A new microscopy technique developed to detect Lyme disease is unable to distinguish infected patients from healthy controls, yielding false-positive results that could lead doctors to over-diagnose a patient, according to research published in the journal Infectious Diseases.
The research follows a previous study suggesting that modified microscopy techniques (LM-method) could detect active cases of Lyme disease, caused by Borrelia bacteria, and Babesia, a tick-borne malaria-like parasite, in just one to two days.
Despite considerable publicity and patient demand for the test in Norway, earlier studies did not include a control group and methods were not validated and ready for use in patients, the researchers charged.
To investigate the reliability of the new test, a group led by Dr. Audun Aase of the Norwegian Institute of Public Health collected blood samples from 21 people who had been suffering from Lyme disease-like symptoms for several years and previously tested positive for Borrelia and/or Babesia by the LM-method, and from a control group of 41 people with no known history of tick bites.
The samples were then masked and analyzed in independent laboratories using a range of diagnostic tests including the LM-method, conventional microscopy, genetic fingerprint testing (PCR), and serology.
The results, according to the researchers, indicated that the new LM-method can trigger false positives, suggesting people have Lyme disease when they really do not.
Using the LM-method, 14 (66 percent) patient-group blood samples and 35 (85 percent) control group samples were judged positive for Borrelia and/or Babesia.
However, only one sample (5 percent) of the patient group and eight samples (20 percent) of the control group tested positive for Borrelia DNA by PCR. None of the samples were positive for Babesia DNA, and conventional microscopy did not identify Babesia in any of the samples.
Lyme disease is the most common tick-borne infection in Europe and North America, with 360,000 cases reported over the last 20 years in Europe alone.
While most people who contract the Lyme disease recover quickly after antibiotic treatment, up to a fifth of patients report persistent symptoms years after they have been told standard tests are negative for the disease, explaining the reported high interest for new diagnostic tests, according to the researchers.
