[Indication of Borrelia burgdorferi sensu lato in the taiga tick larvae obtained from spontaneously infected females].

Hungry larvae from 17 clutches by spontaneously infected Ixodes persulcatus females were examined by inoculation of the BSK II medium, by microscopy of fixed smears, and by polymerase chain reaction (PCR) with the primers specific toward the conserved sequences of Borrelia burgdorferi 16S ribosomal RNA gene. A study of 781 larvae individually or as pools could not reveal Borrelia DNA by PCR. Inoculations of the BSK II medium with 600 larvae yielded no positive results either; immobile spiral forms of Bacillus spp. were detected in 16 (26.7 +/- 5.7%) cultures of the larvae obtained from 7 females. Microscopy of 1416 fixed smears showed typical Borrelia in 7 (0.5 +/- 0.4%) specimens of larvae resulting from the same hatch; spirochaete-like cells were present in 13 (0.9 +/- 0.5%) cases. The single female from those of the 17 hatches transmitted Borrelia through eggs to filial-generation larvae. The infection rate of the larvae emerged from the eggs of this hatch was 7% and their individual infection rates were 0.4-0.8 Borrelia per 100 fields of vision. The findings suggest that there may a transovarian transmission of Borrelia in I. persulcatus ticks, but its likelihood is very little.