Molecular phylogeny supports invalidation of Didelphodiplostomum and Pharyngostomoides (Digenea: Diplostomidae) and reveals a Tylodelphys from mammals

Alaria, Didelphodiplostomum and Pharyngostomoides are among genera of diplostomid digeneans known to parasitize mammalian definitive hosts. Despite numerous recent molecular phylogenetic studies of diplostomids, limited DNA sequence data is available from diplostomids parasitic in mammals. Herein, we provide the first 28S rDNA and cox1 mtDNA sequences from morphologically identified, adult specimens of Didelphodiplostomum and Pharyngostomoides. Newly generated 28S sequences were used to infer the phylogenetic interrelationships of these two genera among other major lineages of diplostomoideans. The phylogeny based on 28S and a review of morphology clearly suggests that Pharyngostomoides should be considered a junior synonym of Alaria, while Didelphodiplostomum should be considered a junior synonym of Tylodelphys. Pharyngostomoides procyonis (type species), Pharyngostomoides adenocephala and Pharyngostomoides dasyuri were transferred into Alaria as Alaria procyonis comb. nov., Alaria adenocephala comb. nov. and Alaria dasyuri comb. nov.; Didelphodiplostomum variabile (type species) and Didelphodiplostomum nunezae were transferred into Tylodelphys as Tylodelphys variabilis comb. nov. and Tylodelphys nunezae comb. nov. In addition, Alaria ovalis comb. nov. (formerly included in Pharyngostomoides) was restored and transferred into Alaria based on a morphological study of well-fixed, adult specimens and the comparison of cox1 DNA sequences among Alaria spp. The diplostomid genus Parallelorchis was restored based on review of morphology.

Roadkills as a Method to Monitor Raccoon Dog Populations

The raccoon dog (Nyctereutes procyonoides) is one of the most frequently killed species on Lithuanian roads. As an invasive species, up-to-date knowledge of population size, trends and spatial distribution is critically important both for species assessment and for the planning of control measures. In Lithuania, however, raccoon dog surveys have not been carried out since 1997. We investigated, therefore, whether roadkill counts on predefined routes could be used as a proxy for a survey. Our dataset includes survey numbers for the period 1956-1997, hunting bag sizes for 1965-2020 (including the spatial distribution of the hunting bag in 2018-2020) and roadkill data relating to 1551 individuals between 2002-2020. At the most local scale, that of the hunting areas of hunting clubs, correlations between the numbers of hunted and roadkilled individuals were negative and insignificant or absent. At the country scale, however, we found significant correlation both between the numbers surveyed and hunted in 1965-1997 (r = 0.88), and between those hunted and the number of roadkills in 2002-2020 (r = 0.56-0.69). Therefore, we consider that roadkill counts on predefined and stable routes may be used as a proxy for a survey at the country scale. Practical implementation of the method is proposed.

The raccoon dog (Nyctereutes procyonoides) as a reservoir of zoonotic diseases in Denmark

Raccoon dogs have successfully invaded Europe, including Denmark. Raccoon dogs are potential vectors and reservoir hosts of several zoonotic pathogens and thus have the potential for posing a threat to both human and animal health. This study includes analysis of four zoonotic parasites, 16 tick-borne pathogens and two pathogen groups from 292 raccoon dogs collected from January 2018 to December 2018. The raccoon dogs were received as a part of the Danish national wildlife surveillance program and were hunted, found dead or road killed. The raccoon dogs were screened for Alaria alata and Echinococcus multilocularis eggs in faeces by microscopy and PCR, respectively, Trichinella spp. larvae in muscles by digestion, antibodies against Toxoplasma gondii by ELISA and screening of ticks for pathogens by fluidigm real-time PCR. All raccoon dogs tested negative for E. multilocularis and Trichinella spp., while 32.9% excreted A. alata eggs and 42.7% were T. gondii sero-positive. Five tick-borne pathogens were identified in ticks collected from 15 raccoon dogs, namely Anaplasma phagocytophilum (20.0%), Babesia venatorum (6.7%), Borrelia miyamotoi (6.7%), Neoehrlichia mikurensis (6.7%) and Rickettsia helvetica (60.0%). We identified raccoon dogs from Denmark as an important reservoir of T. gondii and A. alata infection to other hosts, including humans, while raccoon dogs appear as a negligible reservoir of E. multilocularis and Trichinella spp. infections. Our results suggest that raccoon dogs may be a reservoir of A. phagocytophilum.

Radiographic evaluation of congenital vertebral anomalies in Korean raccoon dogs (Nyctereutes procyonoides koreensis)

Background

The normal vertebral anatomy of Korean raccoon dogs and their variants require research attention as a prerequisite for identifying pathologies and anomalies.

Objectives

This retrospective study aimed at describing the vertebral formula and congenital vertebral anomalies in Korean raccoon dogs (Nyctereutes procyonoides koreensis).

