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Last updateThu, 23 Mar 2017 2pm

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Stanford study highlights threat of tick-borne disease in Bay Area


Western blacklegged tick

Better get that cootie shot: Disease-infected beasties are afoot, and they want your blood.

“It’s easy to remember: The bloodsuckers come out around Halloween,” said Denise Bonilla, Santa Clara County Vector Control District manager.

Bonilla is referring to adult Western blacklegged ticks, those ugly little parasites responsible for transmitting the bacterium that causes Lyme disease and the bacterium that causes tick-borne relapsing fever. On the East Coast, where Lyme disease was first recognized, ticks are a seasonal threat that dissipates when the arachnids hibernate in the winter. But in California, Florida and Texas, where the weather remains comparatively warm, ticks are active year-round. Adult ticks seek hosts from late fall to spring. Immature nymphal ticks, smaller than adults and more likely to carry disease pathogens, abound from spring to mid-summer.

Out for blood

Bay Area Lyme Foundation, a Portola Valley-based nonprofit organization, recently sponsored a joint Stanford University-Northern Arizona University study documenting diversity among bacterial species and strains that cause tick-borne illness. The results, reported last month in a Public Library of Science scientific journal, suggest that tick-borne pathogens are prevalent across the Bay Area, including at Santa Clara County parks.

Study contributor Dan Salkeld is a Colorado State University disease ecologist formerly with the Stanford Woods Institute for the Environment.

“We continue to be surprised by the number of ticks carrying (bacteria) throughout the Bay Area, and believe more research into the connections between human disease and strains and species of bacteria is critical,” Salkeld said in a statement issued by the foundation.

Between May 2012 and May 2013, researchers collected Western blacklegged nymphal ticks from 20 Bay Area locations, including Foothills Park and Hidden Villa Park of Los Altos Hills. Of the collection sites, Windy Hill Open Space Preserve in Portola Valley ranked highest for infection, but there wasn’t a significant difference between “first and second place,” said Linda Giampa, Bay Area Lyme Foundation executive director.

Foothills Park ranked fourth among sites, but Hidden Villa was “low on the chart,” Giampa said.

Study results indicate that the rate of tick-borne relapsing fever-infected ticks is higher in the Bay Area than rates documented on the East Coast. Redwood trees, once dismissed as poor habitats for disease-causing ticks, were shown to harbor infected ticks. Also troubling was the detection of a variety of strains that cause Lyme disease, a potential explanation for why symptoms vary among Bay Area patients.

‘The Great Imitator’

The Santa Clara County Vector Control District wasn’t involved with the study – the office conducts its own tick surveillance – but Bonilla is familiar with the results.

“They used to call syphilis ‘The Great Imitator,’” she said. “Now they call Lyme disease ‘The Great Imitator’ because there’s such a wide range of symptoms you can get.”

If detected early, Lyme disease can be treated with antibiotics such as doxycycline, but diagnostic tests are unreliable and the infection is often misdiagnosed because symptoms such as headache and fatigue mimic flu symptoms; a telltale bull’s-eye rash is not always present.

After several weeks, the infection progresses into chronic Lyme, a condition that can cause severe joint pain, chronic fatigue, neurological problems and other symptoms that persist throughout the remainder of a patient’s life. A Lyme disease vaccine for humans does not currently exist, but several scientific trials are underway in Europe.

That’s why it’s important for Bay Area residents and visitors – particularly those who frequently play and work outside – to practice vigilance, Giampa said.

“If you miss that opportunity, and you go undiagnosed, you have a big chance of getting chronic Lyme,” she said.

To prevent Lyme disease and other tick-borne illnesses, experts advise outdoor enthusiasts like hikers, campers and green thumbs to wear protective clothing and repellents and to check for ticks afterward. They recommend removing clothing and showering within two hours of returning inside, as extracting a tick within 24 hours greatly reduces the chances of developing Lyme disease. Dogs and cats allowed outside, even those on tick-control products, should be examined as well, because ticks die only after biting medicated pets and can fall off fur or become dislodged before doing so.

“We just want to get the word out to stop as many people from getting this terrible disease as possible,” Giampa said.

Research for a cure

Mike Neal well knows the debilitating nature of chronic Lyme disease. The Santa Clara County Fire Department captain’s wife contracted Lyme 15 years ago while out for a walk near their Santa Cruz Mountains home and has suffered from horrendous flu-like symptoms, chronic pain and insomnia ever since. Doctor after doctor misdiagnosed Elizabeth Neal; infuriatingly, one spinal expert believed that her pain was psychosomatic and suggested she try antidepressants.

Elizabeth Neal, now 55, has become a vocal advocate for Lyme disease research, but grappling with excruciating pain, experimental treatments and antibiotics administered both orally and intravenously have transformed her from an active, vivacious woman into a recluse, her husband said.

“Her life has been ripped from her completely,” Mike Neal said.

Neal said the Bay Area Lyme Foundation study has validated the Lyme community’s push for better treatments, vaccines and research for a cure.

“There’s a lot of arrogance and ignorance about Lyme in the medical community, but they’re beginning to realize it’s endemic,” he said.

To read the Lyme Foundation study “Disease Risk & Landscape Attributes of Tick-Borne Borrelia Pathogens in the San Francisco Bay Area, California,” visit bit.ly/1HXRwvm.

For more information on the Bay Area Lyme Foundation, visit bayarealyme.org.

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