Surveillance of Lyme disease borreliae and vector ticks

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We have isolated and characterizedspirochete from skin sample of Australian Lyme disease patient in Sydney area. The isolate was closely related with European Borrelia garinii by comparing its flagellin and rDNA sequences. The outcome indicated that Lyme disease borreliae may also distributed in Australia. We, therefore, investigated tick distribution in Sydney area and infestation of borreliae in Australian tick, Ixodes holocyclus. An internal transcribed spacer (ITS2) sequence between the 5.8S and 28S rRNA genes and mitochondrial rrs sequence were used to estimate the phyletic relationship among Lxodes spp. Tick vectors of Lyme disease-causing Borrelia spirochetes. We found spirochetes in 5% of the tick-mid-gut tissues examined but they did not grow in BSKII medium. PCR amplification using known primer sets for 16S rDNA and/or flagellin gene sequence was also inactive against such tick mid-gut tissue samples. Phyletic analysis by ITS2 sequence indicated that I. Horocyclus is far from the other tick species associated with Lyme disease borreliae. All of out results indicate (1) unknown species of spirochetes is infest in Australian ticks, I. Holocyclus (2) they appear to have a specific association with vector tick species (3) it is not known to transmit the Borrelia-that cause Lyme disease in humans. There is a high degree of concordance in the phylogenetic of Borrelia taxa and the phylogenetic relationships among Oxides ticks, which suggests a history of cospeciation in the tick-spirochete assemblage. The results suggest that the occurrence and distribution of Borrelia in Australia are depend on the vector competence of particular tick species.