight off the fungus before we can get sick. The remaining people can experience:
Fever
Cough
Fatigue
Muscle soreness
Headache
Chills
Rash
These symptoms usually start between 1 to 3 weeks after being exposed to the spores. Only about 5% to 10% of people get sick enough to have more concerning symptoms like trouble breathing or other lung problems.
In about 1% of people, the fungus spreads to other parts of the body — like the brain, spinal cord, and joints — and causes infection. This usually happens to people who have weakened immune systems.
If you are at higher risk for getting sick with Valley fever, you should see a healthcare provider right away if you have symptoms of Valley fever.
What medications are used to treat Valley fever?
Valley fever is treated with medications called “antifungals.” These are medications that kill fungi, just like antibiotics kill bacteria. The most common antifungals prescribed for Valley fever are:
These medications are taken once or twice a day for 6 to 12 weeks or longer. But not everyone needs antifungal therapy for Valley fever.
Only people who have severe symptoms — or who are at risk for developing severe symptoms — need antifungal treatment. People who have more serious forms of Valley fever, like fungal infections in many parts of the body, need to be treated in the hospital with antifungal medication that is given through an intravenous (IV) line.
For everyone else, there’s no evidence that antifungals prevent complications like lung scarring. There’s also no evidence that antifungal medication makes symptoms go away any faster. If you’re in this group of people, you probably don’t need any treatment. Your symptoms will go away on their own.
How do you lower your risk of developing Valley fever?
It’s important to remember that when you’re traveling to an area with coccidioidomycosis, the risk of getting Valley fever is very low. Unless you’re at higher risk of getting sick with Valley fever, there are no special precautions you need to take. If you want to be extra careful, you can avoid areas that generate a lot of dust — like construction sites.
If you’re at higher risk of getting Valley fever or you live in an area with coccidioidomycosis, there are several things you can do to lower your risk of getting sick:
Avoid areas where dirt is being disturbed — like construction sites and excavation areas. If you can’t avoid these areas, wear an N95 respirator when outdoors.
If there’s a dust storm or it’s very windy, stay inside and close your windows and doors so dust and spores don’t get into your home.
It’s best to stay away from activities like yard work, gardening, or anything that involves digging in the dirt.
Consider adding an air filtration system to your home.
The bottom line
Valley fever is an infection caused by a fungus that lives in the southwestern part of the U.S., especially in California and Arizona. The fungi grow in the soil, but with certain activities like construction work or heavy winds, the fungi move into the air where we can breathe it in and get sick. Certain groups of people are more at risk of getting sick and should see a healthcare provider if they have symptoms of Valley fever. To keep from getting exposed to the fungi, stay away from dust-filled areas like construction sites.
Why trust our experts?
References
Centers for Disease Control and Prevention. (2021). Coccidiomycosis.
Galgiani, J., et al. (2016). Infectious Diseases Society of America (IDSA) clinical practice guideline for the treatment of coccidioidomycosis. Clinical Infectious Diseases.
McCotter, O., et al. (2019). Travel related infectious disease: Coccidiomycosis. CDC Yellow Book.
Muir Bowers, J., et al. (2006). Fatigue in coccidioidomycosis. Quantification and correlation with clinical, immunological, and nutritional factors. Medical Mycology.
