Chicago ? A deadly fish virus has been found for the first time in southern Lake Michigan and an inland Ohio reservoir, spurring fears of major fish kills and the virus’s possible migration to the Mississippi River.

The Illinois Department of Natural Resources invoked emergency fishing regulations June 30 to stop the spread of viral hemorrhagic septicemia (VHS), often described as “fish Ebola,” which was found in round gobies and rock bass tested at a marina near the Wisconsin border in early June.

A few days earlier, the virus was detected in round gobies and yellow perch just outside Milwaukee. And weeks earlier, muskellunge in the Clear Fork Reservoir north of Columbus, Ohio, tested positive for the virus. That was the first time the virus was found in a waterway outside of the Great Lakes basin.

The virus attacks saltwater fish off the coasts of Europe, Japan and North America. It was first found in the Great Lakes in 2005. Officials say it was probably transported in the ballast water of the oceangoing freighters that enter the lakes through the St. Lawrence Seaway.

In 2005 and 2006, VHS caused major fish kills in Lake Ontario, Lake Huron, Lake Erie and Lake St. Clair, and it was found in northern Lake Michigan. State and federal officials, however, took immediate steps – such as banning the transporting of fish and bait among lakes – that limited the spread of the virus in 2007.

But this year’s virus detection in Wisconsin, Illinois and Ohio are of particular concern, as the virus was never before seen in those areas and all are routes to the Mississippi River, through the Chicago Sanitary and Ship Canal and the Ohio River. Officials worry that if VHS finds its way into the Mississippi, it will be carried by fish to other rivers and to hatcheries throughout the Midwest and much of the South.