For the past two decades, frogs around the world have been battling a deadly infection. The disease is caused by the chytrid fungus. It has driven nearly 200 frog species to extinction. In the western U.S., the fungus has wiped out more than 90 percent of the mountain yellow-legged frog population. Now scientists are testing a way to help this endangered species fight back.
Conservationists in California have been collecting mountain yellow-legged tadpoles from the wild and exposing them to small amounts of chytrid fungus. The young frogs get a mild infection, which helps strengthen their disease-fighting immune system against the illness. When released, these frogs will be better able to fight future chytrid infections.
“The technique is new and complicated, but letting the frogs go extinct was not an option,” says Jessie Bushell, the director of conservation at the San Francisco Zoo in California. Since the project began three years ago, Bushell and other scientists have seen the frogs’ survival rates increase.