Lizards For Chronic Lyme Disease
An epidemiologist who used to work at the State’s Health Department, Robert Murray, reported that the percentage of infected deer ticks in high Lyme disease areas such as Connecticut is 30 to 60 percent. But the percentage of black-legged ticks — the closely related cousins that carry Lyme disease in California — is only 1 to 2 percent, and only as high as 6 percent in areas such as Mendocino county, where the most Lyme disease cases are found.
According to California’s recent data, in California, only about one in every 200,000 persons is infected with Lyme disease as compared to Connecticut - the epicenter of Lyme disease the rate is 100 times higher. Unofficially we can only guess, but the recorded numbers at the National Center for Disease Control are admittedly only 10% of the actual numbers. But still one would suspect that the differences would be uniformly off.
In 1998, Sabin Russell, a reporter for the San Fransisco Chronicle wrote a provocative article with what appears to be hard evidence as to why the rate of Lyme disease occurrence grows less rapidly in California, and not by just a little bit.
As far back as the 1990’s researchers suspected that a yet- to-be-identified protein in the lizard’s blood destroys the microbes that would otherwise flourish in the tick’s belly (and is later transmitted to human victims.)
“We’ve speculated on this for years, and now we have fairly good evidence that this is the case,” said Robert Lane, a University of California at Berkeley insect biologist who has been studying ticks and Lyme disease for more than a decade.
Lane and his colleague Gary Quistad conducted a series of laboratory experiments using young Lyme disease-infected ticks and fence lizards.
In the nymphal stage during which they feed on the blood of lizards, the ticks are only about the size of a poppy seed. But it is common to find 30 to 40 at one time sharing the blood of a single fence lizard.
Lane discovered that a substance found in the blood of the common western fence lizard kills Lyme disease bacteria in the gut of juvenile ticks that feed on it. It may help explain why there is far less Lyme disease in California than in the eastern United States, where the lizard does not live.
The western fence lizard — a commonly found species dubbed the blue belly lizard in California - can carry an average of 30 juvenile black legged ticks, which are about the size of a poppy seed. Three stages of tick development Larval Ticks pass through three stages of development. During each stage they eat one “blood meal.” ‘ Larval ticks become infected with Lyme disease when they feed on rodents.
Lane had determined eight years ago that the lizards appeared to be immune to Lyme disease despite infestation with tick nymphs. His latest research, published recently in the Journal of Parasitology, suggest why this happens.
Berkeley’s Tilden Park served as the field laboratory for Lane, where he previously also uncovered a curious quirk about Lyme disease and the black-legged ticks that carry it there: the infection rates for young ticks, while low, was three to four times higher than the rate in adult ticks.
Early experiments ruled out the possibility that antibodies produced by the lizard’s immune system were able to neutralize the Lyme disease bacteria.
The puzzle continued to interest Lane who found later that when young nymphal ticks feed on the fence lizards, the mysterious protein not only protects the lizard from infection — it actually leaches into the tick’s gut and kills the bacteria there. Additional lab tests showed that when infected nymphs fed on the lizards, and then metamorphosed into adult ticks, they were no longer infected.
Test tube experiments found that Lyme disease bacteria bathed in lizard’s blood died within one hour, while control samples grown in mouse blood lasted three days.
In another experiment, the researchers heated lizard blood to the boiling point, and found that it no longer killed the bacteria in a test tube. The sum of these tests points to what Lane calls a “spirochete-killing factor” that is probably a large protein.
“It’s an extremely important paper,” said Vicky Kramer, chief of the vector-borne disease section of the California Department of Health Services.
Researchers are now trying to determine the precise nature of the Lyme disease-killing protein, and perhaps find out if it can be used to create a treatment for the disease.
Today, a decade later, Robert Lane has earned his PhD, and is a professor at U.C. Berkeley in the Department of Environmental Science, Policy and Management and supervises several projects aimed at expanding our knowledge of the relationship of various isolates of LD spirochetes (and other emerging tick-borne disease agents in the bacterial genera (Anaplasma, Bartonella, Borrelia, and Ehrlichia) to their vectors and hosts.
Spirochetes isolated from ticks and wildlife are being characterized antigenically and genetically, and the infectivity of selected isolates for vertebrates and ticks evaluated.
The ability of human and nonhuman-biting ticks to acquire, maintain and transmit the LD spirochete, and the role of lizards, birds and mammals in perpetuating it have been and still are being assessed both experimentally and in the field. Intrinsic and extrinsic factors that contribute to the vector efficiency of different ticks and to the reservoir competence of mammals also are being studied.
Another current focus of Dr. Lane’s research program is to determine the factors that elevate the risk of human exposure to ticks in endemic areas of northern California, particularly in dense woodlands and mixed hardwood forests.
According to the University, these studies are being conducted in wild land and recreational areas, and in some domestic settings in both rural and semi-rural communities endemic for LD.
It is anticipated that these investigations will clarify various ecological and epidemiological factors that place humans at heightened risk of exposure to the LDS and other emerging tick-borne infections at different spatial scales, and enable us to develop predictive models to assess LD risk at both the county and state levels by means of remote sensing and ground-truthing ecological studies.
Dr. Lane explains the ultimate goal of this research to use the basic knowledge gleaned from the previous and ongoing projects to develop and implement strategies for reducing human exposure to tick-borne disease agents.
The frustrating part of all this research is the incredible length of time it takes to go from one theory to a finished product that can help us now.
The exciting part of Dr. Lane’s research is that his focus is centered on using several host-targeted methods for disseminating environmentally safe pesticides to rodent reservoir hosts (such as the lizard) of the LD spirochete that have already have been assessed.
Lets hope we don’t have to wait another decade for this brilliant scientist to deliver the goods from his promising research.
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Thanks for visiting again - Please comment on the posts you read - everyone is interested in what you have to say.
November 16th, 2009 at 11:23 pm
OK, i will wait for the good news.
November 26th, 2009 at 4:18 am
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December 3rd, 2009 at 1:44 pm
There is no reason to doubt the statistics of borrelia prevalence. As you stated, there are plausible explanations for the difference between west and east coast. The message people on the west coast are missing is that 1-2% infection rate among ticks is still dangerous - even more so because doctors/citizens ignore the threat like it doesn’t exist. But it does.
December 4th, 2009 at 4:31 pm
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Cheers
December 24th, 2009 at 11:19 am
Really?!! I read about Dr. Lane’s research from nearly 12 years ago, and from what he learned, he is trying to save the LIZARDS?!! Noble, but how about a cure for PEOPLE?!!
Do I have to go catch a lizard myself?!