Valley fever outbreak at California music festival shows fungal threat

An outbreak of Valley fever among attendees of an outdoor music festival in California’s Central Valley highlights the growing threat of the fungal infection.

Five cases have been confirmed among people who went to the Lightning in a Bottle festival in Bakersfield in May. Three of them were hospitalized.

“About a week after I got back from the festival, I was hit with severe body aches and crazy fevers,” said Eric Mattson, 33, a musician from San Luis Obispo who said he attended the festival this year. He tested positive for Valley fever last month.

His symptoms progressed to joint pain that made movement difficult, accompanied by night sweats. Mattson said, “I would wake up, like, two to three times a night, drenched in sweat. I would have to change my bedding and pajamas while I was in a lot of pain. It was horrible.

The fungus that causes Valley fever, called coccidioides, thrives in hot, dry climates, so most cases are found in Arizona and California. But climate change is creating more opportunities for it to proliferate, and as a result, cases of Valley fever have been rising in California.

The annual number of infections in the state has increased from less than 1,000 in 2000 to more than 9,000 in 2019. According to a recent report from the California Department of Public Health, there have been 5,370 suspected or confirmed cases so far this year. Department officials did not provide answers to questions about the increase in cases.

In San Joaquin County, the combined number of suspected and confirmed cases has already surpassed 200 this year, compared to last year’s total of 47 and 59 in 2022.

Valley fever does not spread from person to person – instead, the lung infection results from inhaling spores in dust or soil. The name is a reference to the San Joaquin Valley in California, where coccidioides was discovered.

The actual number of cases linked to the music festival may be higher than the state’s count. Mattson said he has not been contacted by the health department, which has not released the names of confirmed cases, so it is unclear whether Mattson is included. NBC News reviewed the medical record showing the positive test result.

Mattson estimated he lost 20 pounds in four to five weeks.

He said he suspected Valley fever, as he had heard reports that some festival-goers had become infected in recent years, but was initially diagnosed with pneumonia. Ultimately, her primary care doctor ordered a blood test, which came back positive early last month.

Situations like Mattson’s are common, said Dr. Geetha Sivasubramanian, assistant clinical professor of medicine at UCSF Fresno: “Often, patients with Valley fever are misdiagnosed as having bacterial pneumonia.”

This is because many doctors are not aware of the disease or test for it too early or mistake it for another respiratory infection, she said. These errors can lead to patients taking antibiotics they do not need instead of appropriate antifungal medications.

About 60% of people with Valley fever have no symptoms, while others develop a cough, fatigue, fever, shortness of breath, night sweats, muscle aches, joint pain, or a rash on their legs or upper body. People who have diabetes or a weakened immune system or who are pregnant are vulnerable to serious lung infections. In very rare cases – about 1% – a lung infection can spread to the bones, joints or brain, which can be deadly.

An ideal setting for the spread of Valley fever

Sivasubramanian said she was not surprised by the accumulation of cases among the more than 20,000 attendees at the music festival.

“We live in an area that is highly endemic for Valley fever, so anyone visiting us who lives in these areas is at risk,” she said.

In the Central Valley, heavy winter rains help the fungus grow in the soil. Then, as temperatures rise and the soil becomes drier, the dust carries the spores into the air.

Activities that raise a lot of dust – such as construction or agriculture – increase the risk of exposure. In 2014, the Centers for Disease Control and Prevention listed five confirmed and five suspected cases of Valley fever for dry, dusty conditions on an outdoor film set.

Lightning in a Bottle seemed to be in the right place at the right time, said Dr. Arturo Casadevall, chair of molecular microbiology and immunology at the Johns Hopkins Bloomberg School of Public Health.

“You need two things: you need a spore cloud and you need people,” he said.

Mattson said wind during the festival kicked up dust near some stages and at the campsite where many attendees stayed.

“When a lot of people are dancing, it definitely raises a lot of dust,” he said.

Valley Fever May Be Expanding to New Areas

As climate change causes more intense rainfall and higher temperatures, it is promoting conditions conducive to the coccidioides fungus. More frequent and intense forest fires can also transport spores to neighboring areas.

Outside of California and Arizona, a 2019 study estimated that Valley fever may already be endemic in certain counties in 10 other states, as far east as Kansas and Oklahoma.

“As deserts expand, we will see cases outside of historic regions,” Casadevall said.

Some researchers also suspect that rodents may help spread the fungus as climate change alters their migration patterns, although others do not think this is common. A 2022 Study detected coccidioides among rodents in Kern County, where the Lightning in a Bottle festival is held.

Mattson said he doesn’t regret attending the festival, but wants others in the area to be aware of the disease and its symptoms.

“You really need to advocate for testing if you’ve been in the valley or a place where there’s a lot of dust in the air,” he said.