By Garret Condon, Courant Staff Writer
One of the thorniest issues in the treatment of Lyme disease has been figuring out who has it. A new high-tech test may help provide a better answer to anxious patients and their doctors.
“We’re all very much interested in a better test,” said Martin Schriefer, a research microbiologist with the federal Centers for Disease Control and Prevention. “It’s been controversial from the get-go.”
Who has Lyme and who doesn’t has been a hot topic among patients, advocates, researchers and physicians. While most cases of Lyme disease are easily diagnosed and treated, questions persist about how much Lyme disease is missed and how many cases of other illnesses are misidentified
– and mistreated – as Lyme.
Federal guidelines make it clear that Lyme disease is diagnosed primarily from symptoms and an assessment of the patient’s risk for the illness. A two-test procedure then has been used to support the diagnosis, but its uncertain accuracy has been an issue.
The first test screens blood for evidence of Lyme infection, but it’s not very specific. It detects antibodies to the microbe that causes Lyme, but many of the same antibodies are produced in response to other infections. If this test is positive, a second test, called a Western Blot, follows. While it is much more specific, it is also complicated and expensive and yields results that can be tough to interpret. It’s not 100 percent accurate.
In addition, the presence of antibodies doesn’t necessarily mean that a patient has an active infection, since the antibodies may hang around in the blood long after the infection itself is over. A further complication involves patients inoculated with the discontinued Lymerix vaccine. Many will get positive blood tests whether they have Lyme or not.
For years, researchers have been looking for better tests. Capturing and growing the actual bacterium is difficult, and although fragments of the microbe’s signature DNA sometimes can be found and replicated, this method has not yet yielded a standardized test. So a lot of lab time has gone into making antibody tests more accurate by finding target molecules that are specific to the Lyme-causing microbe.
In 1999, a team at Tulane University published the first article on the C6 peptide, a fragment of a surface protein found on the bacterium that causes Lyme. It appears to react only with antibodies produced during an active Lyme infection.
“The advantage of the test is that it is very specific,” said Dr. Mario Philipp, chairman of the Division of Bacteriology and Parasitology at the Tulane National Primate Research Center of Tulane University Health Science Center. Philipp heads the team that pioneered C6 research.
By last summer, a human Lyme test based on Tulane’s C6 work had been produced by Immunetics Inc. of Cambridge, Mass., and approved by the federal Food and Drug Administration.
The next step is to determine whether the C6 test is better than the CDC’s current two-stage procedure. Andrew Levin, founder, president, CEO and scientific director of Immunetics, said results of a comparison study funded by the National Institutes of Health should be available this summer.
“Our analysis so far suggests this assay is at least comparable and perhaps better than the two-tiered testing,” he said. It’s simpler, less subjective and likely to be less expensive, he said.
Levin said the C6 test – already available through a number of clinical laboratories in some physicians’ offices – isn’t fooled by the Lyme vaccine, so those who have been vaccinated can get an accurate test.
Karen Forschner, board chairwoman of the Lyme Disease Foundation, of Hartford, said her organization has been following the C6 research – and other new testing technologies – with great interest. “It’s a test that holds great promise,” she said.
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