Ticks are present across the Pacific Northwest (PNW), a region encompassing Oregon, Washington, and parts of British Columbia. While tick-borne illness often centers on the Northeastern United States, the PNW hosts its own distinct and medically significant tick population. These parasitic arachnids thrive in the region’s diverse ecosystems and represent a public health concern for residents and visitors engaging in outdoor activities. Understanding the specific species, their environments, and the diseases they transmit is the first step in mitigating the risk.
Common Tick Species and Their Habitat
The most common tick species in the PNW is the Western Blacklegged Tick (Ixodes pacificus). This dark, brownish-black tick is primarily found along the Pacific Coast, spanning western Washington and Oregon. It typically inhabits forested areas, coastal scrub, and brushy edges of woodlands. In milder climates, adults are often active year-round, typically from October through May.
Another prominent species is the Rocky Mountain Wood Tick (Dermacentor andersoni). This reddish-brown tick is more prevalent in the eastern, high-elevation areas of Washington and Oregon. It is generally encountered in mixed grassland and forest habitats, often between 4,000 and 10,500 feet. Unlike the coastal species, the Rocky Mountain Wood Tick is most active during the spring and early summer, with peak activity occurring from March through July. Both species wait on low-lying vegetation for a host to pass by, a behavior known as questing.
Disease Transmission and Regional Risk Factors
The primary health concern associated with Ixodes pacificus is Lyme disease transmission. Although this tick is the vector in the PNW, the rate of transmission is low compared to the Northeast US, which reports 30 to 80 cases per 100,000 people annually. The Pacific Coast incidence is closer to 0.2 cases per 100,000 persons, and locally acquired cases in Washington State are rare. This lower rate is partly due to the Western Fence Lizard, a common host for immature ticks, which clears the Lyme-causing bacteria from the tick’s system.
Ixodes pacificus can also transmit the pathogen responsible for Anaplasmosis, a bacterial infection causing flu-like symptoms. The Rocky Mountain Wood Tick (Dermacentor andersoni) spreads several other diseases, including Rocky Mountain Spotted Fever (RMSF), Colorado Tick Fever, and Tularemia. RMSF is considered a more common outcome of a tick bite in the western states than Lyme disease. The risk of infection remains very low if the tick is removed within 24 hours, as attachment must generally last for a specific duration for transmission to occur.
Essential Steps for Prevention and Removal
Protecting yourself from tick bites begins with preparation before entering tick habitats. When hiking in tall grasses or brush, wear light-colored clothing to spot ticks easily and tuck pants into socks to create a physical barrier. Apply an EPA-registered repellent containing DEET (30% or less concentration) to exposed skin and clothing. Permethrin-treated clothing provides additional protection, especially during extended time in known tick areas.
After returning indoors, perform a thorough tick check on yourself, children, and pets. Ticks often migrate to warm, hidden areas like the groin, armpits, and scalp. Prompt and proper removal of an attached tick is the most effective way to reduce the risk of infection.
To remove an attached tick, use clean, fine-tipped tweezers to grasp the tick as close to the skin’s surface as possible. Pull upward with steady, even pressure, avoiding twisting or jerking the tick, which could cause the mouthparts to break off. After removal, thoroughly clean the bite area and your hands with rubbing alcohol or soap and water. Never use folklore remedies like petroleum jelly, nail polish, or heat, as these methods can agitate the tick and increase the risk of disease transmission.