A fast-spreading virus recently killed thousands of round gobies near Milwaukee, and officials fear the same fate may await fish elsewhere in Lake Michigan.

The gobies washed ashore May 28 after dying from viral hemorrhagic septicemia, according to the Wisconsin Department of Natural Resources.

The virus causes fish to hemorrhage and suffer organ failure.

The Milwaukee incident made Lake Michigan the fourth of the five Great Lakes to suffer a large VHS-related fish kill.

Only Lake Superior has avoided the disease. It has killed millions of fish in lakes Erie, Ontario and Huron and threatens the Great Lakes' $7 billion sport and commercial fisheries.

VHS has not shown up in Michigan's portion of Lake Michigan, said state officials quoted by the Muskegon Chronicle Wednesday.

"Was the Wisconsin die-off surprising to us? Not at all," said Jim Dexter, Lake Michigan basin coordinator for the Michigan Department of Natural Resources. "We knew VHS was present in Green Bay last year, and we know it's now available to be transferred to other species."

Other than the Great Lakes, VHS also has been confirmed in Budd Lake, near the mid-Michigan community of Harrison.

VHS has killed or infected 40 species of Great Lakes fish, according to federal records. Among the affected species were lake trout, walleye, perch, whitefish and salmon.

Once the virus invades a lake or river, there is no way to prevent it from killing fish. Fish can absorb VHS from the water or contract it from other fish.

Discovered in Lake Ontario in 2005, VHS is one of 185 foreign species in the Great Lakes.

The source of VHS in the lakes has not been confirmed. Experts say it could have been imported by fish, birds, ocean freighters or anglers moving contaminated bait fish between lakes.

Michigan passed new rules last year restricting the movement of bait fish from one body of water to another.