Valley fever, also called coccidioidomycosis (kok-sid-ee-oi-doh-mahy-koh-sis), is an infection caused by breathing in the spores of the fungus Coccidioides. The fungus lives in the soil in the Pacific Northwest and southwestern United States and parts of Mexico, Central and South America. It is common in Arizona and California but can also live in parts of Utah, Nevada, Texas, Washington and New Mexico. People who either live in or travel through these areas are at risk of infection.
Key Facts
- Coccidioidomycosis is not contagious, meaning it cannot be passed from person to person.
- Most people who get coccidioidomycosis have minimal symptoms and do not require treatment.
- Symptoms appear between one to three weeks after exposure and last a few weeks to a few months.
- Five to ten percent of people who get Valley fever will develop serious or long-term lung problems. Approximately one percent will have the disease spread to other parts of the body.
- Currently, there is no vaccine to prevent Valley fever.
How Coccidioidomycosis Affects Your Body
Fungi that cause Valley fever live in the soil. When the soil is disturbed through farming, construction, wind or another activity, the fungal spores become airborne. People in the area may breathe in the fungal spores without knowing they have been exposed. Once inhaled, the fungus multiplies and spreads, leading some people to get sick. People who get sick usually develop symptoms 1-3 weeks after exposure. Because the fungus is inhaled, the disease typically affects the lungs. This can lead to fungal pneumonia. In a small number of people, it may spread outside of the lung and affect other parts of the body. This serious complication is called “disseminated coccidioidomycosis.” Another serious complication that could occur is the fungal infection may progress to coccidioidal meningitis.
Who Is at Risk for Coccidioidomycosis?
Not everyone who is infected by Valley fever will have symptoms. If you are concerned you may be at risk, you should talk to your healthcare provider.
You have an increased risk if you:
- Live in or travel to regions where the Coccidioides fungus lives.
- Are exposed to areas where contaminated soil is being disturbed, such as construction sites or farms
- Have a compromised immune system
A compromised immune system also puts you at increased risk of developing severe or disseminated disease. Your immune system may be compromised due to HIV infection, immune-suppressing medication therapy for autoimmune or rheumatologic diseases, organ transplant, diabetes, or pregnancy.
Reviewed and approved by the American Lung Association Scientific and Medical Editorial Review Panel.
Page last updated: January 7, 2026
