ASOTIN -- The parasite that causes whirling disease has been found in wild Washington trout for the first time, the Washington Department of Fish and Wildlife announced today.

The parasites were found in rainbow trout in the Grande Ronde River and a tributary, Cottonwood Creek. The parasites may have entered Washington waters from the Oregon portion of the Grande Ronde.

The department is asking fishers, boaters and others to clean their boats and equipment to prevent the spread of the parasite which disables young rainbows and makes them vulnerable to predators. The department exercises great care to ensure the parasite does not enter its hatcheries.

"This discovery of the whirling disease parasite in some wild trout in Washington waters is unfortunate but not surprising," said Bern Shanks, director of the Department of Fish and Wildlife. "We don't think it will become a major problem if everyone who uses our lakes and rivers exercises good judgment to prevent the spread of the parasite."

The parasite, named Myxobolus cerebralis, invades the cartilage of young wild trout and salmon and may cause skeletal deformities and nerve damage. The nerve damage causes fish to appear to chase their tails in a whirling fashion. Diseased young fish afflicted with the parasite are very vulnerable to predators. The parasite does not afflict older fish because their cartilage skeletons have turned to bone.

The parasite is transmitted to fish from small worms that live in the sediments of streams and ponds, according to Kevin Amos, manager of the Department of Fish and Wildlife's fish health division.

Because the infection is transmitted from small, mud-dwelling worms, the department is asking fishers and other recreationists to:

• Remove all mud from boats, vehicles, anchors, trailers, waders and boots after leaving a body of water