A lung infection named after the San Joaquin Valley is surging in the region, and case counts in San Joaquin County have already surpassed last year’s high during the same span, health reports show.
The number of Valley fever cases in California in 2024 was the highest reported in a year. And there has been a significant increase this year in provisional cases, which include suspected, probable and confirmed infections.
The illness, also known by its official name, coccidioidomycosis — or “cocci” — is caused by fungus that grows in the soil in parts of California and the Southwest. Those who work outdoors, especially in rural areas, are most susceptible to the infection.
In San Joaquin County, there has been a 13.8% increase in the number of Valley fever cases in the first seven months of 2025, state health officials report.
There were 272 provisional cases reported in the county through July 1, according to data from the California Department of Public Health. That’s up from 239 cases during the same period last year.
Most cases of Valley fever in California are reported in the Central Valley and Central Coast. But cases have also been increasing in Southern California. There have been 1,945 cases reported in Kern County and 829 cases in Los Angeles County, state data shows. However, unlike San Joaquin County, both Kern and L.A. counties have seen decreases in case counts this year.
Overall, California has reported 6,761 provisional cases in the past seven months. That’s up from 6,189 cases during the same span last year, the health department reported. Cases in the state have steadily risen over the past two decades, from less than 1,000 cases in 2000 to last year’s record high of nearly 12,500, health department records show.
People can be exposed to the fungus that causes Valley fever yet not get sick. Those who do become infected often do not know they have the illness because symptoms are similar to other respiratory diseases, including COVID-19 and pneumonia.
Valley fever symptoms — including shortness of breath, fatigue, cough, fever and muscle aches or joint pain — can last for a few weeks to a few months. Pets can also be infected, but Valley fever does not spread between people and animals or from person to person.
Many who contract the infection get better on their own without treatment. However, health care providers may prescribe antifungal medications to reduce symptoms or for those with more serious infections, the U.S. Centers for Disease Control and Prevention says.
California health experts say people can reduce their risk of Valley fever exposure by taking precautionary steps to avoid breathing in dust when outdoors. Tips include:
- When it is windy outside and the air is dusty, stay indoors and keep windows and doors closed.
- While driving, keep car windows closed and use recirculating air conditioning, if available.
- If individuals must be outdoors in dusty areas, they should consider wearing a properly fitted N-95 mask.
Employers with outdoor workers should also take steps to limit their exposure to airborne dust, such as watering down soil before digging. And anyone engaging in off-road recreational activities, where airborne dust exposure is common, should wear goggles and mask protection, experts say.