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Valley fever vaccine for dogs shows promising results, first step toward human trials

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Valley fever vaccine for dogs shows promising results, first step toward human trials

  • A scanning electron microscope image of Coccidioides spherules. A spherule is the parasitic form of the fungus that grows inside the human or animal host.
    Bridget Barker/NAUA scanning electron microscope image of Coccidioides spherules. A spherule is the parasitic form of the fungus that grows inside the human or animal host.

A new Valley fever vaccine for dogs appears to provide a safe and effective defense against the fungal illness that sickens thousands of pets in Arizona each year, new research by an international team of scientists shows, and marks a significant milestone that could lead to a similar vaccine for humans.

The study, led by researchers from the University of Arizona Valley Fever Center for Excellence, was a first-of-its kind experiment that showed strong protection for canines injected with two doses of the vaccine. The commercial veterinary version of the vaccine could be available within the next two years, researchers said. 

The findings have significant implications for a disease now on the rise in Arizona and across the Southwest. Researchers expect the range of the fungus to spread because of climate change, making the need for an approved vaccine that much more urgent. This new study paves the way for further development of the vaccine to eventually prevent infections in people.

Valley fever is a respiratory illness caused by a fungus in the genus Coccidioides, which is  found in soil and dust throughout the Southwest and California. The fungus, which causes coccidioidomycosis, or Valley fever, most often causes flu-like symptoms such as fever, body aches and coughing. In severe cases, when the disease spreads beyond the lungs in what’s known as disseminated Valley fever, the illness can cause lifelong debilitating illness and even death.

The disease killed 39 people in Arizona and sickened thousands more in 2019, according to the Arizona Department of Health Services. And so far in 2021, more than 9,000 residents here have been diagnosed with Valley fever, representing about two-thirds of all cases in the U.S.

“A veterinary vaccine in and of itself is a huge boon,” said the study’s lead author, Dr. Lisa Shubitz, a veterinarian and researcher at the Valley Fever Center for Excellence, adding that the new research and vaccine “is also a stepping stone to humans.”

The recent study relied on experiments in which 30 dogs were purposely infected with Coccidioides in a lab. Dogs that received two doses of the vaccine were significantly more protected from the fungus compared to unvaccinated dogs. Researchers also found that the vaccine was “well-tolerated,” meaning side effects at the injection site were not severe and there were no adverse reactions such as fever, pain or vomiting.

Researchers have tried for decades to develop a Valley fever vaccine for dogs and humans, but results to date have shown certain types of vaccine are ineffective and cause serious injection site reactions. It’s not just Valley fever: No approved vaccine exists for any fungal disease. 

Because Valley fever is contracted by inhaling microscopic spores into the lungs, there are few available interventions that can prevent someone from contracting the disease. 

Recent AZCIR reporting revealed that little is known about who in Arizona is most impacted by this deadly pathogen, in part because of scant state and federal funding allocated to studying and mitigating the disease. State policies also limit workers’ compensation claims related to Valley fever, making it difficult to track where infections occur, adding further to a general lack of consistent data that’s collected and maintained when people are diagnosed. This is all despite research that indicates Valley fever is a growing problem in the U.S., especially in Arizona, and the most severe form of the illness, disseminated Valley fever, manifests disproportionately in people of color.

“They saw very dramatic protection in the dogs and I think that makes it very promising,” said Dr. Stuart Levitz, a professor at the University of Massachusetts Medical School who was not involved in the study. Levitz, who runs a lab that is working on a vaccine for another type of fungus, said the new study makes him feel optimistic, as it makes progress towards a human vaccine that “would save as many lives as the vaccines that we already get.”

In Arizona alone, Shubitz said thousands of dogs are diagnosed with Valley fever each year. In her veterinary practice, she is “inundated” with sick dogs with a Valley fever diagnosis. Dogs come in with symptoms of cough, fatigue and lack of appetite, she said, and sometimes Valley fever causes bone lesions or even blindness. 

“Dogs really suffer from this disease and their owners’ checkbook suffers,” Shubitz said. She anticipates dog owners would be eager to get their pets vaccinated, adding that they helped fund preliminary research through donations and fundraisers. That work helped the research team generate enough data to receive a National Institutes of Health grant that funded the latest study. 

The vaccine tested in the research is a live-attenuated vaccine, meaning it was created from an altered pathogen so it can’t become infectious, or sicken the host. Instead of causing infection, the vaccine gives the immune system the ability to preview the pathogen and better defend against a future infection.

“This is a live vaccine, so safety is a big issue,” said Dr. John Galgiani, a co-author on the study and director of the Valley Fever Center for Excellence. There are concerns a live vaccine could make some people or animals ill, but tests on mice without an immune system still did not result in disease, he added. 

For U.S. Department of Agriculture approval, which is necessary for veterinary vaccines, the next step is to conduct further experiments on dogs with the exact formulation of the vaccine that would be made publicly available, Galgiani said. The researchers are working with Anivive Lifesciences, a pet pharmaceutical company based in Long Beach, California, to bring the commercial version of the vaccine to market.

USDA approval for a dog vaccine will make a compelling case for funding vaccine development in humans, but creating and testing the Valley fever vaccine for people, Galgiani estimates, will cost $15 million to get started and between $150 and $200 million “to get to the finish line.”

Federal funding for Valley fever research can be hard to come by, researchers say, so the organism that causes it remains largely understudied. The illness is currently classified as an “orphan disease,” because there are fewer than 200,000 cases diagnosed in the U.S. each year

Earlier this month, U.S. Rep. Kevin McCarthy, R-Calif., introduced the FORWARD Act for the third time since 2018. The “Finding Orphan-disease Remedies With Antifungal Research and Development Act” is co-sponsored this session by Reps. Tom O’Halleran, D-Ariz., David Schweikert, R-Ariz. and Karen Bass, D-Calif. The bill seeks to provide $20 million per year for five years through the National Institutes of Health that would be dedicated to epidemiological and clinical research on fungal diseases, including treatments and vaccines for Valley fever.

This report was first published by the Arizona Center for Investigative Reporting.

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