Rhipicephalus rossicus and not R. sanguineus is the dominant tick species of dogs in the wetlands of the Danube Delta, Romania.

Changes in the distribution of tick species are among the major causes for the increase in prevalence of zoonotic diseases worldwide, with tick-borne diseases' prevalence showing an emerging pattern. One of these ticks, Rhipicephalus rossicus, which is reported occasionally from humans, seems to be particularly interesting because of its demonstrated vectorial role for zoonotic pathogens like Francisella tularensis, Coxiella burnetii, or CCHF and West Nile viruses. Here we report a case of dominant occurrence of R. rossicus on household dogs in the wetlands of Eastern Europe (Romania). Ticks were collected from dogs in 5 distinct locations, with 1068 ticks of 6 species found. R. rossicus had a dominant occurrence in dogs in all but one location, accounting for 87.1% of all ticks (32.3-95.3% in different locations). Until this study, Rhipicephalus sanguineus was considered as the only important tick species on dogs in south-temperate regions of Europe, as well in Romania. The dominant presence of R. rossicus in dogs, its vectorial competence and broad host spectrum (including humans), make this tick species an important candidate for further analysis and highlight the paucity of our knowledge on disease vectors in this region of Europe.