Egg Disinfectant Prevents Transmission Of VHS

VHS has led to thousands of wild fish in the US, especially in the Great Lakes region, dying 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, Superior and Ontario, as well as the Saint Lawrence River and inland lakes in New York, Michigan and Wisconsin.

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, said Mark Gaikowski, a USGS researcher who led the USGS and US Fish and Wildlife Service research team.

"If VHS virus is introduced into the aquaculture industry, it could lead to trade restrictions, as well as direct economic losses from the disease," Mr Gaikowski noted.

USGS and USFWS researchers tested the effectiveness of using iodophore disinfection in walleye and northern pike eggs and found that it eliminated active virus from fertilised eggs. Iodophore disinfectant solutions contain iodine formulated or use on fish eggs. The researchers also found that although some of the disinfection treatments reduced hatch, iodophore treatment at 90 minutes after fertilisation occurred did not alter egg hatch or fry development.

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.