California is seeing a disturbing increase in Valley Fever infections, with 6,761 cases reported as of the end of July 2025. If the trend persists, the state is likely to break the all-time record of 12,595 infections set in 2024, and health officials and researchers are sounding the alarm about the role of climate change in the spread of this fungal infection.
Understanding Valley Fever
Valley Fever, also referred to as coccidioidomycosis or “cocci,” is an illness caused by a fungus that exists in soil throughout California and other Southwestern states. The disease is transmitted when spores are stirred up into the air and are breathed into the lungs, infecting humans and animals alike. There is fever, cough, chest discomfort, and exhaustion, often mimicking other respiratory diseases such as pneumonia or even COVID-19. This often results in misdiagnosis or a delay in appropriate treatment.
Who is at Risk?
Although some individuals can breathe in the spores without getting sick, others are at higher risk of contracting serious infections. High-risk populations are individuals above 60 years of age, pregnant women, those with compromised immune systems, diabetics, and individuals who have regular exposure to dust, e.g., construction workers. The Centers for Disease Control and Prevention (CDC) states that roughly 1 percent of infections will spread from the lungs into organs in the body like skin, bones, joints, or brain. Also, 5 to 10 percent of the patients will have serious or chronic lung complications.
Most people recover from Valley Fever within weeks or months without needing medical attention. Severe infections can require hospitalization and antifungal drugs to treat the infection. Early detection is important to prevent complications and allow patients to receive proper care.
Increasing Cases Tied to Climate Change
Valley Fever has risen steadily in the United States since the year 2000. Where the few hundred annual cases reported around the start of the century were falling short of 1,000, it rose to over 9,000 by the year 2019. Specialists have attributed the rise to prolonged droughts, increased temperatures, and soil disturbance, all tending to provide healthy conditions for the fungus to germinate and proliferate.
As California prepares for a record-breaking year, or so it is hoped, public health authorities are reminding residents, especially those at greatest risk, to take protective measures, such as avoiding dust and getting immediate medical attention if they experience breathing difficulty.
