The Lowdown
More than 65 percent of valley fever cases in the U.S. occur in Arizona.
Many people don’t know they’ve been infected, but some experience
symptoms including: fever, cough, headache, chest pain, rash, muscle
aches, joint pain and fatigue.
In rare cases, patients can develop: chronic pneumonia, meningitis and
infection in the bones and joints.
Valley fever is not transmissible between people or dogs.
It is the silent scourge of the Southwest. It hovers around hiking trails, veers through ventilation systems and hitches rides on haboobs. It’s been found in 1,000-year-old Sinaguan skeletons and in the archaeologists who unearthed them. It is the vicious little fungus among us: coccidioides, the cause of valley fever.
Highly endemic to Arizona and California, valley fever infects an estimated 150,000 people annually. Most mistake it for flu, but some develop debilitating symptoms, and about 500 die. All it takes to contract valley fever – or coccidioidomycosis – is inhaling one breath of “cocci” spores.
“Valley fever is strange,” says Dr. Bridget Barker, associate professor at the Translational Genomics Research Institute (TGen). “It’s the only fungal pathogen that frequently causes disease in healthy people, and why that [happens] is the big mystery we’re trying to solve. Why do some dogs or people that are otherwise perfectly healthy all of a sudden get such a devastating disease, and in some cases don’t recover?”
The time to answer that question is now. Incidence of valley fever has steadily increased over the last decade. And due to development, drought and climate change, the fungal infection is spreading across the West; it was recently found as far north as Washington. But scientists know little about coccidioidomycosis, and doctors frequently misdiagnose it. Tests have proved unreliable and require waiting until the infection progresses to potentially dangerous levels. It typically takes five months after a patient originally visits the doctor to get a diagnosis.
All that is about to change. In August, the U.S. issued a patent for the first definitive valley fever test. Developed by TGen and Northern Arizona University, the DNA-based detector gets a result in one hour.
“It’s really important because a rapid diagnosis can literally be the difference between life and death for certain patients,” says Barker, head of TGen’s Northern Arizona Center for Valley Fever Research in Flagstaff. The test is expected to be available in hospitals upon completion of FDA trials and FDA clearance later this year.
In addition, TGen scientists are searching for clues to valley fever’s modus operandi by scrutinizing a promising new place: doggie drool.
Consummate spore-sniffers, dogs commonly contract valley fever and experience severe symptoms at about the same rate as their bipedal besties. They share most genes with people but have greater genetic uniformity (due to selective breeding) and age quicker, making canine clinical trials faster than human trials. All of this – and perhaps a bit of nominative determinism – got Barker thinking that “maybe directly studying humans wasn’t the fastest way to get to the answer” about valley fever.
So she started Valley Fever P.A.W.S. (Prevention, Awareness, Working for Solutions). The online registry (tgen.org/vfpaws) asks pet parents to submit information about both healthy dogs and those affected by valley fever, to determine if some breeds are more susceptible. Selected participants will be mailed a kit and asked to send dog saliva samples. TGen’s scientists will run the drool DNA through gene sequencers, searching for spots in the canine genome linked with susceptibility or resistance. Next, they’ll look for similar hotspots in the human genome. The goal is to learn how the infection varies and how to identify the most vulnerable people so physicians can better treat the illness with antifungal medication.
Between April – when P.A.W.S. was first publicized – and July, more than 900 dog owners from across the country have registered. TGen hopes to reach 2,000 by the end of the year. Preliminary results reveal that about 30 percent of registered dogs are positive for valley fever, regardless of breed. If breed isn’t significant, then symptom variation must depend on other genetic differences, or on factors such as fungus type, season and location.
Whatever it is, Barker aims to get to the bottom of it. “I really want to understand all facets of this organism,” she says. “I want to understand the diversity on the pathogen side, the diversity on the host side, and the diversity in the environment.”
