NEWVILLE, Wis. -

Wisconsin biologists say the koi herpes virus that's killing thousands of common carp has spread and will continue to do so.

Laura Stremick-Thompson, a fisheries biologist at the state Department of Natural Resources, told The Janesville Gazette the die-off started at the Rock River in July, reached Lake Koshkonong last week and will probably arrive in Janesville and Beloit in the next few weeks.

The biologist said local residents have reported hundreds of dead fish downstream of Lake Koshkonong and upstream of the Indianford Dam. One man said he has picked up about 30 dead carp along the Lake Koshkonong shoreline.

Stremick-Thompson said the koi herpes virus affects carp like Ebola affects humans. She says the mortality rate of the virus can reach up to 80 percent.