Ticks are present throughout Oregon, and understanding the species is important for safe outdoor activity. Ticks are arachnids that feed on the blood of mammals, birds, and reptiles, and they can transmit pathogens that cause illness in humans and pets. Awareness of their habitats and potential health risks allows residents and visitors to take informed precautions when recreating in forested or grassy areas.
Confirmed Tick Species in Oregon
Oregon is home to approximately 20 species of hard ticks, though only a few commonly feed on humans. The species of greatest concern is the Western Blacklegged Tick (Ixodes pacificus), the only known vector for Lyme disease in the state. Adult females are identifiable by their reddish-brown bodies and a dark dorsal shield, while males are almost entirely black.
Two other frequently encountered species belong to the Dermacentor genus. The Rocky Mountain Wood Tick (Dermacentor andersoni) is large and brown, with mottled gray or white markings on the male’s back. The American Dog Tick (Dermacentor variabilis) is reddish-brown and displays white or grayish markings on its dorsal shield. The Pacific Coast Tick (Dermacentor occidentalis) is also found, particularly in the southwestern region.
Geographic Distribution and Active Seasons
The distribution of Oregon’s tick species is influenced by the Cascade Mountain range. The Western Blacklegged Tick is primarily found in the western portion of the state, including the Coast Range, the Willamette Valley, and the Cascade foothills. Tick density is highest in the southwestern counties of Oregon.
The Rocky Mountain Wood Tick is most common east of the Cascades, inhabiting higher elevations and open grasslands. Tick activity typically peaks from spring through early summer, generally March to June. However, adult Western Blacklegged Ticks can remain active throughout the mild winter months, especially in coastal and low-elevation areas.
Disease Transmission Risks
Lyme disease is the most frequently reported tick-borne illness in Oregon. It is caused by the bacterium Borrelia burgdorferi, carried by the Western Blacklegged Tick. Transmission requires the tick to be attached for at least 36 to 48 hours, as only one to five percent of these ticks carry the bacterium in Oregon.
Lyme disease symptoms often begin with fever, headache, fatigue, and muscle aches. About 60% of patients develop the characteristic expanding red rash known as erythema migrans. The Western Blacklegged Tick can also transmit Anaplasmosis, a bacterial infection causing non-specific fever and headache symptoms.
The Rocky Mountain Wood Tick and the American Dog Tick can transmit Rocky Mountain Spotted Fever (RMSF). RMSF is a progressive illness beginning with high fever, headache, and a rash that appears on the wrists and ankles days later. The Rocky Mountain Wood Tick is also a vector for Tick Paralysis. This non-infectious condition is caused by a neurotoxin in the tick’s saliva, presenting as an ascending, flaccid paralysis that starts in the legs.
Prevention and Safe Removal Techniques
Effective prevention involves knowing tick habitats, which include tall grasses, brushy areas, and wooded habitats. When recreating, wearing light-colored clothing makes it easier to spot ticks before they attach. Tucking pant legs into socks and using DEET-containing repellents on exposed skin provides a layer of protection.
Applying products containing Permethrin to clothing and gear offers extended protection, as this insecticide kills ticks on contact. After spending time outdoors, shower within two hours and perform a thorough tick check on yourself, children, and pets. Tumble drying clothes on high heat for at least 10 minutes kills any hitchhiking ticks.
If a tick is found attached, safe removal requires fine-tipped tweezers. Grasp the tick as close to the skin’s surface as possible, gripping the mouthparts, not the body. Pull straight upward with slow, steady pressure, avoiding twisting or jerking.
After removal, clean the bite area and your hands with rubbing alcohol or soap and water. Never attempt to remove a tick using folk remedies like petroleum jelly, nail polish, or a hot match, as irritating the tick can increase the risk of disease transmission.