Yes, ticks are well established in San Diego County. The region’s mix of chaparral, coastal sage scrub, and canyon trails creates ideal habitat for several tick species, some of which carry disease-causing bacteria. Whether you’re hiking in the backcountry near Cuyamaca or walking through a suburban canyon in Scripps Ranch, tick encounters are a real possibility, especially during the cooler, wetter months.
Which Tick Species Live in San Diego
California is home to 48 established tick species, and two are particularly relevant for San Diego residents. The western blacklegged tick is the most widespread and abundant tick in the state, reported in 56 of California’s 58 counties. It’s the only species that transmits the bacterium responsible for Lyme disease to humans, and both its nymphal (immature) and adult female stages can bite and infect people. Nymphs are roughly the size of a poppy seed, making them easy to miss on your skin.
The Pacific Coast tick is the other species you’re likely to encounter in San Diego. It’s the sole known carrier of a bacterium called Rickettsia philipii, which causes Pacific Coast tick fever. Six tick species in California regularly attach to humans, and these two are the ones most worth knowing about in the San Diego area.
Where Ticks Are Found Locally
Ticks thrive in grassy, brushy areas and on the plants that line trails. In San Diego County, that means the chaparral-covered hillsides, coastal sage scrub, and riparian corridors that run through much of the region. You don’t need to be deep in the wilderness to encounter them. Suburban canyon trails, nature preserves near residential neighborhoods, and even the grassy edges of park paths can harbor ticks.
Areas like the Elliott Chaparral Reserve near Scripps Ranch, with its mix of chamise chaparral, coastal sage scrub, and narrow creek corridors, are textbook tick habitat. The San Diego County Department of Environmental Health has collected and tested ticks from diverse locations across the county, including Sorrento Valley, Escondido, and the Cuyamaca Mountains. In short, ticks aren’t limited to one corner of the county. They’re present from the coast to the mountains.
Tick-Borne Diseases in San Diego County
Ticks in San Diego carry real pathogens. In 2012, nineteen county residents were diagnosed with confirmed or probable tick-borne illnesses: fourteen cases of Lyme disease, two of Rocky Mountain spotted fever, two of other rickettsial diseases, and one case of ehrlichiosis. Those numbers reflect reported cases only, and mild or misdiagnosed infections likely push the true count higher.
Testing by the county’s Department of Environmental Health found spotted fever group Rickettsia in 10 to 20 percent of tick batches collected locally. That’s a meaningful infection rate, and it includes Rickettsia philipii, the bacterium behind Pacific Coast tick fever. First reported in Northern California in 2008, this pathogen has since been detected in tick batches from Sorrento Valley, Escondido, and the Cuyamaca Mountains. A bite from an infected tick can cause a distinctive black scab of dead skin at the bite site, along with fever, headache, and fatigue.
Lyme disease remains the most well-known risk. It’s caused by the bacterium Borrelia burgdorferi, transmitted exclusively by the western blacklegged tick. Early symptoms typically include a spreading rash, fever, and joint pain, and the illness can become chronic if untreated. The good news: removing a tick within 24 hours dramatically reduces your chances of contracting Lyme disease, because the bacterium needs time to transfer from the tick’s gut to your bloodstream.
When Tick Activity Peaks
Adult ticks in Southern California are most active during the cooler, wetter months, roughly November through May. This coincides with San Diego’s rainy season, when grasses and brush grow taller and the humidity ticks need to survive is more abundant. Nymphs, the tiny immature stage most likely to go unnoticed on your body, tend to be active in spring and early summer. Because San Diego’s climate stays mild year-round, tick encounters can happen in any month, but the risk drops noticeably during the hot, dry summer and early fall.
How to Protect Yourself
Staying on established paths and trails is the simplest way to reduce your risk. Ticks don’t jump or fly. They wait on the tips of grasses and low brush, latching onto anything that brushes past. Walking through the center of a cleared trail rather than pushing through vegetation on the edges makes a real difference.
Clothing matters. Long sleeves and long pants create a physical barrier, and light-colored fabrics make it easier to spot ticks crawling on you before they reach skin. Tucking pants into socks looks silly but works. For chemical protection, the EPA registers several effective repellents: those containing DEET, picaridin, IR3535, or oil of lemon eucalyptus can be applied to both clothing and exposed skin. Permethrin-treated clothing is another option for frequent hikers.
After any time in brushy or grassy areas, do a thorough tick check on yourself, your hiking companions, and your pets. Pay close attention to warm, hidden spots: behind the ears, along the hairline, in the armpits, behind the knees, and around the waistband. Keep pets on leash and on-trail while hiking, since dogs that wander into brush are excellent at picking up ticks and carrying them home.
How to Remove a Tick Safely
If you find a tick attached to your skin, use fine-tipped tweezers to grasp it as close to the skin surface as possible. Pull upward with steady, even pressure. Don’t twist, jerk, or squeeze the tick’s body, as that can break off the mouthparts or push infected fluids into the bite. After removal, clean the bite area with rubbing alcohol or soap and water. Save the tick in a sealed bag or container if you want it identified or tested later.
Speed matters more than technique. Removing a tick within the first 24 hours greatly reduces the chance of Lyme disease transmission. Because nymphs are so small, many people never notice the bite, which is why the post-hike body check is more important than any repellent you apply beforehand.