Study: Longer, Drier Summers Extend Valley Fever Transmission in California
- 3 min. read ▪ Published
A new study led by researchers at UC Berkeley reveals that longer, drier summers in California can extend the transmission season of Valley fever, a fungal disease that is emerging across the southwestern U.S.
Cases of Valley fever in California typically rise in the late summer and decline in the winter. The study, published today in the Journal of the Royal Society Interface, finds that shifts in seasonal rainfall patterns—such as those anticipated with climate change—shift the start of the transmission season earlier, and prolong its duration.
Valley fever, or coccidioidomycosis, is caused by inhaling spores of the fungus Coccidioides, which is found in arid soils of the southwestern United States. The spores can become airborne when soil is disturbed by wind, construction, or other activities. California has seen record-breaking Valley fever incidence in recent years, raising concerns that climate change may further exacerbate the disease’s spread. Symptoms of Valley fever range from fever, cough, and chest pain to severe complications in some individuals, including pneumonia and meningitis.
“Climate change in California is expected to lead to drier spring and fall seasons and heavier winter rains. Our study found that these prolonged dry seasons can extend periods of high Valley fever risk,” said Simon Camponuri, a doctoral student in Environmental Health Sciences who led the research at UC Berkeley.
Researchers analyzed historical Valley fever case data alongside climate records to examine how temperature and precipitation patterns impact the timing and duration of transmission seasons. Their findings suggest that drier springs accelerate the onset of transmission seasons and drier falls delay the end of the transmission season.
“Our findings help clarify the relationship between seasonal rainfall patterns and Valley fever seasonal dynamics,” said Camponuri. “As climate change alters the timing and intensity of precipitation in California, we see longer high-risk periods for Coccidioides exposure.”
The findings have significant implications for public health preparedness and disease surveillance. “Understanding the link between climate variability and Valley fever season timing can help us target interventions, such as raising awareness among at-risk populations and improving diagnostic testing during peak transmission periods,” said Justin Remais, professor at UC Berkeley School of Public Health and principal investigator of the study. “Healthcare providers should be especially vigilant during and following prolonged dry seasons, as these periods may correspond with heightened disease transmission.”
As climate change reshapes environmental conditions in California, researchers emphasize the need for proactive public health strategies. “Our findings emphasize the importance of adapting public health mitigation strategies to changing climate conditions,” said Camponuri. “By understanding shifts in transmission season timing, we can take proactive steps to warn the public about increases in disease risk when they are most likely to occur.”