Researchers pinpoint spread of deadly frog fungus

March 12, 2012 7:09:51 PM PDT
For more than 15 years, biologists have been baffled by a mysterious fungus that has killed entire species of frogs and amphibians around the planet. They've identified the fungus, but only now have they been able to figure out how it spreads.

It's an environmental preserve, Mori Point, a perfect getaway wedged between the Sharp Park Golf Course and a Pacifica suburb. It's a place where, if you look closely at the ponds, you can see frog eggs; where at night, residents hear them.

Natalie Reeder, who just earned her master's degree from San Francisco State University, is looking for one type of frog in particular. Based on the noise they make, the name is fitting -- chorus frog.

"They're one of the smallest frogs in California, and one of the loudest," Reeder said.

And now, thanks to research she has just published, it's also the most interesting to anyone familiar with implications of the chytrid fungus. That would include her professor, Dr. Vance Vredenburg.

"We are studying a disease that's unheard of in recorded history, in a sense that's it's had a bigger impact on vertebrates than any other disease ever recorded," he said.

Scientists only discovered the chytrid fungus 15 years ago. It has been killing amphibians around the world. One of the major questions: how does the fungus spread?

On most amphibians, chytrid fungus covers the skin, essentially suffocating them to death. But chorus frogs grow the fungus in patches, allowing them to breathe around it -- a mixed blessing.

"Well, since the other frogs get sick and die quickly, they don't have an opportunity to carry the disease to new areas where the frogs aren't sick," Reeder said. "But since chorus frogs don't get sick, they can move from one population to another and spread the fungus to new areas."

You might wonder why this research has relevance beyond amphibians. Well, biology is biology, no matter what the host.

"What happens if the next epidemic is mammals? You have the same factors taking place here. You have the pathogen that's being spread from host to host to host," Vredenburg said. "We're looking at those transmission dynamics. So those types of things are the same across all diseases."

In short, we may need to apply this research to humans someday.


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