Tick Surveillance


  • The District collects western black-legged ticks (Ixodes pacificus) to test for the presence of Borrelia burgdorferi, the bacterium that causes Lyme disease, and Dermacentor spp. for collaborative research efforts.

Collecting ticks:

  • District staff collect ticks at various parks and other publicly owned lands in Marin and Sonoma counties by a method called flagging. Ticks are sorted by species, gender and collection location, and are frozen until they are tested. 

 Testing ticks:

  • Western black-legged ticks (I. pacificus) are tested for the presence of B. burgdorferi DNA using Real-Time PCR technology.  
  • In 2009, District lab staff conducted research on using Real-Time PCR for testing ticks for B. burgdorferi. The research resulted in a poster that was presented at two professional conferences and a paper that was published in the 2010 Mosquito & Vector Control Association of California Proceedings and Papers.  
  • In 2012, the overall minimum infection rate (MIR) in I. pacificus adults for Marin and Sonoma counties was 2.3% and 3.0% respectively. The overall minimum infection rate (MIR) in I. pacificus nymphs for Marin and Sonoma countieswas 3.9% and 4.7% respectively.
    • Click here for a summary of results for 2012
    • Click here for a summary of results for 2013
    • Click here for 2008-2016 summary results
    • Click here for 2015 Tick Surveillance Report
    • Click here for 2016 Tick Surveillance Report
    • Click here for 2017 Tick Surveillance Report
    • Click here for 2018 Vector Surveillance Report
  • The District collaborates with other agencies and educational institutions on various research projects related to ticks and tick-borne disease. In 2010 the District collaborated on a poster with Humboldt State University on the prevalence, density, and geographic distribution of two novel Rickettsia species in I. pacificus.

Useful links:

Clickable Link / Format Document Title
Paper (PDF)
  • Using Real-Time PCR to Detect Borrelia burgdorferi Infection in Ixodes pacificus
 Poster (PDF)
  • Using Real-Time PCR to detect Borrelia burgdorferi infection in Ixodes pacificus
Graph (PDF)
  • 2011 Minimum Infection Rates of Ixodes pacificus with Borrelia burgdorferi in Marin and Sonoma Counties
Poster (PDF)
  • Prevalence, Density, and Geographic Distribution of Two Novel Rickettsia Species in Ixodes pacificus from California by real-time PCR