Introduction to Valley Fever
For man’s best friend, pet owners often go to great lengths — whether that’s doggy daycare and specialty pup chow, or late nights at the vet running tests that drain bank accounts. Now, a new study by researchers from UC Davis and UC Berkeley has found a way our canine companions can help us, offering a unique glimpse into Valley fever — a disease that has been growing steadily throughout California and the American West.
Understanding Valley Fever
Valley fever is a disease with a foothold in the American Southwest and Washington caused by a fungus that takes root in the lungs, where it can cause pneumonia. While those who get sick generally get better on their own, some require special treatment, and in rare cases, the disease can spread to the bones, skin, and even the brain. The disease is not contagious; instead, it spreads when humans and other animals inhale tiny spores from the fungus Coccidioides that are hidden in dust particles and carried in the air.
The Rise of Valley Fever in California
Since the start of the millennium, cases in California have ballooned from around 1,400 cases in 2001 to over 9,000 cases in 2023, according to data from the California Department of Public Health, disproportionately affecting those who work in the soil like farmworkers and construction workers. Often the disease is misdiagnosed, and delays in diagnosis can make treatment more difficult. All these factors mean that tracking the disease, spreading awareness, and taking preventative measures where it takes root are essential to keeping people safe. But the fungus is tough to track by testing in the soil or the air.
The Role of Dogs in Tracking Valley Fever
That’s where dogs come in. Humans and dogs hang out a lot. A little less than half of households in the U.S. have a dog, and these curious creatures tend to root around in the dirt and dust, making them more likely to come in contact with the disease. They also get the disease in ways that are similar to us, contracting pneumonia that in rare occasions can spread beyond the lungs. Because of this, the researchers decided to see whether Valley fever in dogs lined up with where the illness showed up in humans.
Study Findings
The team started with more than 2 million tests submitted by vets to labs that tested for Valley fever, and homed in on tests of dogs from 2012 to 2022. The tests represented more than 800,000 hounds across the country. They found that the cases in dogs spread over time, with most centered in Arizona, followed by California in a distant second. When they looked at how the disease grew over time in those two states, they found that when more dogs got sick, humans also saw an uptick in Valley fever. When comparing the spread of the disease, they also noticed that hotspots for Valley fever in dogs were likely to also be hotspots for humans.
Expert Insights
“The study findings present an important advance for both public health and animal health,” said Renata Ivanek, a professor at Cornell University who studies human and animal infectious disease and was not involved with the study. While she notes that the correlation between dog and human cases was “not perfect,” she argues that the method benefits by using information that is already out there. “The elegance of this approach is that diagnostic testing is already done,” she said.
A man walks his German Shepherds while at Shell Ridge Open Space in Walnut Creek, Calif., on Thursday, May 1, 2025. According to a paper recently published by researchers from the University of California, Davis and Berkeley, knowing when and where dogs got sick with valley fever could give us clues to where humans might also contract the disease. (Jose Carlos Fajardo/Bay Area News Group)
Clyde, a five-year old Goldendoodle, rolls in the dirt while on a walk with her owner Victoria Conway, of Walnut Creek, at Shell Ridge Open Space in Walnut Creek, Calif., on Thursday, May 1, 2025. According to a paper recently published by researchers from the University of California, Davis and Berkeley, knowing when and where dogs got sick with valley fever could give us clues to where humans might also contract the disease. (Jose Carlos Fajardo/Bay Area News Group)
A dog runs on the trail in front of her owner at Shell Ridge Open Space in Walnut Creek, Calif., on Thursday, May 1, 2025. According to a paper recently published by researchers from the University of California, Davis and Berkeley, knowing when and where dogs got sick with valley fever could give us clues to where humans might also contract the disease. (Jose Carlos Fajardo/Bay Area News Group)
Future Implications
While this could help public health researchers in places where Valley fever has already taken root, it also might tell us where to look next. In states like Texas and Idaho that don’t regularly report cases of Valley fever in humans, the tests from dogs showed significant cases. This means that the study, and the canine data, could serve as a warning sign for where humans should look out for the illness. “I think this really suggests that there’s public health value in knowing what’s going on with the dogs in the area,” said Peter Rabinowitz, who researches public health at the University of Washington and was not involved in the study.
Conclusion
The study serves as a reminder of how connected human health is to that of animals and the environment, pointing out that the spread of Valley fever may be sped up by climate change and even wildfires. Given this, the researchers argue that narrow approaches to health won’t be enough to solve “increasingly complex problems” in health and the environment. Instead, the study serves as an invitation to a wider view of health that could mean better outcomes for humans, their environment, and their furry friends. “We need to have that very broad lens,” said Jane Sykes, the veterinary researcher at UC Davis who led the study.
FAQs
- Q: What is Valley fever?
A: Valley fever is a disease caused by a fungus that takes root in the lungs, where it can cause pneumonia. - Q: How is Valley fever spread?
A: The disease spreads when humans and other animals inhale tiny spores from the fungus Coccidioides that are hidden in dust particles and carried in the air. - Q: Can dogs get Valley fever?
A: Yes, dogs can get Valley fever, and their cases can help track the disease in humans. - Q: How can tracking Valley fever in dogs help humans?
A: Tracking Valley fever in dogs can help identify geographical areas where humans might also contract the disease, aiding in public health efforts to spread awareness and bolster prevention.
Originally Published: May 6, 2025 at 3:47 PM EDT
