Now that warmer weather is upon us, outdoor enthusiasts have to grapple with tick season. Ticks are well known for spreading a number of zoonotic diseases (or diseases that can be transmitted from humans to animals), namely Lyme disease. However, California is armed with an unlikely defense against the spread of Lyme disease: western fence lizards.
Ticks and Lyme Disease
The most common tick found in the Yuba Watershed is the western blacklegged tick, Ixodes pacificus. Western blacklegged ticks are found in differing habitats depending on their life stage. Nymphs inhabit dense woodlands with abundant leaf litter, while adults are frequently found in areas with shorter vegetation, such as grasslands. Adult ticks seek out hosts by climbing a plant and waiting for a host to brush against the plant. The tick then crawls onto the host to find an appropriate feeding site before latching on. Typical hosts for ticks include small mammals, birds, lizards, and deer, although they will feed on humans and domestic pets if given the opportunity.
Like their eastern sister species, western blacklegged ticks are transmission vectors for Borrelia burgdorferi, the bacteria that causes Lyme disease. Ticks do not inherently carry this bacteria. Instead, they acquire it by biting an animal that is infected with Lyme disease. The tick can then transfer the bacteria to the next host animal it feeds on. Early symptoms of Lyme disease include a bullseye rash, fever, headache, and fatigue. If left untreated, symptoms can progress to include facial nerve paralysis, joint pain, and heart palpitations, among other symptoms.
Western Fence Lizards
Western fence lizards (Sceloporus occidentalis) are the most ubiquitous lizard species in much of California. Colloquially referred to as “blue bellies”, western fence lizards can be identified by darker, keeled scales on their backs and legs and bright blue markings on the sides of abdomen. They are easily found in open, sunny areas, basking on rocks or other warm surfaces.
While most people do not think much of the lizard they see everyday on their porch, western fence lizards play an extremely important part in disease control. As nymphs, western blacklegged ticks preferentially seek out western fence lizards to feed on. With most host species, a tick containing Lyme disease causing bacteria would infect the host within 24 hours of biting them. However, in 1998, scientists found that western fence lizard blood contains a protein that kills the B. burgdorferi bacteria. Not only does the lizard not become infected with the bacteria, but the tick is also cured of the infection!
This superpower is thought to help decrease the incidence of Lyme disease across California. Despite this, recent studies have shown that removing western fence lizards from the environment dramatically reduces the amount of ticks carrying Lyme disease. Leading researcher Dr. Andrea Swei hypothesizes that the reduction of the young ticks’ favorite hosts means that not enough are surviving to adulthood to continue the cycle of Lyme disease.
These findings show that we still have a lot to learn about how the ecology of Lyme disease in California.
How to Protect Yourself from Ticks
Although having western fence lizards around can help decrease your chances of catching Lyme disease from a tick bite, there are other diseases that ticks can transmit. Here are some tips from the CDC on how to stay safe in the middle of tick season.
- Avoid walking through areas with tall grass or abundant leaf litter.
- Use 0.5% permethrin on clothing and EPA approved insect repellent on skin.
- After coming indoors, examine all clothing and gear for ticks.
- Shower within 2 hours of coming indoors to do a more thorough tick check.
- If a tick attaches to you, carefully remove it and all mouthparts with fine-tipped tweezers as soon as you notice it.
- Talk to your veterinarian to find a tick-preventative that works effectively for your pets.
- If your pets have been roaming through tick habitat, make sure to conduct a thorough tick check on their bodies after bringing them indoors.
- Remove any ticks promptly.
- Keep grass and brush around the house well-groomed.
- Stack wood away from the home.
- Create a 3-foot barrier of gravel or mulch between brush and recreational areas.
- Remove all large trash that could give ticks a place to hide.