NEWCASTLE, Australia, Dec. 10 (UPI) -- Frogs in Australia and the United States may be recovering from a fungal disease that has decimated amphibian populations around the world, researchers say.

Between 1990 and 1998 the populations of several frog species in Australia plummeted due to chytridiomycosis infection, but a recent survey suggests the frogs are re-establishing themselves, NewScientist.com reported Friday.


"It's happening across a number of species," Michael Mahony at the University of Newcastle in New South Wales says.

Barred river frogs, the tusked frog and several tree frog species have returned to areas where they had almost disappeared, and some species have even reached pre-infection levels, Australian researchers say.

There are also signs of recovery in the United States.

Roland Knapp at the Sierra Nevada Aquatic Research Laboratory of the University of California says mountain yellow-legged frogs, once "driven virtually to extinction," are returning.

The big question is, are frogs now beating the fungal infection?

Knapp and Mahony have separately determined that recovering frogs are living with low-level infections of the fungus.

It is possible, they say, the fungus has weakened in the areas where frogs are recovering.

There is also evidence the frogs are evolving, Knapp says.

At Vanderbilt University, researchers found a population of Australian green-eyed tree frogs previously decimated by the fungus produced more antimicrobial peptides, which inhibit fungal growth, on their skin than a less affected population.

"It's quite likely that populations are adapting and developing better defenses," Vanderbilt researcher Louise Rollins-Smith says.