The tapeworms could spread to gamefish and other wildlife, said Barbara Shields, an assistant professor of fisheries science with Oregon State University.

Scientists are examining whether the tapeworms could infect people.

The giant tapeworm, Ligulus intestinalis, has spread to two kinds of fish in which it has never been found before, an indication that it could jump to more new hosts, Shields said.

One was nearly 3.5 feet long and may be the longest such parasite ever discovered in North America.

The other new tapeworm, Schistocephalus solidus, usually infests fish one worm at a time but up to 12 are being found in each infected fish in central Oregon.

The tapeworms have been found in Mirror Pond in downtown Bend, in irrigation canals between Bend and Madras and in other waterways, including Lake Billy Chinook.

Researchers are unsure how the tapeworms came to Central Oregon.

"I get a lot of calls from the public asking whether they should stop eating fish and swimming in local waters. I tell them not to worry," Shields said.

The Schistocephalus tapeworm likely arrived when its host fish, the three-spined stickleback, was introduced into the Deschutes Basin.

The Ligulus tapeworm has been found in the chiselmouth, the northern pike minnow and the bridgelip sucker.

It is the first time the Ligulus has been found in the chiselmouth and bridgelip sucker. Shields said the Ligulas jump to new hosts was a "red flag" for possibly infesting other species.

The Ligula was discovered in Central Oregon in 1999 when two OSU researchers were snorkeling in Lake Billy Chinook and saw a sucker fish with a large tapeworm crawling out of the fish's side.

The worms sometimes have little impact on the fish, but can cause massive fish kills.

Shields herself once contracted a related species of tapeworm.