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Emerging Infectious Diseases journal reports “surprising” findings of ticks carrying B. burgdorferi and B. miyamotoi

Portola Valley, CA – Bay Area Lyme Foundation announced today that a new study funded by the organization will be published in the March issue of Emerging Infectious Diseases, a peer-review journal of the Centers for Disease Control and Prevention (CDC).  The study, which was conducted by researchers at the Stanford Woods Institute for the Environment and Northern Arizona University, indicates that ticks carrying Borrelia burgdorferi, (B. burgdorferi) the bacteria that cause Lyme disease, are widespread in the San Francisco Bay Area.

“We found ticks carrying B. burgdorferi in nearly every park that we looked – and not just in wooded areas. They were in the grassland and chaparral too,” said Daniel Salkeld, PhD, a Disease Ecologist at the Stanford Woods Institute for the Environment and one of the study’s authors.

Researchers looked at 12 recreational areas in the Bay Area and at every location found ticks carrying Borrelia, the genera of bacteria, which includes B. burgdorferi. Rates of infection for Borrelia ranged from about 1% – 7% and as high as 2.2 % for B. burgdorferi. While this incidence is low compared to east coast levels, it confirms the presence of these bacteria in Bay Area ticks.

“These findings are an important step toward dispelling the perception that you cannot acquire Lyme disease in northern California,” said Ana Thompson, Executive Director of Bay Area Lyme Foundation which funded the study. “We are concerned that many people don’t check for ticks or get treatment soon enough because they don’t believe they can be infected here,” continues Ms. Thompson.

“It was surprising to find ticks carrying Borrelia, in so many places. And, particularly unexpected was the prevalence of the disease-causing pathogen, B. miyamotoi,” continued Dr. Salkeld.

While there are no official reports of people in the Bay Area suffering from B. miyamotoi infections, study authors note that is it possible that B. miyamotoi infections could be misdiagnosed, and they advocate for greater research.

It was only 2011 when a study in the Emerging Infectious Diseases journal confirmed that B. miyamotoi can be transmitted to humans, reporting 46 cases of infection from B. miyamotoi in Russia. Then in 2013, cases of B. miyamotoi infection were uncovered at primary medical care centers in Massachusetts and New Jersey. Symptoms of B. miyamotoi infection include fever, headache, and muscle aches and is a close relative of the causative agent of tick-borne relapsing fever, B. hermsii, which is also found in California.

“My hope is this study will help the medical community in California develop a proactive stance on the diagnosis, assessment and treatment of a person suffering from early or late stage Lyme disease,” said Kathleen O’Rourke, who helped found Bay Area Lyme Foundation after contracting Lyme disease from a tick in her own backyard in Woodside.

About Lyme Disease

Lyme disease is a potentially debilitating infection caused by bacteria transmitted through the bite of an infected tick to people and pets. If caught early, most cases of Lyme disease can be treated, but it is commonly misdiagnosed due to lack of awareness and unreliable diagnostic tests. According to statistics released in 2013 by the CDC, there are about 300,000 new cases of Lyme disease each year, 10 times than previously reported. As a result of the difficulty in diagnosing and treating Lyme disease, at least 440,000 Americans suffer from the impact of its debilitating long-term symptoms and complications, according to Bay Area Lyme Foundation estimates. The real figure may be closer to 1 million.

While Lyme disease has been reported in every state except Hawaii, there are important differences between Lyme disease on the West coast and East coast. In California, the tick season is year round due to its temperate climate, whereas in New England and the mid-Atlantic, the tick season peaks in the summer months. Additionally, throughout the West coast, the tick that transmits Lyme disease is the Western blacklegged tick (Ixodes pacificus); in the East coast, and mid-Western states, it is the Eastern blacklegged tick (Ixodes scapularis). Of the many animal reservoirs which transmit the Lyme bacteria to ticks, the primary culprit in California is the grey squirrel, whereas, on the east coast, the white footed mouse is the more likely to transmit the bacteria to ticks.

About Bay Area Lyme Foundation

Bay Area Lyme Foundation is committed to making Lyme disease easy to diagnose and simple to cure.  A national 501(c)3 non-profit organization, the Foundation collaborates with world-class scientists and institutions to accelerate medical breakthroughs for Lyme disease. It is also dedicated to providing reliable, fact-based information so that prevention and the importance of early treatment is common knowledge.   For more information on Lyme disease or to get involved, visit or call us, 650-530-2439.



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