New Lyme Disease Test
by Mary Jasch
Got an ailing gardening friend or relative who is positive she has Lyme disease but the tests come back negative or point to another disease whose treatment doesn’t work? If so, the answer may lie in either the test or the disease itself.
Now there is hope for those bitten by the blacklegged tick (aka deer tick) but who don’t display the tell-tale rash of Lyme disease. New tests that more accurately detect the presence of antibodies associated with the spirochete bacterium, Borrelia burgdorferi, only have been developed.
Louis A. Magnarelli, PhD, medical entomologist and director, Connecticut Agricultural Experiment Station in New Haven, whose research focuses on the immunology of Lyme disease and how people and other animals develop antibodies to the bacterium has contributed significantly to a test which involves using proteins specific to the bacterium.
“By studying the immunology of the responses of people and animals to the Lyme disease organism – once you know that, you can improve antibody tests,” says Magnarelli, who published in the Journal of Clinical Microbiology regarding his re-development of one of the first Lyme disease tests in the U.S. in 1984. The test, an enzyme-linked assay, was originally invented by British scientists before for testing other diseases. “My work has been focused on developing and improving antibody tests for Lyme disease.”
Antibodies are directed to specific proteins on the surface of the Lyme disease bacterium. When a person gets sick, the body produces antibodies to destroy the organism. The antibodies then bind to the outer surface of the bacterium and immobilize it and kill it.
The enzyme-linked assay in current use for preliminary screening consists of growing the spirochete in liquid cultures, separating by centrifuging the spirochetes out, and then busting up the spirochetes in a solution and distributing them across 96 wells in a plastic plate. To that, the human blood sample and reagents are added. After two hours, a reaction occurs.
“It worked good at first but there were some false positives associated with the test because other spirochetes, like the syphilis agent and others, have internal proteins that are shared with the Lyme disease organism,” says Magnarelli. A false negative can occur if the blood sample is taken too soon. Three weeks is usually sufficient time for antibodies to form a high-enough concentration.
If the enzyme-linked assay is positive, then the Western Blot Analysis is done for confirmation. The Blot is done on paper and with sufficient antibodies, it produces a series of bands.
“If you have the key bands against highly specific proteins for the organism that are not found on any other disease organism, then you have a positive confirmation of the enzyme-linked assay,” says Magnarelli.
The new method uses key proteins of the Lyme disease bacterium that are not found in any other disease organism, such as that which causes syphilis, in the plates of the enzyme-linked assay. Then, antibody reactions give a readout specific to Lyme disease.
“There are some key proteins that we have been testing here that have been produced at Yale University and University of Texas that have very good results. We’re seeing highly specific and highly sensitive test results. There have been great improvements in the technology for testing for antibodies against the Lyme disease organism. That’s all of my work.”
Sensitivity refers to the ability of the test to detect low concentrations of antibodies – or early production antibodies, say if the test was done soon after a tick bite. This new assay would replace current enzyme-linked assays and prevent cross-reaction of proteins.
A commercial test kit containing these specific proteins has been on the market for about five years. And veterinarians are using it a lot.
“I’m not sure if the very new technologies are being accepted by the medical profession. It certainly is by the veterinarians,” says Magnarelli. “I think there’s a lot of reluctance on the part of physicians to jump on the bandwagon for a new test. They want to see a track record for a new test and it takes time for them to come around to it.”
Magnarelli also studies different disease organisms in the northeast associated with the deer or black-legged tick: the spirochete bacterium that causes Lyme disease; Anaplasma phagocytophilum, a bacterium that causes Granulocytic Anaplasmosis; Babesia microti, a protozoan that causes human Babesiosis; and a possible virus that causes Powassan Virus, an Encephalitis virus that he has been working on for 1.5 years in collaboration with a scientist in New Mexico.
“It’s too soon to tell right now,” Magnarelli comments. “Some people who are ill – with a record of a blacklegged tick bite – have flu-like illnesses. When the antibiotics are given for Lyme disease, these people do not respond and get better. To me and others, that’s a clue that there could be something else out there that’s a virus because antibiotics are not effective against most viruses.”
Not to be outdone, the American dog tick is implicated in Rocky Mountain Spotted Fever. The culprit: Rickettsia rickettsii, a rickettsial agent which is killed by antibiotics.
Most abundant in May and June, the American dog tick lives in grassy areas and meadows and feeds on possum, raccoons, meadow voles, and chipmunks. It becomes infected by feeding on an infected host. That tick likes to align on grasses along the edge of a path through a meadow area in the open. As an adult, they then feed on a person to transmit the organism.
An infected female American dog tick will pass the pathogen to the next generation through its eggs, Magnarelli says. Female blacklegged ticks infected with the spirochete can pass it to the eggs but the disease organism becomes relatively non-pathogenic so the larval tick is not known to acquire a pathogenic strain of the Lyme disease organism that way.
The good news about the new Lyme disease test is that veterinarians are using it to quickly protect and diagnose your pets. The bad news is that only veterinarians are using it. So if you want a fast diagnosis, you may want to see your favorite vet.
Create a tick-resistant garden. See how here.
Deer tick life cycle & photos here.
Six labs that test deer ticks here.
Accepted Lyme Disease tests here.
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published December 17, 2010