In Europe, two tick species of the genus Dermacentor occur, Dermacentor marginatus and Dermacentor reticulatus. When the spatial distribution of both species in Germany was studied comprehensively for the first time in 1976, D. marginatus populations were recorded along the Rhine and Main river valleys in southwestern Germany, while D. reticulatus was very rare. In the last 50 years, however, a considerable range expansion of D. reticulatus has been noted in several European countries. To assess the current distribution of Dermacentor spp. in Germany, citizens were asked to send in ticks suspected to belong to the genus Dermacentor or that were of "unusual" appearance. From February 2019 until February 2020, 3,902 Dermacentor ticks were received in total. Of those, 15.48% (604/3,902) were identified as D. marginatus and 84.24% (3,287/3,902) as D. reticulatus, while 11 specimens could not be identified to species level. The majority of D. reticulatus specimens was collected from dogs (1,212/2,535; 47.12%), while D. marginatus was mostly collected from horses (184/526; 34.98%). Our results confirm that the adults of both Dermacentor species are active all year round. D. reticulatus specimens were sent in from all federal states except the Free and Hanseatic City of Hamburg, while D. marginatus specimens were only received from locations in southwestern Germany. Overall, data obtained from this citizen-science study show that D. reticulatus has significantly expanded its range, especially in northern Germany. Regarding D. marginatus, new locations northwest of the previous range were detected, although the distribution has remained rather stable as compared to D. reticulatus. The spread of D. reticulatus, the vector of Babesia canis, is of major importance for veterinarians and dog owners in terms of canine babesiosis outbreaks or endemization in hitherto B. canis-free areas. Thus, veterinarians and veterinary students need to be informed about the new situation to be able to give adequate advice to dog owners on the extended D. reticulatus range and appropriate control measures.

Transmission of the fox tapeworm Echinococcus multilocularis, the causative agent of human alveolar echinococcosis, is known to depend on various environmental factors which are subject to human influence. Epidemiological data suggest that in most endemic regions anthropogenic landscape changes (e.g. deforestation and agricultural practices) have led to more favourable conditions for the parasite's animal hosts, especially arvicolid rodents, thereby increasing the risk for parasite transmission and human disease. Examples are the conversion of forests or crop fields into meadows and pastures in Europe, China and North America, and overgrazing of natural grassland in central Asia. Other anthropogenic factors include interference with host population densities by wildlife disease control, changing hunting pressure and provision of new habitats, e.g. in urban areas. Domestic dogs may, under certain conditions, get involved in the otherwise largely wildlife-based transmission, and thereby greatly increase the infection pressure to humans. The introduction of neozootic host species may increase transmission, or even initiate the parasite's life-cycle in previously non-endemic regions. Lastly, the parasite itself may be accidentally introduced into non-endemic areas, if suitable host populations are present (e.g. in northern Japan).

SummaryFox baits containing 50 mg praziquantel were distributed by aircraft in a 3000 km 2 area of southwestern Germany from 1995 to 1999. 20 baits / km 2 were initially distributed at intervals of six to twelve weeks. Starting from a prebaiting prevalence of 64 % (95 % C.I. 59 -69), a level of 15 % (C.I. 10 -21) was reached after 18 months. Further decreasing the frequency and discontinuing the bait distribution caused a surge to 55 % (C.I. 49 -61) within 36 months. Other cestode species (Taenia spp., Mesocestoides spp.) showed similar responses, while the prevalence of ascarid nematodes did not decline during baiting. New infections of fox cubs with E. multilocularis, but not with other cestodes, drastically decreased after one year. Prevalences of fox helminths in an external control area remained stable. Our data suggest that repeated praziquantel treatment of free ranging foxes is suitable to reduce the prevalence of E. multilocularis in a large area.

A survey on the prevalence of Echinococcus multilocularis in foxes was conducted in the administrative district of Starnberg (federal state of Bavaria, Germany) and some adjacent municipalities from October 2002 to March 2003. The background to the study was the scarcity of recent data for Bavaria, where, in contrast to neighbouring regions, a general increase in the prevalence of the parasite has not yet been demonstrated. To estimate the current infection rate, a total of 268 shot foxes were examined using the intestinal scraping technique, resulting in an overall prevalence of 51%. This was compared with retrospective data collected during the period from 1989 to 2001. For the corresponding area and season, the retrospective prevalence was estimated at 32%, based on 222 shot foxes. The prevalence and its temporal development differ considerably on small spatial scales. The most conspicuous change has taken place in the western part of the study area, where a previous prevalence of 35% has increased to 80% in 2002/2003.

This paper describes the design and the preliminary evaluation of an integrated approach to the control of Echinococcus multilocularis in foxes using praziquantel bait. Air distribution of bait in agricultural and recreational areas was combined with distribution of bait by hand in towns and villages to cover the entire fox population in the 213-km 2 baiting area. Bait distribution density was 50/km 2 , and bait was distributed once every 4 weeks. Pre-baiting prevalence was 35% (22-50% CI 95%). During a 1-year period following the first 4 months of bait distribution, only one positive fox was found (prevalence 1%; 0-4% CI 95%). No significant change had occurred in the unbaited control area. This prevalence decline is far more pronounced than in previous fox-baiting studies, which is likely to be due to the increased bait distribution density and baiting frequency, and the inclusion of the 'urban' fox population.