Washington state is home to several tick species, with different types concentrated on opposite sides of the Cascades. Ticks are most active during spring and early summer, and while overall disease risk remains lower than in the northeastern U.S., locally acquired tick-borne illnesses do occur here. Knowing which ticks live where, and what they carry, helps you take the right precautions whether you’re hiking the Olympic Peninsula or camping near the Columbia Basin.
Tick Species by Region
Washington’s tick population splits along a geographic line: the Cascade Mountains. On the west side and along the eastern slopes of the Cascades, the western black-legged tick is the primary species of concern. This is the tick responsible for transmitting Lyme disease and anaplasmosis in the state, and it thrives in forested and brushy areas typical of western Washington’s landscape.
East of the Cascades, two different species dominate. The Rocky Mountain wood tick and the western dog tick are both common in eastern Washington’s drier, more open terrain. These ticks can carry Rocky Mountain spotted fever and tularemia. If you spend time outdoors in both halves of the state, you’re dealing with different tick species and different disease risks depending on where you are.
Peak Season and Where You’ll Encounter Them
Tick activity in Washington peaks in spring and early summer. This lines up with when most people are getting back on trails, working in yards, or spending time in grassy and wooded areas. Ticks don’t jump or fly. They wait on vegetation with their front legs extended, latching onto anything that brushes past, a behavior called questing. Tall grass, leaf litter, shrubby understory, and the edges where forest meets open ground are prime tick habitat.
Activity tapers off in the hotter, drier months of late summer, though ticks can remain active year-round in milder parts of western Washington during warm winters. Dogs and other pets that move through brush and tall grass are frequent tick hosts and can bring ticks indoors.
Diseases Ticks Carry in Washington
Four tick-borne diseases have been documented in the state, each with different levels of confirmed local transmission.
Lyme Disease
Washington reports between 7 and 23 Lyme disease cases each year. Most of those result from tick bites people received out of state, particularly in the Northeast or upper Midwest where Lyme is far more common. The few cases acquired locally involve tick exposure on the west side of the Cascades, where the western black-legged tick lives. Local transmission is real but uncommon.
The hallmark early sign of Lyme disease is an expanding rash that often takes a bullseye shape, though it can also appear as a solid red or blotchy oval. The rash typically shows up within days to a month after a bite. Up to 30% of people with Lyme never develop or notice a rash at all. Other early symptoms mimic the flu: fatigue, fever, muscle and joint pain that moves around the body, swollen lymph nodes, and loss of appetite. On darker skin tones, the bullseye pattern can be harder to spot, and the rash itself may appear more purple than red.
Anaplasmosis
Anaplasmosis is transmitted by the same western black-legged tick that carries Lyme. Infected ticks have been collected in Washington, and the first human case likely acquired within the state was reported in 2022. The disease has also been diagnosed in numerous dogs statewide. Symptoms begin one to two weeks after a bite (sometimes up to three weeks) and include fever, chills, severe headache, muscle aches, nausea, vomiting, and diarrhea. When treated promptly, outcomes are good. Delayed treatment can lead to serious complications including organ failure, though death occurs in fewer than 1% of cases.
Relapsing Fever
Two forms of relapsing fever exist in Washington. Soft tick relapsing fever, spread by a different type of tick that lives in rodent-infested cabins and rustic shelters, has been confirmed in people with Washington-only exposure. Hard tick relapsing fever has been found in field-collected ticks in the state but hasn’t yet been linked to a human case acquired here. Both cause recurring episodes of high fever, headache, and muscle pain.
Rocky Mountain Spotted Fever and Tularemia
The wood ticks and dog ticks common in eastern Washington are known vectors for both Rocky Mountain spotted fever and tularemia. Rocky Mountain spotted fever causes fever, headache, and a characteristic spotted rash that often starts on the wrists and ankles. Tularemia can also be acquired through contact with infected animals or contaminated water, not just tick bites. Both are treatable with antibiotics but can become serious without prompt care.
How to Prevent Tick Bites
Prevention comes down to two strategies: keeping ticks off your skin and checking for them afterward.
For repellents applied to skin, DEET remains the most effective option. A 10% concentration provides roughly two hours of protection, while a 24% concentration extends that to about five hours. The CDC also recommends picaridin and oil of lemon eucalyptus as alternatives, though their protection duration is closer to what you’d get from 10% DEET. For children over two months old, concentrations up to 30% are considered safe. Don’t use DEET on infants under two months.
Permethrin is a separate product meant only for clothing, not skin. You spray it on pants, socks, boots, and gear and let it dry completely before wearing. Permethrin-treated clothing kills ticks on contact and remains effective through several washes. Combining permethrin-treated clothing with a skin repellent gives you the strongest protection available.
A few practical habits help too. Tuck pants into socks in tick-heavy areas (it looks ridiculous, it works). Stick to the center of trails when possible. Wear light-colored clothing so you can spot ticks before they reach skin. After spending time outdoors, do a full-body tick check, paying attention to the scalp, behind the ears, armpits, waistline, and behind the knees. Shower within two hours of coming indoors. Toss clothes in the dryer on high heat for 10 minutes to kill any ticks hitching a ride.
What to Do if You Find a Tick on You
Use fine-tipped tweezers to grasp the tick as close to your skin as possible. Pull straight up with steady, even pressure. Don’t twist, crush, or try to burn the tick off. Clean the bite area with rubbing alcohol or soap and water. Save the tick in a sealed bag or container with the date noted, in case you develop symptoms later and a healthcare provider wants to know what species bit you.
Not every tick bite leads to infection. Most don’t. But if you develop a fever, rash, headache, or flu-like symptoms in the days or weeks following a bite, that’s worth getting checked out quickly. For Lyme disease especially, early treatment is straightforward and highly effective, while delayed diagnosis makes things more complicated.