A fungal infection that is becoming more common in California but was once rarely seen outside of Arizona and northern Mexico appears to have afflicted multiple attendees at the Lightning In a Bottle festival outside Bakersfield in May.

Plenty of Bay Area kids traveled to attend Lightning In a Bottle over Memorial Day weekend this year, and now health officials say they have confirmed five cases of Valley fever linked to the fest. The infection comes from spores that can be kicked up in the dirt of dry valley floors or spread by wind, and can cause cough, fever, fatigue, difficulty breathing, and chest pain.

The California Department of Public Health (CDPH) is now encouraging anyone who experienced such symptoms to seek medical care, saying that they have found five cases but there could likely be more among the 20,000 who attended the three-day festival at Buena Vista Lake.

While the festival happened two months ago, those with underlying conditions could still be feeling symptoms.

"Valley fever is an infectious disease caused by the Coccidioides fungus that grows in the soil and dirt in some areas ​of California," the CDPH says in a release. "alley fever is not contagious, meaning it cannot spread from one person or animal to another. Past outbreaks of Valley fever have been associated with exposure to dust and dirt at outdoor events and jobsites where dirt was being disturbed in areas of California where Valley fever is common."

Officials say that Valley fever has been on the rise, with particularly high numbers of cases reported in 2023 and 2024, across parts of the Central Valley and Central Coast, likely due to two wet winter seasons. There have been 5,400 cases confirmed in the state so far this year.

The CDPH is also trying to alert healthcare providers that they should ask all patients with Valley fever-compatible symptoms where they might have been in the last month or two.

The Chronicle spoke with organizers of Lightning In a Bottle, who said they are working on "preventative measures we can take to reduce Valley fever risk for future festival events."

Festival attendees have been sharing stories on Reddit, with one writing, “About 18 days after I returned home I was hospitalized with a severe lung infection after experiencing a low grade fever, body aches, and a cough. It’s no joke. It’s causing a cavity (a hole) to form inside my right lung and I am not sure when I’ll regain my energy back. I have been sick and fatigued for weeks, even with treatment."

One man who attended the festival said he'd experienced a very severe infection with complications. "This thing has put me through the ringer," he wrote.

"I spent almost 3 weeks in the hospital with valley fever. I ended up having 3 chest tubes to address the fluid surrounding my left lung. I discharged from the hospital July 1. I still have two pockets of fluid on the left lower lobe of my lung as well as the pneumonia infection filling my lung."

Another attendee said, "After reading how many people get sick [at Lightning In a Bottle] it really seems like they should move locations."

The 2025 edition of the festival is already sold out of pre-sale tickets. It is also scheduled to occur at Buena Vista Lake, from May 21 to 25.

Photo via Lightning In a Bottle/Facebook