In May 2007, hundreds of freshwater drum -- also known as sheepshead -- turned up dead in Lake Winnebago and nearby Little Lake Butte des Morts, both inland lakes near Oshkosh, Wisconsin. The fish were splotched with red and their eyes were swollen and bulging. The Wisconsin Department of Natural Resources (DNR) launched a quick response and, working with the Wisconsin Veterinary Diagnostic Laboratory (WVDL), quickly learned that a deadly virus was responsible: viral hemorrhagic septicemia virus (VHSv) (image). First detected in the U.S. among freshwater fish in 2005 -- including muskellunge, perch, and walleye -- VHSv had already caused mass fish die-offs in the Great Lakes and several regional waterways connected to them. The DNR subsequently encouraged anglers and boaters to adopt practices that have helped slow the spread of VHSv into other inland lakes in Wisconsin, but a new study led by Dr. Tony Goldberg, Professor of Epidemiology and Pathobiological Sciences at the University of Wisconsin-Madison (UW-Madison) School of Veterinary Medicine (SVM), shows that the virus is still circulating in Lake Winnebago. It also shows that some fish actually survive VHSv infection, but could be sources of future infections. The new study was published in an open-access article in the September 2015 issue of the Journal of Clinical Microbiology. The article is titled “Temporal Variation in Viral Hemorrhagic Septicemia Virus Antibodies in Freshwater Drum (Aplodinotus grunniens) Indicates Cyclic Transmission in Lake Winnebago, Wisconsin. "It's still possible to transmit the virus to fish in other lakes," says WVDL Virology Section Head Dr. Kathy Toohey-Kurth, a member of the research team and a clinical professor at the SVM.
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