Can a novel immunization strategy save mountain yellow-legged frogs from a deadly fungal plague?

Nature · Published 30 September 2026 · Updated 24 October 2026 Swipe more like this →

In short: A devastating fungus has decimated hundreds of amphibian species by destroying the very skin they use to breathe and hydrate. Now, researchers are testing a bold, last-ditch defense: immunizing frogs against the pathogen. By exposing them to the fungus and treating the infection, scientists hope to build a lasting biological shield.

The chytrid fungus has emerged as a global catastrophe for amphibians, claiming approximately 200 species. For the mountain yellow-legged frogs of California’s Sierra Nevada, the threat is existential. These animals rely on their skin for critical physiological functions, including respiration and the absorption of essential electrolytes like sodium and potassium. When the fungus invades, it compromises this vital barrier, leading to a cascade of symptoms that include skin sloughing and locked limbs. As the infection progresses over two to three weeks, the inability to regulate heart-essential minerals eventually triggers fatal cardiac failure.

To combat this, biologists Cherie Briggs and Mary Toothman at the University of California, Santa Barbara, pioneered an immunization approach. Their methodology involved rearing frogs from eggs and deliberately infecting them with the fungus. Once the frogs exhibited symptoms, researchers administered a liquid antifungal treatment to halt the disease. After the subjects recovered, they were re-exposed to the pathogen. The results were promising: all 20 immunized frogs survived the second encounter, suggesting that their immune systems had successfully learned to recognize and defend against the threat.

This breakthrough has moved from the laboratory to the field. Institutions like the San Francisco and Oakland zoos are now replicating these experiments, working to return dozens of immunized mountain yellow-legged frogs to their native alpine lakes. While the fungus continues to spread through water via motile, flagellated spores or direct contact between amphibians, this vaccination strategy offers a glimmer of hope for species pushed to the brink. Experts like Vance Vredenburg of San Francisco State University continue to monitor the situation, as this intervention represents a critical effort to preserve biodiversity in the face of an ongoing, microscopic apocalypse.

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