Rickettsia spp. in ticks (Acari: Ixodidae) from wild birds: First detection of Candidatus Rickettsia vini in Hesse, Germany.

Tick-borne diseases are recognized as a growing public health concern and cause significant issues in humans and animals by serving as dispersal agents of ticks and their associated pathogens. Birds contribute to the spread of ticks and tick-borne diseases, with migratory birds playing a role in regional dispersal. Only a few studies have been carried out in Germany so far to investigate tick fauna on birds and the pathogens they harbour. In 2017 and 2018, we collected ticks from a total of 358 birds in the northern region of the Federal State of Hesse, Germany. Most ticks were Ixodes ricinus larvae and nymphs (95.4%). However, two ornithophilic species were also collected: Ixodes frontalis (larvae, nymphs and females) and Ixodes arboricola (larvae and nymphs). Ticks were tested individually or in pools, depending on the tick life stage and species for each bird host, in order to detect tick-borne encephalitis (TBE) virus and Rickettsia spp. All samples tested negative for TBE virus. Of 684 investigated tick pools, 162 tested positive for Rickettsia spp. by screening PCR. Of these, 117 carried Rickettsia helvetica detected by specific real-time PCR. The samples which were negative in the R. helvetica PCR were further investigated using five targets (gltA, 16S, ompA IV, ompB, 23S-5S intergenic spacer region) using multi locus sequence typing and phylogenetic analysis. The obtained sequences showed strong phylogenetic relationship to Candidatus Rickettsia vini, which is most closely related to R. japonica and R. heilongjiangensis, and occur in I. arboricola. Three more sequences were determined as R. helvetica in I. ricinus and I. frontalis. This is the first detection of Ca. R. vini in Germany and the first 23S-5S data published for Ca. R. vini, a useful target for Rickettsia species identification.