Valley Fever is ready to slam California again with record-breaking cases: Here's what you need to know

Independent

20-05-2025

California may be facing another record year for Valley fever infections.
The lung infections are caused by a fungus that grows in western soil, resulting in serious or long-term lung problems and potentially death if it is not treated and spreads to the brain. It results in thousands of cases every year in the U.S. and hundreds of deaths.
The Golden State, where Valley Fever was first discovered, is consistently the state with the most infections. After a record year, early state data shows it's on track for what is looking to be another big one. There are already more than 3,100 confirmed cases across the state.
That's more than there were at the same time last year and nearly double the amount in 2023.
'There is no question that the number of cases of coccidioidomycosis is enormously higher than before,' Dr. Royce Johnson, chief of the division of infectious disease and director of the Valley Fever Institute at Kern Medical in California, recently told NBC News. 'If you want to see me, right now you'd have to wait until July, and that goes for my colleagues, too.'
The majority of this year's cases are in Kern, Los Angeles, Monterey and Fresno counties. A significant oil-producing area, wildfire-stricken Kern has often been the epicenter of outbreaks — but there are new areas of concern. Cases in the East Bay's Contra Costa County have more than tripled since 2023. Merced has also seen cases steadily increase and San Bernardino has seen 60 more than last year.
'It appears to be spreading out,' Gail Sondermeyer Cooksey, an epidemiologist at the California Department of Public Health, told the network.
How do exposures occur?
Valley Fever, officially called coccidioidomycosis, was first discovered in Southern California's San Joaquin Valley.
The lung infection is caused by the fungus Coccidioides that grows in soil in western parts of the U.S., with the majority of cases reported in California and Arizona.
Valley Fever is caused by breathing in infectious spores, although some who are exposed are never infected. The spores can be kicked up during wind events, or through agricultural work and construction.
While people can get Valley Fever at any time of the year, they are more likely to be infected during late summer and fall. Cases typically peak between September and November, due to a delay from infection to reporting.
What's the concern?
Symptoms can include fatigue, cough, fever, headache, shortness of breath, night sweats, muscle aches, joint pain and a red rash on the upper body or legs. As many as 10 percent of those who are infected will develop serious or long-term problems in their lungs.
Another 1 percent will see it spread to their skin, bones, joints or brain.
Those older than 60 are more likely to be infected, as well as people who have weakened immune systems, are pregnant, have diabetes and people who are Black or Filipino.
People who work outdoors are also at a higher risk.
The climate connection
Researchers have found that cases of the disease spike in California during a shift from drought to heavy rainfall.
California specifically has seen rapid shifts from extreme drought to long-lasting atmospheric river events in recent years.
Wet winters can provide the ideal conditions for Valley Fever infections, as the summer dries out the land and breaks down the fungus into infectious spores.
After flooding and mudslides in March, the state is in for a hot and dry summer, according to federal forecasters.
'As climate change alters the timing and intensity of precipitation in California, we see longer high-risk periods for Coccidioides exposure,' Simon Camponuri, a PhD candidate at U.C. Berkeley, said in a statement.