Valley Fever Cases Surge in the US
Data models estimate that the number of coccidioidomycosis (valley fever) cases reported through US surveillance in 2019 was 10 to 18 times higher than previously thought. This led to 18,000 to 28,000 related hospitalizations and 700 to 1,100 deaths. The burden of this fungal lung infection is substantially higher than anticipated, highlighting the need for increased awareness and prevention efforts.
Valley fever, a reportable disease in some states, typically sees 10,000 to 20,000 cases reported annually in the United States, with California and Arizona being the most affected states. However, thousands of cases go unreported or misdiagnosed, indicating a much larger impact than official figures suggest.
Recent reports reveal that 97% of Valley Fever cases in the US are concentrated in Arizona and California. The prevalence of this infection has led researchers to describe it as a new “invisible epidemic,” particularly challenging to combat due to its transmission through spore-laden dust on hot, windy days.
While valley fever is usually not fatal, it can cause long-term health issues and severe pulmonary infections in some individuals, especially when diagnosis is delayed. In 2023, California reported the second-highest number of cases on record, with over 9,000 cases statewide. Subsequent years have shown a consistent increase, with higher numbers reported in the first part of 2025 compared to 2024.
The California Department of Public Health closely monitors valley fever cases to track trends and understand the populations most affected. Data updates show over 4,000 cases reported in the state between January and April, signaling a significant uptick compared to previous years.
Across the southwestern US, Arizona witnessed a 45% increase in valley fever cases, with nearly 4,000 new infections reported. California has also seen rising numbers for the past two years, surpassing previous records by October 2024. This fungal disease can cause respiratory symptoms and severe lung damage in some individuals, emphasizing the importance of early detection and treatment.
