Valley Fever Fungus Could Expand as U.S. Climate Changes

The fungus that causes Valley fever could gain new territory as climate change alters conditions across the U.S.

More than 200,000 people in the U.S. get Valley fever every year. This potentially serious lung infection, caused by a fungus called Coccidioides, is endemic in much of the Western United States.

Coccidioides lives in the soil where temperatures and moisture are ideal for the fungus to grow and then break down into spores. When humans breathe in those spores, they can become sick. 

Some states where Coccidioides and Valley fever are common, like California and Arizona, track it at the county level. But a new study in The Lancet Planetary Health indicates that the fungus also lives and causes illness in areas that do not track it. In this study, researchers from Emory University’s Rollins School of Public Health used county-level surveillance data and hospital records to determine which areas of the U.S. currently have the right conditions for Coccidioides to live and project where it could expand in the future.

Key Takeaways

• The Coccidioides fungus is likely endemic in areas of the country that don't currently conduct surveillance for Valley fever, like Texas.
• As climate conditions shift across the U.S. in the future, the fungus will likely be able to expand its environment further north and east.
• This expansion could put more than 20 million more people at risk of contracting Valley fever.

What This Means

“Valley fever remains unfamiliar to much of the country, but it poses a significant public health challenge where it occurs,” says Aniruddha Deshpande, PhD, the study’s lead author and a postdoctoral researcher at Rollins. “Our findings suggest that climate change could expand the geographic range of conditions favorable to the disease, placing millions of additional people at potential risk in the coming decades. Identifying where that risk may emerge can help public health agencies strengthen surveillance, improve preparedness, and support earlier detection.”