Study: Lyme disease-infected ticks found in 'all kinds of habitats'


By Kate Daly | Special to the Almanac

A study funded by the Portola Valley-based nonprofit Bay Area Lyme Foundation found the bacteria that cause Lyme disease "in every place we looked" in this region, according to Executive Director Linda Giampa.

The Public Library of Science just released the results online. In May of 2013 researchers from Stanford and Northern Arizona universities led an effort to collect Western black-legged ticks, the tick that transmits Lyme to people on the West Coast.

They dragged flannel blankets on and around trails in 20 parks and open spaces extending from Sonoma to Santa Cruz counties, caught and then tested 349 nymphs and 273 adults.

Out of all the sites sampled Ms. Giampa said, Windy Hill Open Space Preserve had a "slightly, slightly higher percentage" of infected nymphs.

She hikes Windy Hill with her dog often and isn't all that worried about the threat of Lyme disease because, she said, compared to the East Coast, this study shows "overall it's a low percentage of ticks carrying the bacteria, about five out of every 100 nymphs."

The infected nymphs were found in the coast live oak woodland and Douglas fir parts of the preserve, whereas at nearby Thornewood Open Space Preserve, some infected nymphs turned up in coast live oak forest and then, to a lesser degree, in redwood forest.

Ms. Giampa said that's one of the surprising parts about the study, discovering that infected ticks exist in all kinds of different habitats.

Tick season is year-round in California, but since ticks like moisture, she said, the good news is "in a drought there are currently less ticks in the area than in the past."

Another surprise researchers found is that a strain of bacteria that has caused tick-borne relapsing fever on the East Coast and in Europe, has now moved into the Bay Area in increasing numbers.

On this coast, Western gray squirrels and dusky-footed wood rats are the most common carriers of the bacteria that cause Lyme disease. When a tick bites a host animal and then latches onto a person, the disease can be passed along. The longer the tick is attached to the person, the higher the chance of transmission.

Ms. Giampa encourages everyone to take preventative measures and be vigilant when outdoors. She suggests wearing protective clothing and checking for ticks periodically and thoroughly. Nymphs are particularly easy to miss because they are the size of a poppy seed.

Lyme disease can be treated with antibiotics. Without treatment, symptoms can develop over time and range from headaches to swollen joints and neurological problems.

"Anecdotally, we think (Lyme disease) does affect people differently, and, anecdotally, we think some people have an immunity to ticks," Ms. Giampa said, adding that the varying responses may have something to do with the genetically diverse variety of both the bacteria and people involved.

Right now, the Bay Area Lyme Foundation is supporting a study to find out why some people are "tick magnets." Another study is in the works to collect and compare ticks all over the country.

Visit for more information about the organization.

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5 people like this
Posted by Jeff Levy
a resident of another community
on Oct 9, 2015 at 2:01 pm

This information should help to make everyone aware of how important it is to prevent tick bites. What can be done includes dressing properly and proper use of repellents such as DEET permethrin, and some of the natural products. Information about prevention, diagnosis and treatment of Lyme disease and other tick-borne illness, based on current scientifically-validated peer-reviewed published research can be found at Web Link.

4 people like this
Posted by Think!
a resident of Menlo Park: Central Menlo Park
on Oct 9, 2015 at 6:35 pm

Our San Mateo County Mosquito and Vector Control District has known about this very Lyme/Ticks situation for years now and has been acting accordingly with their labs and personnel. Our towns each have a delegate who sits as a Trustee on that District Board and can be reached by phone or email. This is by no means new news.

4 people like this
Posted by Kristina
a resident of Menlo Park: Suburban Park/Lorelei Manor/Flood Park Triangle
on Oct 9, 2015 at 7:06 pm

And be aware that you don't have to go to a park or open space to get Lyme disease, I got it from either my home in the Flood Triangle or from walking on the streets of Lindenwood.

2 people like this
Posted by Another Tip
a resident of Atherton: West Atherton
on Oct 10, 2015 at 7:45 pm

Be aware that even if your dog wears a "flea and tick" collar that is capable of actually killing these pests, it requires longer to kill ticks so they have time to transmit Lyme Disease to their dog-victim before they die. Therefore, contact a veterinarian and have your dog vaccinated against Lyme Disease. The collar is not as protective as you think! Examining your dog's skin daily, especially on the feet and underside where hair is thinner, is essential to getting the ticks off before they can transmit the disease.

Like this comment
Posted by Ongine
a resident of Menlo Park: Linfield Oaks
on Oct 11, 2015 at 1:58 pm

I read another study that stated that ticks can become more prevalent in a drought, and more likely to attach to humans under these conditions. I've personally had more encounters with them hiking along the Arastradero Rd trails in Portola Valley, and along the Alpine Rd trails. I would be interested to hear if anyone with horses is having more trouble with them, so we can consult our vets and work together.

Like this comment
Posted by Entomologist
a resident of Menlo Park: Allied Arts/Stanford Park
on Oct 12, 2015 at 1:06 pm

Be aware that only a particular species of ticks can transmit the infective agent for Lyme Disease. Most ticks cannot. And there are other even more deadly diseases that certain types of ticks can transmit so Lyme is not the only concern. Beware that you needn't go out into the woods or countryside to acquire ticks. They are delivered to your home via a load of firewood or nursery plants. Bring the firewood into your house for storage and you've done the ticks a great favor.

Like this comment
Posted by Hmmm
a resident of another community
on Oct 12, 2015 at 2:10 pm

Ongine - after several encounters with ticks in the increasing drought, we quit spending so much time at the baylands on narrow trails. Since the drought started, we've avoided hiking the hills due to tick-borne diseases and coyotes. We have dogs and know too many whose dogs have suffered from tick-borne illnesses they've acquired in the hills. My friends who ride horses locally have taken extra precautions, and so have friends in Sonoma County.

Another precaution to take for dog owners is the leptospirosis vaccine because the drought is impacting rodent behavior.

Sorry, but further commenting on this topic has been closed.

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