"More Awareness Needed as Climate Change Could Spread Valley Fever
The changing environment—urbanization, industrialization and climate change—is leading to the spread of Coccidioides. Until recently, the fungus that causes Valley fever lived mostly in the southwestern United States, but today clinicians throughout the country should keep an open mind about this condition (JAMA Insights 2025 Feb 20. doi:10.1001/jama.2024.27274).
'Valley fever is caused by Coccidioides, a fungus that prefers dry areas,' said Pamela S. Lee, MS, MD, of the Division of Infectious Diseases at Harbor-UCLA Medical Center, in Torrance, Calif. 'Valley fever refers to the San Joaquin Valley [in California], but also has ‘hot spots’ in Arizona and Texas.'
Coccidioides resides in soil, and its growth is thought to increase with heavy precipitation. In their paper, Dr. Lee and her colleagues discussed how several years of drought followed by the very wet storms in California in 2022-2023 led to 'record-high numbers of coccidioidomycosis in 2023.'
Climate change has already increased temperatures and evaporative demand (i.e., the propensity of air to drive evaporation from the land surface and bodies of water) in the U.S. These changes have increased drought severity and soil dryness in the American West, with further increases anticipated depending on future global warming trajectory,' Dr. Lee and her team wrote. 'Decreases in soil moisture and/or increasingly wide or frequent swings between dry and wet conditions may promote environmental settings increasingly favorable to Coccidioides growth and dispersion.'
Coccidioidomycosis occurs with inhalation of spores that emerge from the soil when areas dry out, explained John Galgiani, MD, a professor of medicine in infectious diseases at the University of Arizona College of Medicine–Tucson."
