Sanger Sequencing Revealed Borrelia burgdorferi with FlaB Paralogs Causing Spirochetemia in Early Localized Lyme Disease

It is generally assumed that spirochetemia does not take place at the early localized stage of Lyme disease. This misassumption is due to the lack of sensitive and specific methods for detection. This paper reports that separation of the platelet-rich plasma immediately after venous blood collection to prevent the spirochetes from invading the lymphocytes in the test tube is crucial in molecular detection of a single Borrelia burgdorferi cell spun down in platelet pellets. In 2023, we tested the venous blood specimens of 145 people residing in Lyme disease-endemic areas in the United States. In 98 of them, who were suspected of having early localized Lyme disease irrespective of the absence or presence of a skin lesion, we found 33 specimens (33.7%) positive for B. burgdorferi, including 17 positive for FlaB gene only, 15 positive for both FlaB gene and 16S rRNA gene, and 1 positive for 16S rRNA gene only. Eight (17.0%) of the 47 asymptomatic resident controls were positive for FlaB PCR only. FlaB is a more sensitive chromosomal target than the 16S rRNA gene for the detection of 1-3 B. burgdorferi cells in 1 mL of platelet-rich plasma due to spirochetes gaining or retaining FlaB paralogs at the early localized stage of Lyme disease.