Risk of Tick-borne Disease Transmission is Year-round in Marin & Sonoma Counties

Release date: 
Dec 20

Cotati, CA- Officials with the Marin/Sonoma Mosquito & Vector Control District (MSMVCD) are urging the public to take precautions against ticks when engaging in outdoor activities this winter. Adult Ixodes pacificus, the western black-legged tick (also known as the deer tick), are most active from fall through

early spring, while the tiny nymphs (juveniles) are most active in the spring and early summer. Both stages of ticks can transmit the bacterium that causes Lyme disease as well as other tick-borne diseases.

Piper Kimball, Scientific Programs Director for the MSMVCD, stated that most people associate tick season with spring, however ticks are present year-round.    

"Personal protection measures should be taken before, during, and after being in tick habitat, no matter what time of year it is," stated Ms. Kimball.   

Ticks can be found in grassy, brushy, or wooded areas, especially along sides of trails. Contrary to popular belief, ticks do not fly, jump, or fall out of trees. Adult ticks wait on the tips of vegetation with legs outstretched for people or other animal hosts to grasp onto, while nymphs are commonly found in leaf litter or on logs and branches. Research shows that the highest risk factors for coming in contact with nymphs are sitting on logs or leaning against trees, followed by walking or sitting in leaf litter.

After a tick grasps onto a host, it will crawl in search of a suitable location to attach to the skin. Generally speaking, the longer the tick stays attached, the higher the risk of disease transmission. The tick may remain attached for many hours or several days, after which it will drop off the host.

The MSMVCD's lab conducts tick surveillance and disease testing in various areas within Marin and Sonoma counties. Testing results indicate that an average of 3-5% percent of adult ticks collected are infected with the bacterium that causes Lyme disease.  

Protect yourself and your family against ticks: 

  • Wear light-colored clothing with long sleeves and long pants when hiking,   walking, or working in areas where ticks may be present.
  • Pre-treat clothing and equipment with permethrin to kill ticks.
  • Apply repellent containing DEET (at least 20% concentration) on exposed skin to repel ticks as well as mosquitoes.
  • Showering after being in tick habitat is one of the best ways to detect ticks. Continue to periodically check your body for several days after you have been in tick habitat.
  • Remove ticks promptly using the correct techniques.
  • Contact your physician if you have concerns or become ill after being bitten by a tick.