Lipoptena fortisetosa as a vector of Bartonella bacteria in Japanese sika deer (Cervus nippon).

Background: Two species of deer ked (Lipoptena cervi and L. mazamae) have been identified as vectors of Bartonella bacteria in cervids in Europe and the USA. In an earlier study we showed that Japanese sika deer (Cervus nippon) harbor three Bartonella species, namely B. capreoli (lineage A) and two novel Bartonella species (lineages B and C); however, there is currently no information on the vector of Bartonella bacteria in sika deer. The aim of this study was to clarify potential vectors of Bartonella in Japanese sika deer.

Methods: Thirty-eight wingless deer keds (L. fortisetosa) and 36 ticks (Haemaphysalis and Ixodes species) were collected from sika deer. The prevalence of Bartonella in the arthropods was evaluated by real-time PCR targeting the 16S-23S internal transcribed spacer (ITS) and by culture of the organisms. The total number of Bartonella bacteria were quantified using real-time PCR. The distribution of Bartonella bacteria in deer ked organs was examined by immunofluorescence analysis. The relationship of Bartonella strains isolated from sika deer and arthropods were examined by a phylogenetic analysis based on concatenated sequences of the gltA, rpoB, ftsZ, and ribC genes, followed by a BLAST search for gltA and rpoB.

Results: Bartonella prevalence in deer keds was 87.9% by real-time PCR and 51.5% in culture and that in the ticks was 8.3% by real-time PCR and 2.8% in culture. The mean number of Bartonella bacteria per ked was calculated to be 9.2 × 10 cells. Bartonella aggregates were localized in the midgut of the keds. The phylogenetic analysis and BLAST search showed that both the host deer and the keds harbored two Bartonella species (lineages B and C), while B. capreoli (lineage A) was not detected in the keds. Two novel Bartonella species (lineages D and E) were isolated from one ked.

Conclusions: Lipoptena fortisetosa likely serves as a vector of at least two Bartonella species (lineages B and C), whereas ticks do not seem to play a significant role in the transmission of Bartonella between sika deer based on the lower detection rates of Bartonella in ticks compared to keds. Bartonella species in lineages D and E appear to be L. fortisetosa-specific strains.