Sessions

Hard ticks (Acari: Ixodidae) are regarded as the predominant vectors of pathogens in the temperate zone, including most of Europe in the northern hemisphere. Cities of central Europe are well-studied in this context, including such habitats as recreational areas or forests, parks and cemeteries. However, to our knowledge, no studies are available targeting tick populations in or around urban marshes, in part because such habitats are rare. The present study was initiated to collect ticks from the vegetation in an urban marshy biotope of central Europe. During the one-year-long study period, 1960 ticks were collected. The majority of ticks were Ixodes ricinus (n=1037), followed by Dermacentor reticulatus (n=610) and Haemaphysalis concinna (n=313). Ixodes ricinus and D. reticulatus showed activity during both halves of the year, whereas H. concinna was only questing on the vegetation from April to June. Dermacentor reticulatus predominated along the margin of reedbed, while I. ricinus and H. concinna were significantly more common in the two habitats with woods. Molecular analysis of the cytochrome c oxidase subunit I (cox1) gene in 33 D. reticulatus revealed that all except one tick had serial mutations along a 129-bp-long part of the gene. In the 16S rRNA gene, only two D. reticulatus haplotypes were recognized but as many as 11 in case of I. ricinus specimens. Regarding detection of DNA from the blood meal of the previous developmental stage, the following hosts were identified: two urban bird species, the dog, the red fox, the Eurasian shrew, the wild boar, the chicken and humans. Specimens of D. reticulatus and I. ricinus were shown to contain the DNA of Ehrlichia muris, an important zoonotic pathogen. Among rickettsiae, Rickettsia conorii subsp. raoultii was detected in 13% of D. reticulatus. Ixodes ricinus was shown to carry most often the DNA of Rickettsia helvetica, Borrelia lusitaniae and Borrelia afzelii (the latter two causing Lyme disease). Regarding piroplasms, Babesia microti had very high, 36% prevalence in I. ricinus. One of the outstanding results was the unprecedented series of mutations in the cox1, but not in the 16S rRNA gene of D. reticulatus. In this context it is noteworthy that the marshy biotope is next to the runway of an international airport, and kerosene combustion chemicals may have contributed to the environmental contamination of the area, probably including nitrogen derivates that can cause mutations by inducing DNA damage. This is the first report of E. muris in an urban biotope of central Europe. To our knowledge, similarly high local prevalence of B. microti was only reported in ticks in North America, where this piroplasm is responsible for most cases of human babesiosis (unlike in Europe).