A bunch of Cambodians believe that this tortoise is good luck. Not only good luck, they believe it has healing power.
From the story, "The tortoise is believed to be a guard of Buddha. Local faiths which believe in the healing powers of animals are fairly common in Cambodia."
If they dust the amphibian just right and pray real hard, it will fix them. That's what they believe.
It's more likely to be the incredible power of placebo that cures her, if anything.