California is grappling with an unprecedented surge in Valley fever cases, a fungal infection historically confined to the Southwest. The disease, also known as coccidioidomycosis, is increasingly diagnosed outside its usual territory, raising alarms among public health officials and medical professionals.

Brynn Carrigan, 41, of Bakersfield, California, experienced the debilitating effects of Valley fever firsthand. In April 2024,she developed severe headaches that quickly worsened. I went from training for a marathon, raising two teenagers and having a job to essentially being bedridden, Carrigan, who works for Kern County Public Health, said.

Rising Case Numbers

• From 2000 through 2016, California saw 1,500 to 5,500 cases annually.
• Between 2017 and 2023,those numbers jumped to 7,700 to 9,000 cases per year.
• Preliminary data for 2024 indicates more than 12,600 cases, the highest the state has ever recorded, surpassing the previous record in 2023 by about 3,000 cases.
• Early data suggests California is on track for another record-breaking year, with over 3,000 confirmed cases statewide, nearly double the cases reported at the same time in 2023.

Dr. Royce Johnson, chief of the division of infectious disease and director of the Valley Fever Institute at Kern Medical in California, noted the dramatic increase: There is no question that the number of cases of coccidioidomycosis is enormously higher than before. He added, If you want to see me, right now you’d have to wait until July, and that goes for my colleagues, too.

Drought Cycles and Spread

While Kern County has been a hotspot for the fungal infection for the last three years, Gail Sondermeyer Cooksey, an epidemiologist at the California Department of Public Health, explained that new hotspots are emerging along the edges of the Central Valley, specifically in Monterey and San Luis Obispo counties along California’s central coast. Cases in Contra Costa County,just east of Berkeley,have tripled compared with the same time in 2023.

It appears to be spreading out, Sondermeyer Cooksey said.

A 2022 study in The Lancet Planetary Health found that drought years suppress Valley fever cases, but multiple years of drought followed by a wet winter cause cases to rebound sharply. This weather pattern, driven by climate change, influences where new Valley fever hotspots emerge. Longer, drier summers can also shift the transmission season from late summer and early winter to earlier in the year.

Jennifer Head, an assistant professor of epidemiology at the University of Michigan, who studies Valley fever and climate change, stated, We’re seeing wetter wets and drier dries across the Southwest, but California is seeing that to a higher degree.

In Arizona, new hotspots are appearing in regions with climates similar to California’s. The highest increases in Arizona are in the northern plateau regions, which, similar to California, have historically been colder and wetter, Head said.

Wildfires and Valley Fever

The climate patterns expanding Valley fever’s range in california also drive increasingly intense wildfires. Scientists are investigating how fires may worsen valley fever risk, with some research indicating a link between wildfire smoke and higher rates of diagnoses. The state health department warned first responders to January’s fires in Los Angeles County about the increased risk.

Sondermeyer Cooksey noted, it’s not entirely clear whether there is a link between wildfires and Valley fever, but what is important to know is that coccidioides live in the dirt and anything that disturbs the dirt can exacerbate valley fever. Fires do that, then we have all of the reconstruction projects that also disturb soil.

State and local public health departments are closely monitoring areas affected by January’s fires, as reconstruction efforts disturb the soil during peak Valley fever season.

lightning in a Bottle Festival

Diagnosing Valley fever is challenging as its symptoms overlap with other respiratory illnesses. It is important to inform doctors of potential exposure to disturbed soil or dust in areas known to have Valley fever.

Last year,at least 19 people who attended the Lightning in a Bottle music festival were diagnosed with Valley fever,with at least eight hospitalized. Dr. George Thompson, director of the Center for Valley Fever at the University of California, Davis, explained, Lightning in a Bottle is right in the middle of the endemic region, that’s one of the hot spots for the disease.

Thompson added that while most attendees will not get infected, those from non-endemic areas might potentially be at higher risk.

Treatment and Recovery

Thompson said that he and his colleagues are treating more patients for the infection. While only about 1% of cases result in life-threatening complications, once infected, a person never clears the fungus from their body.

Dr. Johnson explained, There is no drug that kills cocci, so what keeps you from being ill is your immune response. Antifungals are used to treat the infection, allowing the immune system to control it. If you then do something to disrupt that immunity, it can start growing again, and that can surface years later, Johnson said.

Carrigan underwent an intense regimen of anti-fungal treatments for a year and has as recovered, even running a marathon. She continues to take anti-fungal medication and emphasizes the importance of recognizing the warning signs of Valley fever and informing doctors of potential exposure.

Even if it’s only 1% of cases, as we see cases increase, the number of people who experience complications is going to rise, too, she said.