Valley fever (also called coccidioidomycosis or “cocci”) is a disease caused by the Coccidioides fungus that grows in the soil and dirt in some areas of California and the southwestern United States.
This fungus can infect the lungs and cause respiratory symptoms, including cough, difficulty breathing, fever, and tiredness or fatigue. In rare cases, the Valley fever fungus can spread to other parts of the body and cause severe disease.
You can get Valley fever by breathing in dust from outdoor air that contains spores of the Coccidioides fungus that grows in the soil. Like seeds from a plant, a fungus grows and spreads from tiny spores that are too small to see.
When soil or dirt is stirred up by strong winds or while digging, dust containing these fungus spores can get into the air. Anyone who lives, works, or travels in an area where the Valley fever fungus grows can breathe in these fungus spores from outdoor dust without knowing it and become infected.
Valley fever is not contagious, meaning it cannot spread from one person or animal to another.
Most cases of Valley fever in California are reported from the Central Valley and Central Coast regions of the state. But the number of cases has also been increasing nearby in the northern Central Valley and southern coastal areas of California. People are more likely to get Valley fever if they live, work, or travel in these areas or travel to other places where Valley fever has been reported, including nearby southwestern states, Mexico, and Central and South America.
There is no commercial test available to see if the Valley fever fungus is in the dirt or dust in certain areas, but we do know that Valley fever has been diagnosed in people living throughout California. The map below shows the rates (or number of cases per 100,000 people) of reported Valley fever cases by county in California from 2014 to 2018.
The California Southern San Joaquin (Central) Valley region had the highest rates of Valley fever. Counties in this region include:
- Fresno
- Kern
- Kings
- Madera
- Tulare
The California Central Coast and Northern San Joaquin (Central) Valley regions had increasing rates of Valley fever. Counties in these regions include:
- Merced
- Monterey
- San Benito
- San Joaquin
- San Luis Obispo
- Santa Barbara
- Stanislaus
- Ventura