NEWVILLE, Wis. (AP) -

The koi herpes virus that's expected to kill thousands of common carp has spread from Rock River to Lake Koshkonong, and will likely hit Janesville and Beloit in the next few weeks, a Wisconsin biologist said.

Laura Stremick-Thompson, a fisheries biologist at the state Department of Natural Resources, told The Janesville Gazette 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.

The koi herpes virus affects carp like Ebola affects humans, according to Stremick-Thompson, with a mortality rate that can reach up to 80 percent. She said the virus only affects koi species, which include common carp, and was probably spread by a domesticated koi fish that was abandoned in the Rock River.

This outbreak marks the first time the virus has been reported in Wisconsin waters, but Stremick-Thompson said now it's here to stay.

"Hopefully, this virus will take a really large bite out of the carp population. They're very destructive to the overall habitat," said Brian Christianson, chairman of the Rock-Koshkonong Lake District.

But future outbreaks shouldn't be as bad because survivors will build immunity to the virus and reproduce, Stremick-Thompson said.

"It's not going to kill all the carp. It's really just creating a very bad situation for our recreational water users," she said.

The state Department of Natural Resources, the lake district and Rock County Health Department are not responsible for cleanup, so people may be deterred from participating in activities involving the affected water.