UT Researcher Working To Unravel Aquatic Virus

Jun 20, 2014

Larval marbled salamanders in the Great Smoky Mountains National Park, killed by ranavirus.
Credit Matt Niemiller

Fish, turtles, frogs and other animals that live in or near Tennessee waterways are being threatened by a dangerous virus. University of Tennessee researcher Matt Gray and his colleagues around the world are trying to determine the extent of the disease, called ranavirus, and its often-fatal effects on the species it infects.

The evidence in Tennessee, Gray said, is mainly anecdotal so far.

"We talk to people who say, 'There used to be frogs here, and they're not here anymore," Gray said. But he added that a study in the United Kingdom showed frog populations falling 80 percent in the last decade.

Few studies of ranavirus have been conducted in the Southeast, but die-offs associated with the disease were reported in Tennessee, North Carolina, Georgia and more than 30 other states as of 2010.

Ranavirus affects cold-blooded animals, and is thought to have originated in fish. Outbreaks typically start out very small, then spread rapidly through a population, according to Gray's research. Mortality rates, he found, can clock in above 90 percent in some species. The Great Smoky Mountains region has been hit by multiple outbreaks over the last decade.

People have played an interesting and surprising role in the spread of ranavirus, as transporters of the virus.

“You can imagine a fisherman in the Smokies, fishing in Tennessee one morning, and going across the Appalachians and fishing in North Carolina in the afternoon, and basically carrying the virus on his or her boots," Gray said.

All this matters to humans, Gray said, because the creatures that live around wetlands act as a barometer for the health of those wetlands. The health and distribution of amphibians and other species that call Tennessee wetlands home can be diagnostic tool for researchers who want to understand how humans affect the local environment.

Stopping the spread of ranavirus has been a difficult code to crack. Gray said fellow researchers in other parts of the U.S. and the world have been working on a cure or treatment for infected animals, but so far, no such cure has emerged.