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 bayarealyme.org for more information about the organization.