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To Save Frogs From a Horrifying Fungus, We Might Have to Vaccinate Them

Amphibians are dying out at a breakneck pace. It's time to get them up to date with their shots.
Image: Wikimedia Commons

It's no secret that global biodiversity is shrinking at an alarmingly quick clip. But few biological classes have it worse than amphibians, which are being edged out of existence at 211 times the background extinction rate. Of the approximately 6,000 amphibian species still hanging in there, a third of them are threatened.

There are many reasons for the dramatic loss of amphibians—climate change, habitat loss, UV radiation among them—but possibly the nastiest killer of them all is chytrid fungal disease. Fortunately, researchers based out of the University of South Florida have discovered multiple ways to successfully immunize amphibians against strains of the fungus. The team's paper was published in Nature on July 10.

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"This study found that frogs could actually develop acquired immunity if they were previously exposed to either live or dead fungus," co-author Taegan McMahon explained to me. "It's possible we might be able to induce acquired resistance in captive bred frogs and release them, or we might be able to possibly expose ponds in the wild. But at this moment we do not have any true idea of the broader implications or whether any of these management plans are feasible."

The team experimented with a few different methods of "vaccinating" amphibians against the crytrid strain Batrachochytrium dendrobatidis. They discovered that amphibians could develop immunity to the fungus after repeated exposure, and that crucially, amphibians exposed to a dead version of the fungus acquired a comparable immunity as those exposed to a live version. They also found that frogs could learn how to avoid the fungus after repeated exposure.

But as McMahon pointed out, there is still a lot of research to be completed before biologists can start flushing amphibian habitats with dead fungus. Co-author Jason Rohr provided a point-by-point summary of the team's next steps: First, Rohr and McMahon need to determine how long immunity lasts in amphibians. They also need to figure out the concentrations and exposure time to dead fungus that will result in sufficient acquired resistance.

Then, they hope to induce acquired resistance at the tadpole stage, develop a predictive model for chrytid dynamics that includes acquired resistance, and finally, "release dead chytrid in the wild to see if it can reduce chytrid abundance and enhance amphibian population growth."

"Theoretically it could help amphibians globally," Rohr told me. "However, it will depend on how much amphibian species and chytrid strain variation there is, how long the immunity lasts, whether we can immunize tadpoles, and how much any immunization improves frog survival.  Until we know answers to these questions, the value of a 'vaccination' campaign remains equivocal."

Though the research is in its early stages, the idea of preventing amphibian pandemics with regular immunization is exciting. And amphibians could really use the break.