What you need to know about valley fever, a common lung infection in California

This year is shaping up to be a bad one, possibly the worst yet, for valley fever, a fungal disease that causes coughing and fever: California has reported more than 5,300 cases through June, 63% more than the same period last year.

Valley fever is caused by inhaling microscopic particles of a fungus that lives in soil. The fungus usually infects the lungs. In many cases, symptoms are mild and resolve on their own, and the infection is not contagious, but it can become severe and require hospitalization. Approximately 80 people die from valley fever each year in California. In mild cases, symptoms can last for months and require antifungal medication.

The California Department of Public Health said earlier this week that at least several people who traveled to Kern County to attend an outdoor music festival at Lake Buena Vista in May have fallen ill with valley fever. Three attendees were hospitalized, the department said. Health officials are urging people who attended the Lightning in a Bottle festival to contact their health care provider if they feel sick and don't get better.

Historically, the majority of valley fever cases have been reported in Kern County, but a significant number of cases have also been identified in Los Angeles, Fresno and Central Coast counties.

As cases rise across the state, here are four things to know about valley fever.

Valley fever bacteria can travel long distances

Valley fever is caused by a fungus called Coccidioides. Fungal spores can be dispersed into the air from soil by activities such as farming and construction, but can also be carried by the wind. In rare cases, the infection can spread from the lungs to other parts of the body, including the heart and brain.

Valley fever is most common in the dry, hot southwestern United States and northern Mexico. In California, the majority of cases are concentrated in the San Joaquin Valley — in fact, the area for which valley fever is named — but cases have been reported throughout the state.

The bacteria can travel great distances through the air, “so even if you don't live in this area, you can still get it,” says Katrina Heuer, an immunologist and professor at the University of California, Merced.

Kimberly Hernandez, epidemiologist and health services division director for the Kern County Public Health Department, said the best prevention is to avoid dust, which means staying outside as much as possible, especially on windy days. If people must go outside on dusty days, it's a good idea to wear an N95 mask.

Valley fever cases in California have tripled in the past decade

Just over 2,300 people were diagnosed with Valley fever in 2014, according to state data. By 2023, the number of annual cases will more than triple to more than 9,000. And just in the first six months of this year, 5,370 people have been reported with Valley fever. Nearly one-third of the cases this year have been in Kern County.

Experts say the increase in reported infections could be due to several factors.

“As the region grows, there's more and more construction happening in the San Joaquin Valley — more roads, more solar panels, more homes, all of which is disturbing the soil,” Heuer said.

Also, more health care workers and patients are becoming aware of the disease and getting tested.

“We're hopeful that because we've had a lot of Valley fever cases in Kern County in the past, our health care workers are going to be very good at detecting the disease,” Hernandez said, “Even though we have a high number of cases, this is a silver lining because we want people with Valley fever to get diagnosed, if they need medication, we want them to take that medication and be monitored by health care workers.”

Symptoms may be similar to COVID-19

Some people may not experience symptoms, but those who do may experience coughing, fever, chest pain, headache, fatigue, and may develop a rash or night sweats.

Valley fever symptoms usually appear one to three weeks after infection and can last for a month or more.

Because it shares many symptoms with COVID-19, health officials recommend getting tested for COVID-19 first. If COVID is ruled out, a blood test can be done to check for antibodies to the fungus that causes Valley fever. Unlike COVID-19, Valley fever is not contagious.

In Kern County, the disease has become a familiar issue for public officials, and last week the county's public health director, Brynn Carrigan, spoke about her own struggle with valley fever. The Bakersfield Californian reported. In Carrigan's case, the condition developed into meningitis, which causes swelling of the tissues around the spinal cord and brain and can be fatal if left untreated.

“I knew I was sick, but I was shocked to hear how sick I actually was,” Carrigan told the paper.

Climate change is having an impact

Studies have shown that valley fever cases tend to increase during the dry periods following the rainy season. “This is called the grow-and-die hypothesis,” Hernandez says. “The fungus loves moisture, and it grows when it's dark and moist.”

“Then when the next summer comes and it dries out, there's even more valley fever bacteria spreading through the air.”

Hernandez said Coccidioides is a hardy fungus that can survive severe drought.

In some studies, The rise in cases has been attributed to more frequent dust storms in the Southwest. As the planet warms, the region is getting drier, meaning there will be more dust storms that blow fungal spores into the air.

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