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Valley fever is quietly spreading across California. This fungal illness, caused by soil-based spores, often starts like the flu but can become much more serious. Once rare, the disease is now surging, especially in the Central Valley and coastal areas, according to health officials.

As of the end of July, there were 6,761 cases confirmed, which means if this pace continues, the total 2025 numbers will likely exceed the 12,595 cases seen in 2024.

Last year’s total was a new record for the state, where the average has been 7,000 to 9,000 cases annually between 2016 and 2024, as per data from the California Department of Public Health (CDPH).


What is valley fever?

Valley fever, or coccidioidomycosis , is a fungal infection caused by inhaling spores of Coccidioides from soil. The coccidioides fungus causes infection when inhaled. People with suppressed immune systems are particularly at risk.

Most cases of Valley fever in California are reported from the Central Valley and Central Coast regions of the state. In fact, Valley fever gets its name from the Central (San Joaquin) Valley because that's where it is most common in California.

The initial form is often mild, with few symptoms. When symptoms do occur, they may resemble those of the flu, including fever, cough, chills, and chest pain. Mild cases clear up on their own. If symptoms don't improve, antifungal medication may be necessary.



Valley Fever’s rise in California: Why the sudden spike

Over the past few decades, California has seen a dramatic rise in cases of valley fever, from under 1,000 cases in 2000 to over 12,500 in 2024. Provisional data show that in the first six months of 2025 alone, more than 6,000 cases have already been reported, putting the state on track to beat last year’s record high.

This increase isn't random. Experts point to climate change creating a ‘perfect storm’, wet winters fuel fungal growth, followed by dry, windy summers that stir spores into the air. Cases are concentrated in the San Joaquin Valley, but now the Central Coast and even certain Bay Area counties are seeing sharp increases. Monterey County's cases jumped by 260%, and Ventura saw a 92% rise.

The rise in cases is linked to shifting weather patterns that make the fungus thrive. Farmers, construction workers, and even visitors to dusty regions face the highest risk. Moreover, the case count is likely to increase due to delays in reporting.

"Valley fever is a serious illness that’s here to stay in California," said Erica Pan, director of the state public health department, in a statement.


Valley fever symptoms : More than just a cold

Valley fever often looks like a lingering cold or flu. Common symptoms include:

Fever, cough, fatigue, shortness of breath

Muscle or joint aches, headaches, chills, night sweats

Skin rash; red spots often on the legs, chest, or back

Typically, symptoms appear 1 to 3 weeks after inhaling spores. Many people don’t get sick at all, but for those who do, the illness can linger for weeks or months.

In rare but serious cases, the infection spreads beyond the lungs to the brain, bones, skin, or spinal cord, leading to meningitis, bone lesions, or even death. These cases require long-term antifungal treatment, sometimes for life.



Who’s at risk?

Valley fever doesn’t discriminate, but certain people are more vulnerable:

Outdoor workers, such as farm laborers, construction crews, and wildland firefighters exposed to dust and soil disruption.

Elderly adults, pregnant individuals, and those with weakened immune systems (e.g., HIV/AIDS, transplant recipients).

People with diabetes or certain ethnic backgrounds, like Filipino, African American, or Hispanic individuals, face a heightened risk of severe disease.

Even healthy people can become severely ill; doctors have noted worrying increases in disease severity among the general population.


Prevention: What you can do to protect yourself

While there’s no vaccine yet, here are key steps you can take:

Avoid dusty areas, especially during windy or dry periods.

Wear an N95 respirator if you must be in dusty, outdoor conditions.

Stay indoors when dust is heavy, and keep windows and doors closed.

Use air filtration systems indoors for cleaner breathing air.

Wash cuts and skin injuries promptly to prevent skin infection.

See a doctor right away if symptoms like cough or fatigue don’t improve after 7-10 days, especially if you've been in affected regions.