UW research collaboration discovers new virus infecting bald eagles

A microscopic image of a liver from a bald eagle that died from Wisconsin River Eagle Syndrome. The large white spaces demonstrate tissue damage characteristic of the disease. (Marie Pinkerton)
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MADISON, Wis. (WMTV) Researchers have discovered a previously unknown virus infecting nearly a third of America's bald eagle population.

Scientists at UW-Madison, the U.S. Geological Survey National Wildlife Health Center, and the Wisconsin Department of Natural Resources found the virus while searching for the cause of Wisconsin River Eagle Syndrome(WRES).

The disease affected bald eagles near the Lower Wisconsin River. WRES was first described in the 1990s. Observers near the river spotted eagles vomiting or staggering, and all of these birds either succumbed to the disease or were euthanized.

The researchers published their findings Oct. 18 in the journal Scientific Reports.The newly identified bald eagle hepacivirus (BeHV) may contribute to the fatal disease.

The virus is related to human hepatitis C virus, which causes liver damage in people, and some birds with BeHV show similar effects.

Tony Goldberg, a UW-Madison professor of pathobiological sciences in the School of Veterinary Medicine, led the study. He collaborated with LeAnn White at the USGS National Wildlife Health Center and Sean Strom at the Wisconsin Department of Natural Resources.

"Everything was pointing toward some unknown virus, but standard diagnostic techniques couldn't find one," said Goldberg.

Goldberg's lab analyzed liver tissue from nine birds diagnosed with WRES. The team first spotted the new virus in a bald eagle collected in 2002 in Sauk County.

Testing 47 eagles from 19 states across the contiguous United States, the researcher team found that 32 percent harbored BeHV. Researchers found the virus in seven states, including several in the Midwest, but also in states as far apart as Washington and Florida.

Researchers said the virus and the syndrome do not appear to endanger the resurgence of the bald eagle, which was removed from the endangered species list in 2007.There are now about 1,700 nesting pairs in Wisconsin.

“We don’t think this virus is having a serious impact on the bald eagle population, but the fact that WRES is an unknown condition keeps our interest,” said Strom, an environmental toxicologist with the DNR. “This study is another piece of the puzzle. Hopefully we can find more pieces and figure out what is happening.”

This study has opened our eyes to glaring knowledge gaps about infection in a species of great national importance,” said Goldberg. “It’s a more complicated story than we thought it might be at first, but that makes it more interesting.”

To learn more about the research process, read the original story here