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CORVALLIS, Ore. - Only one kind of tick in Oregon and most of the western United States carries Lyme disease, but distinguishing it from the other three species that prey on humans can be difficult.

For that reason, Philippe Rossignol, professor in the fisheries and wildlife department at Oregon State University, recommends first contacting OSU Extension county offices to help identify ticks. If they are unable to help, you can submit samples to the OSU Insect ID Clinic, which identifies what kind of tick has been removed from humans or pets. The clinic cannot, however, identify if the tick carries the Lyme disease bacterium. The service is online at bit.ly/cnOydr

About 20 species of hard ticks are found in Oregon, but only four are known to prey on humans: western black-legged tick, Rocky Mountain wood tick, American dog tick and Pacific Coast tick.

The western black-legged tick is the only known carrier of Lyme disease in Oregon. The other known vectors of Lyme disease in the United States are the deer tick in the eastern part of the country and the eastern black-legged tick in the southeast.

"It is believed that only about one to five percent of western black-legged ticks actually carry the bacterium responsible for Lyme disease," Rossignol said. "Both adults and immature ticks transmit the disease, and they must be attached to the host for 24-48 hours before they can pass the bacterium to humans.

"In Oregon, adult ticks are active primarily in the spring and early summer, but also can be found in the fall," Rossignol said. "When ticks seek a host, they perch on low branches of shrubs or tall grass and wait to attach to a passing bird, animal, human, or even reptile."

A publication called "Identifying Adult Hard Ticks Commonly Found on Humans in Oregon," provides additional information and the following advice on how to remove attached ticks as soon as possible. It is online at bit.ly/8rmc3

•    If possible, have someone else remove the tick from your body.
•    Use tweezers or forceps rather than fingers.
•    Grasp the mouth parts or head end of the tick as close to the skin as possible.
•    Gently pull the tick straight out, steadily and firmly.
•    The mouth parts are barbed like a harpoon and might break off in the skin. If so, don't be concerned. They do not carry the bacterium and are no more harmful than a sliver.
•    Wash hands and the bite area with soap and water; apply an antiseptic to the bite area.
•    Keep the tick for identification if disease symptoms occur later. Place the tick in a small container of alcohol labeled with the date removed and the place it was picked up.
•    Use the same procedures and precautions when removing ticks from pets.