Ticks are a reality of the outdoor landscape in Los Angeles County and across Southern California, contrary to a common belief that they are only a concern in other regions. Local tick populations carry and transmit several pathogens that can affect human health. Understanding the specific species, their preferred habitats, and the diseases they transmit is important for minimizing exposure when enjoying the region’s diverse natural areas.
Common Tick Species in Southern California
The most medically significant species in Los Angeles County is the Western Black-legged Tick, Ixodes pacificus, the primary vector for Lyme disease in the western United States. The adult female is small, measuring about 2.6 millimeters, identifiable by its black legs and dorsal shield contrasting with a reddish-brown abdomen. The Pacific Coast Tick, Dermacentor occidentalis, is larger, widespread throughout the state, and has a mottled, dark brown body with whitish-gray markings. The Brown Dog Tick, Rhipicephalus sanguineus, is also present. Although primarily an indoor pest of dogs, local health data indicates it will feed on humans in the county.
Local Habitats and Risk Areas
Ticks in Los Angeles County thrive in specific environments popular for recreation, not just remote wilderness. High-risk areas include the chaparral and wooded canyons of the Santa Monica Mountains, such as Paramount Ranch and Malibu Creek State Park. Ticks favor cool, moist environments, waiting on the tips of low-lying vegetation like tall grasses and brush to latch onto a passing host. They quest for a host and do not jump or fly. The peak activity period for the Western Black-legged Tick runs from late November through May.
Health Risks Transmitted by Ticks
The most well-known concern is Lyme disease, caused by the bacterium Borrelia burgdorferi and transmitted by the Western Black-legged Tick. The local risk of acquiring Lyme disease is low, with only about 1 to 2 percent of adult I. pacificus ticks in the Santa Monica Mountains testing positive. Early symptoms often include a flu-like illness with fever, headache, and muscle aches occurring days to weeks after a bite. In 60 to 90 percent of cases, an expanding, circular rash known as Erythema Migrans may appear at the bite site, though its absence does not rule out infection.
The Pacific Coast Tick can transmit several other diseases, including Pacific Coast Tick Fever (caused by a Rickettsia species), Anaplasmosis, and Rocky Mountain Spotted Fever. Pacific Coast Tick Fever symptoms include fever, rash, and headache. Early diagnosis and antibiotic treatment are important for all tick-borne illnesses to prevent progression to more severe complications affecting the joints, nervous system, or heart. If a bite is suspected or symptoms develop, seek medical attention.
Prevention and Safe Removal
Adopting protective measures before entering wooded or grassy areas significantly reduces the chance of a tick bite. Wearing light-colored clothing makes ticks easier to spot, and tucking pants into socks creates a barrier against questing ticks. Applying an EPA-registered insect repellent containing DEET to exposed skin or using products with Permethrin on clothing are effective chemical deterrents. Perform a thorough “tick check” of the entire body and clothing immediately after spending time outdoors.
If an attached tick is found, remove it safely. Disease transmission typically requires the tick to be attached for at least 24 hours. Use fine-tipped tweezers to grasp the tick as close to the skin’s surface as possible, ideally around the mouthparts. Pull upward with steady, even pressure without twisting or jerking, which can cause the mouthparts to break off in the skin. Avoid using folk remedies like petroleum jelly, nail polish, or heat, as irritating the tick may cause it to regurgitate infectious fluids into the bite wound.