Researchers Find Disinfection To Stop VHSV Transmission

Feb 2: A disinfection solution presently used for salmon eggs also prevents transmission of the virus that causes viral hemorrhagic septicemia virus (VHS or VHSV) -- one of the most dangerous viral diseases of fish -- in other hatchery-reared fish eggs, according to new U.S. Geological Survey-led research. VHSV has caused large fish kills in wild fish in the U.S., especially in the Great Lakes region, where thousands of fish have died from the virus over the last few years. The disease causes internal bleeding in fish, and although in the family of viruses that includes rabies, is not harmful to humans. Thus far, the virus has been found in more than 25 species of fish in Lakes Michigan, Huron, Erie, St. Clair, and Ontario, as well as the Saint Lawrence River and inland lakes in New York, Michigan and Wisconsin. On January 27, 2010, researchers from Cornell University reported that VHSV had been discovered in for the first time in fish from Lake Superior [See WIMS 1/29/10].

Mark Gaikowski, a USGS researcher who led the USGS and U.S. Fish and Wildlife Service research team indicated that effective disinfection methods are critically important to natural resource agencies that collect eggs from wild fish stocks and private aquaculture because the spread of the virus to a fish hatchery "could be devastating." He said, "If VHS virus is introduced into the aquaculture industry, it could lead to trade restrictions, as well as direct economic losses from the disease."

USGS and USFWS researchers tested the effectiveness of using iodophor disinfection in walleye and northern pike eggs and found that it eliminated active virus from fertilized eggs. Iodophor disinfectant solutions contain iodine formulated for use on fish eggs. The researchers also found that although some of the disinfection treatments reduced hatch, iodophor treatment at 90 minutes after fertilization occurred did not alter egg hatch or fry development. USGS said in a release that experts fear the disease could potentially spread from the Great Lakes into new populations of native fish in the 31 states of the Mississippi River basin. Regulatory agencies in the United States and Canada have already placed restrictions on the movement of fish or fish products that could pose a risk for the spread of VHS virus to regions outside of the known geographic range.

Access a release fro USGS with links to more information on the VHSV (click here).