Coccidioidomycosis, also known as Valley fever, is an infection caused by breathing in the spores of the fungus Coccidioides found in the soil in the Pacific Northwest and southwestern United States and parts of Mexico, Central and South America.This fungi is more commonly found in Arizona and California but can also be found in parts of Utah, Nevada, Texas, Washington and New Mexico. People who either live in or travel through these areas are at risk for 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.
- Only about five to ten percent of people who get Valley fever will develop serious or long-term lung problems. Less than 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
Once inhaled, the Coccidioides fungus multiplies and spreads, leading to the worsening of the disease. The time from exposure to the development of symptoms may take several weeks. Because the fungus is inhaled, the disease typically affects the lungs. 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 pneumonia.
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 doctor.
You have an increased risk if you:
- Live in or travel to regions where the Coccidioides fungus occurs.
- Are exposed to dust storms or 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, pregnancy.
When to See Your Doctor
Reviewed and approved by the American Lung Association Scientific and Medical Editorial Review Panel.
Page last updated: August 21, 2025
