Update and prognosis of distribution in Germany: Nationwide occurrence of .

A considerable range expansion of has been observed in several European countries, which is concerning in the light of its vector function for several pathogens, including and tick-borne encephalitis virus (TBEV). The present study provides an update on the distribution of ticks in Germany, using a citizen science approach. Ticks were collected by citizens from March 2020 to May 2021, and submitted along with information on the date and location of collection, potential hosts and details about the circumstances of discovery. In total, 3,292 specimens were received, of which 76.4% (2,515/3,292) were identified as and 23.0% (758/3,292) as , while 0.6% (19/3,292) were too damaged for species-level identification. was received from all federal states of Germany. Maxent species distribution models predicted suitable environmental conditions for throughout Germany. Findings on the vegetation or on pastured animals without travel history confirmed the occurrence of this tick species as far north as the most northern German federal state Schleswig-Holstein. In contrast, the distribution of still appears to be limited to southwestern Germany, although the northward shift of the distribution limit observed in the preceding citizen science study, as compared with previous published distributions, was confirmed. This shift was also predicted by Maxent species distribution models, reflecting the broader distribution of the tick occurrence data contributed by citizens. Most ticks were found on dogs (1,311/1,960, 66.9%), while was mainly discovered on hoofed animals (197/621, 31.7%) and humans (182/621, 29.3%). Human tick bites were reported in 0.7% (14/1,960) of host-assigned and 3.4% (21/621) of host-assigned . Further studies to investigate an increasing endemisation of in Germany as well as the relevance of for TBEV spread throughout the country, e.g., by traveling dogs, are urgently needed. In view of the activity of during winter or the colder months, which complements that of , a year-round tick protection of at least dogs is strongly recommended.