Still, more than half of the treated, free-flying bats in Hoyt's experiment died, meaning the Pseudomonas fluorescens probiotic is far from a miracle cure. Hoyt notes it may be possible to modify the dose or combine it with other treatments. Scientists are testing other options, including a vaccine, which a recent study found effective in captive bats. It may also be possible to use an antifungal agent to clean the caves prior to winter, enhancing the bats' odds. "I think it will take a lot more than just this [probiotic], there's no silver bullet," says Hoyt. Still, he adds, "this definitely is one more tool that we have to try to reduce disease impacts."