New DNA test to detect Lyme disease spirochete infection

Published on March 30, 2010 at 4:14 AM · No Comments

Many of the more than 30,000 people a year in the United States with suspected cases of Lyme disease spirochete (bacterial) infection can now take a DNA test developed by a Connecticut scientist/physician and his team that can quickly determine if they test positive for Lyme spirochetes in their blood. This is the first such early Lyme test available, and most insurance companies have already agreed to cover the cost for their members.

“said Connecticut physician Sin Hang Lee, MD.”

The scientific medical paper about the advanced test will be printed in the April 2010 edition of the "American Journal of Clinical Pathology."

"If people are infected with the Lyme spirochetes, and not treated quickly, thousands may suffer for many years from the debilitating effects of the disease. "But if, after infection, the bacteria are identified without delay, the patient can be effectively treated and totally cured," said Connecticut physician Sin Hang Lee, MD.

There have been other PCR tests for early Lyme disease. But this is the first effective one using nested PCR for detection and DNA sequencing to validate the molecular diagnosis, in clinical laboratory medicine. DNA sequencing is accepted as the gold standard for molecular identification, said Dr. Lee.

Dr. Lee, a pathologist, and his colleagues at Milford Hospital (Milford, CT) have developed the first highly sensitive and specific DNA test for the diagnosis of early Lyme disease before the traditional serology lab tests become positive. If the clinician awaits the rising Lyme disease antibody titers (which is normally the case) to make a diagnosis, the diagnosis of Lyme disease may be delayed, or even missed. The literature reports that up to 75% of the patients with acute-phase Lyme disease are negative for the characteristic antibodies, but in fact the percentage is higher, he said.

Lyme disease is spread by black-legged ticks, also known as deer ticks, and is most common in Connecticut, Massachusetts, Maryland, Minnesota, New Hampshire, New Jersey, Delaware, Pennsylvania, New York and Wisconsin, according to the Centers for Disease Control. The spirochete bacteria enter the skin at the location of the tick bite. After an incubation for 3-30 days, the bacteria travel through the skin and may spread to lymph nodes or travel through the bloodstream to other organs and other skin sites.

In technical terms, the new LoTemp® nested polymerase chain reaction (PCR) method detects a genomic DNA of the Lyme disease-causing spirochete in the blood, which is further validated by DNA sequencing. It is the marriage of both that minimizes false-negatives to the lowest possible and eliminates false-positives known to be associated with other Lyme disease DNA tests. Symptomatic patients visiting the emergency department or the walk-in center have the best chance for an early diagnosis by this new test. The waiting for a scheduled visit to the doctor's office usually misses the window of opportunity in DNA detection at the time when the bacteria are circulating in the blood of the patient in early Lyme disease, but only briefly, said Dr. Lee.

Dr. Lee is also now collecting data and writing a second report for publication with Jay Walshon, MD, chairman of Emergency Medicine at Milford Hospital and Jessie Williams, MD, of the Milford Hospital Walk-in Urgent Care Center, to summarize their experience. Milford is a suburban city outside of New Haven, in southern Connecticut. The region has about 600,000 people and is located less than an hour from Old Lyme, from which Lyme disease was named.

Lyme disease is endemic in the suburban towns in and around the Milford area, which although located by Long Island Sound, is also in many areas heavily wooded. Dr. Lee's group reported that 25-50% of the engorged deer ticks removed from the human skin bites in this area were found to be infected by the Lyme disease causing spirochetes, Borrelia burgdorferi.

Although the new method based on the nested PCR technology is highly sensitive in detecting Lyme spirochete DNA, a negative result still does not rule out Lyme disease because spirochetemia is transient and its time points in Lyme borreliosis vary from patient to patient, said Dr. Lee.

Dr. Lee said, "untreated or inadequately treated patients may develop tissue damages in the joints, the heart and the nervous system as a result of the bacterial infection. Since there were no reliable laboratory tests to confirm the clinical diagnosis, Lyme disease has been both over-diagnosed and under-diagnosed. Erroneous over-diagnoses of Lyme disease may cause unnecessary use of antibiotics which are associated with serious undesirable side effects in certain patients." Every positive DNA test result at Milford Hospital is confirmed by DNA sequencing, and the diagnostic signature sequence validated by the GenBank database, said Dr. Lee. The GenBank is an on-line database of publicly available DNA sequence data maintained by the National Center for Biotechnology Information (NCBI), a part of the National Institutes of Health (NIH).

The physicians at the Milford Hospital Emergency Center and Walk-in Urgent Care Center, who see about 40,000 patients a year, usually order the traditional antibody testing and the new DNA test for patients presenting with Lyme disease-like symptoms.

Source:

American Journal of Clinical Pathology

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