Valley fever researchers have developed a vaccine—for dogs
The milestone is viewed as a stepping stone toward vaccinating humans.
Each year, the fungal disease valley fever infects tens of thousands of people in the American Southwest. Studies suggest infection rates could be even higher among dogs, however, and researchers in Arizona are now announcing progress on a canine valley fever vaccine.
Valley fever is caused by a fungus that grows in arid soil. Fungal spores can become airborne due to wind, construction or other activities that disrupt the soil, and inhaling the spores can lead to an infection in the lungs that can spread throughout the body if not treated promptly. Around half of those who develop an infection overcome it without ever knowing they had it, but symptomatic cases can resemble anything from mild flu to pneumonia to lung cancer. In rare cases, the disease can be fatal, or it can spread to other parts of the body and require life-long treatment.
Researchers estimate the disease’s financial burden annually tops $700 million in California and $736 million in Arizona, between direct and indirect costs including medical care, lost work time, and disability payments. In 2019, more than 19,300 cases of valley fever were reported in those two states alone, and the Centers for Disease Control and Prevention estimates the disease kills 200 Americans each year.
The disease burden may be significantly higher among dogs, suggests Dr. John Galgiani, a professor of medicine at the University of Arizona College of Medicine Tucson and director of the university’s Valley Fever Center for Excellence. “It’s, we think, roughly three times as great a problem for dogs as it is for humans,” he said. “If you talk to any of the veterinarians in areas where valley fever is common, they will tell you lots of stories about very bad infections in dogs and other pets too.”
Now, Galgiani’s team has developed a canine valley fever vaccine. In a peer-reviewed scientific study published online last month, he and his co-authors write that all dogs that received the vaccine during clinical trials were protected against significant disease. “If you vaccinate a dog and then infect them with very virulent strains of this fungus, they’re completely protected,” he said. “These are very exciting results.”
Clinical trials involved 30 dogs, broken into groups that received two vaccine doses spaced 28 days apart, one dose, or a placebo, before being exposed to a virulent strain of the fungus. According to a scoring system based on symptoms and analyses of blood and tissue samples, unvaccinated dogs on average showed severe disease, while those that received two doses did not exhibit any indicators that would have required a visit to a veterinary clinic.
Vaccine development has been supported by the pharmaceutical company Anivive Life Sciences. With their interest, and with eventual approval from the U.S. Department of Agriculture, which regulates vaccines in non-humans, Galgiani is optimistic the vaccine could be on the market as soon as 2023.
As exciting as a canine vaccine is, however, it’s also a stepping stone to a vaccine that hits closer to home. “That’s where we’re headed now, to develop this vaccine to go to the FDA for clinical trials in humans,” Galgiani said.
He’s hopeful that having a canine vaccine in hand can help secure the more than $100 million necessary to conduct human clinical trials—an effort that had gotten off to a promising start earlier in the century but stalled nearly a decade ago due to a lack of funding.