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It’s Lyme Disease Awareness Month

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It’s Lyme Disease Awareness Month

By Karen Miller

March is West Coast Lyme Disease Awareness Month. The rest of the country designates May – why are we different? Most importantly: Because California’s “tick season” is year-round. 

Adult ticks appear in the greatest numbers in December–February and nymphal (immature) ticks in April and May. A local advocacy group, Target Lyme, chose March because it is just before peak nymphal tick season when one must be most aware. Nymphal ticks are small (1 mm, about the size of a poppy seed) and easy to miss. Also, unlike other regions of the U.S., more nymphal ticks than adult ticks are infected with Borrelia, the bacteria that causes Lyme Disease.

Another reason to emphasize our regional difference is that California has a diverse environment. We have twelve different tick-borne diseases endemic to Northern California, and all but one occur here in Sonoma County. (Relapsing Fever occurs in the Sierras.) In the rest of the US, most regions only have a few recognized tick-borne diseases. We have far more (see list). All have been found in ticks either in Sonoma County or nearby. Relapsing Fever Group (from Borrelia miyamotoi) alone has not yet been diagnosed here: there was not a commercially available test for it until 2014.

How many ticks do we have? A recent study found a density of 330 nymphal ticks per mile of trail at Annadel State Park in Santa Rosa. That is quite high: it was the second highest density in the Peninsula and North Bay areas studied. 12% of the Annadel ticks had Borrelia – the two local species that are known to cause human disease. 

How high is your risk of infection? We know there are “hotspots” with 41% of ticks were infected with Borrelia. One place in Marin County had 30% of nymphs and 60% of adult ticks infected with Anaplasma. Most places aren’t nearly that high. Two studies were done on humans living in “high risk communities” in or near Sonoma County. Both found nearly 1 in 4 of the people studied had a tick-borne disease (of the four pathogens they were looking for). It appears the risk is growing, perhaps due to climate change or other factors driving loss of diversity.

You can lower your risk by learning how to avoid tick bites. Know that adult ticks are out in greatest numbers in December through Feburary. Recognize how tiny nymphal ticks are and know that they are out in greatest numbers in April and May. Nymphal ticks often hide in bark. Don’t sit on logs, don’t lean up against trees and take extra care when collecting firewood or clearing brush. Avoid squirrels and wood rats – the primary host reservoirs of Borreliae. 

Lizards, when fed upon by nymphal ticks, cleanse the tick of Borrelia which explains why fewer adult ticks are infected. This applies only to Borrelia, not to the other endemic diseases. Unfortunately, a high lizard population can support many more ticks, sometimes resulting in an overall increase in human risk. Don’t count on lizards to keep you safe.

The City of Santa Rosa has proclaimed March as West Coast Lyme Awareness Month, as has Healdsburg and hopefully Petaluma. As our contribution, Target Lyme is setting up information tables in March around the county. Please come by, inform yourselves, get a look at real (yes, dead!) ticks and get the latest information on tick bite prevention. Look for green ribbons heralding our presence. We will be in Healdsburg Plaza March 5 (though without ribbons, 10 AM to 3 PM), Railroad Square March 19th (10 AM to 3 PM), and Petaluma Farmer’s Market March 15 (10 AM to 1:30 PM).

  • Lyme Disease
  • Babesiosis  
  • Anaplasmosis 
  • Erlichiosis  
  • Rocky Mountain Spotted Fever  
  • Spotted Fever Group (a new rickettsia discovered recently in Lake County)  
  • Relapsing Fever Group
  • Q Fever
  • Tularemia
  • Colorado Tick Fever
  • Tick Paralysis
  • Relapsing Fever


Easy Ways to Prevent Tick Bites:  

  • Wear clothing treated with permethrin.
  • Use a repellant with DEET, picaridin or lemon oil of eucalyptus (a non-toxic choice) on your skin.  
  • Don’t sit on logs. 
  • Do frequent “tick checks”, particularly with children and dogs.  
  • Don’t bring ticks into the house: strip down and put your clothing in the dryer on high heat for 15 or 20 minutes.  
  • Shower right away.  
  • Don’t sleep with your dogs.


Karen Miller has provided a support group, Lyme Aid – Santa Rosa,  for tick-borne disease patients and their caregivers for 7 years. She is a patient herself.  She also was a founding member of the Tick Borne Diseases Advisory Group in concert with Marin/ Sonoma Mosquito and Vector Control District, Sonoma County Public Health, and California Department of Public Health.  She is currently lead advocate.  In addition, she is a founding member of Target Lyme, a group formed to advocate for patient rights and promote public education about all tick—borne diseases in Northern California.  Contact her at hbgkaren@sonic.net or (707) 843-0197.


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