Valley fever, the fungus disease spreading in California, explained

Valley fever , a disease caused by breathing in a type of fungus primarily found in the Southwest, is on the rise in California, according to the state's department of public health.

"People who live in or travel to the Central Valley or Central Coast regions of California may be at increased risk of Valley fever through the fall," the department recently warned .

Compared to more than 9,000 reported cases statewide in 2023, there have already been more 5,000 preliminary cases reported this year as of July 1, the department reported.

Valley fever, also known as coccidioidomycosis or "cocci," is caused by inhaling dust or dirt containing a fungus called Coccidioides. It can infect the lungs and cause respiratory symptoms. In rare cases, it can be fatal.

"Anyone who lives, works, or travels in an area where Valley fever has been reported can become infected, including pets," the health department said in a news release. "Valley fever is not contagious and cannot spread from one person or animal to another."

Where is Valley fever found

In addition to California, Valley fever is typically reported in other western states including Arizona, Nevada, New Mexico and Utah.

Within the past two decades, cases of the illness have increased across the country, according to data from the CDC . Still, thousands of cases are not reported, and many are never diagnosed or are misdiagnosed, the CDC says.

Researchers recently found that drought seasons and climate change play a role in increasing the risk of infection.

During drought periods, peaks in Valley fever cases are less severe, but when rain returns, peaks are particularly high, according to the study published recently in The Lancet Regional Health — Americas journal.

Though timing can differ depending on exact location and year, the study also found that most cases in California occur from September to November.

Valley fever symptoms

Valley fever often starts mild, with signs similar to the flu or COVID-19 , including fever and cough. People may also experience rashes, headaches, fatigue, night sweats, muscle aches or joint pain, according to the CDC.

Symptoms typically develop between 1 and 3 weeks after breathing in spores of the fungus, which occur naturally in the soil of some Western states, primarily across the Southwest.

While some people recover on their own, dangerous complications can develop in as many as 10% of cases , the CDC says.

Certain factors can also increase a person's risk of getting a severe case, including being 60 years of age or older, having diabetes or a condition that weakens the immune system, or being pregnant, according to California's Department of Public Health.

How to treat Valley fever

While potential vaccines have been tested in animals , there is currently none available for treating or preventing Valley fever.

Instead, antifungal treatments , typically fluconazole or amphotericin B, are used to treat some cases of the illness. In other cases, infections resolve without antifungal treatment, the CDC says.

To help prevent Valley fever in areas with high rates, the California health department suggests:

• Staying indoors when it's windy outside and the air is dusty
• Keeping car windows closed and using recirculating air when driving through dusty areas
• Wetting dirt before digging to reduce dust
• Wearing a N95 mask if you must be outdoor in these dusty areas