Methods

Radiographs of 82 raccoon dogs (42 males, 40 females) acquired from May 2013 to June 2020 in the Gangwon Wildlife Medical Rescue Center were reviewed to evaluate the cervical, thoracic, and lumbar vertebrae of the spine.

Results

Normal morphology of all vertebrae was observed in 50 of the 82 raccoon dogs, and the vertebral formula was cervical 7, thoracic 13, and lumbar 7. Congenital vertebral anomalies were found in 32 raccoon dogs: transitional vertebrae (TV) in 31 and block vertebrae in 2. Two raccoon dogs had 2 types of vertebral anomalies: one had TV and block vertebra, and the other had 2 types of TV. Twenty-nine raccoon dogs had thoracolumbar TV (TTV) and 3 had lumbosacral TV. TTV was morphologically classified into 4 different types: unilateral extra-rib in 5 raccoon dogs, bilateral extra-ribs in 14, bilateral elongated transverse processes in 4, and an asymmetric mixed formation of extra-rib with elongated transverse process in 6.

Conclusions

This study showed that TTV is common in Korean raccoon dogs, and that the vertebral formula is relatively diverse. The bilateral extra-ribs type TTV is the most common variant, which is almost similar to normal rib to be confused the radiographic evaluation.

DNA-based detection of Leptospira wolffii, Giardia intestinalis and Toxoplasma gondii in environmental feces of wild animals in Korea

Leptospira, Giardia intestinalis and Toxoplasma gondii infections are reported in humans and animals worldwide, but molecular surveillance of these pathogens in Korean wildlife is still limited. Here, we examined the prevalence of these pathogens in environmental feces of Eurasian otters, leopard cats and raccoon dogs using nested PCR followed by DNA sequencing. G. intestinalis was detected in all of three animals, while T. gondii was detected only in leopard cats. Leptospira wolffii was detected in raccoon dog and Eurasian otter. Our results suggest that these animals can act as a reservoir of these zoonotic pathogens. Consistent monitoring of these pathogens in wildlife is needed to prevent from their infections in humans and livestock in Korea.

Susceptibility of Raccoon Dogs for Experimental SARS-CoV-2 Infection

Raccoon dogs might have been intermediate hosts for severe acute respiratory syndrome-associated coronavirus in 2002-2004. We demonstrated susceptibility of raccoon dogs to severe acute respiratory syndrome coronavirus 2 infection and transmission to in-contact animals. Infected animals had no signs of illness. Virus replication and tissue lesions occurred in the nasal conchae.

Molecular detection of Anaplasma phagocytophilum in wild carnivores in north-eastern Poland

Background

Anaplasma phagocytophilum is an obligate parasitic intracellular bacterium. It is the causative agent of granulocytic anaplasmosis, with effects on human and animal health. In Europe, the pathogen is mainly transmitted among a wide range of vertebrate hosts by blood-sucking arthropods. The aim of this study was to determine the presence of A. phagocytophilum in wild carnivores, viz raccoon dogs (Nyctereutes procyonoides), badgers (Meles meles), foxes (Vulpes vulpes), martens (Martes sp.) and European polecats (Mustela putorius), using molecular methods.

Methods

In the present study, 174 spleen samples were collected from adult, wild carnivores hunted in the years 2013–2016. A short fragment (383 bp) of the 16S ribosomal RNA gene partial sequence was used as a marker to identify A. phagocytophilum in spleen samples collected from carnivores using nested PCR.

Results

The prevalence of A. phagocytophilum in wild carnivores was 31.61% (55/174). Seven sequences of A. phagocytophilum were generated from two raccoon dogs, two badgers, one marten, one red fox and one European polecat. Six identical nucleotide sequences were obtained from one raccoon dog, two badgers, one marten, one red fox and one European polecat (A. phagocytophilum sequences 1: MH328205–MH328209, MH328211), and these were identical to many A. phagocytophilum sequences in the GenBank database (100% similarity). The second sequence (A. phagocytophilum sequence 2: MH328210) obtained from the raccoon dog shared 99.74% identity with A. phagocytophilum sequence 1.

Conclusions

To our knowledge, this is the first study to use molecular methods to determine the presence of A. phagocytophilum in wild carnivores, viz raccoon dog, badger, marten and European polecat, in Poland. The detected A. phagocytophilum sequences (1 and 2) were closely related with those of A. phagocytophilum occurring in a wide range of wild and domestic animals and vectors.

The occurrence and muscle distribution of Trichinella britovi in raccoon dogs (Nyctereutes procyonoides) in wildlife in the Głęboki Bród Forest District, Poland

The raccoon dog (Nyctereutes procyonoides) is an introduced, invasive species in Europe. Literature data show that raccoon dogs act as a reservoir of many dangerous parasites, including nematodes of the genus Trichinella. The aims of the study were to determine the prevalence of Trichinella spp. infection in raccoon dogs collected from the Głęboki Bród Forest District between 2013 and 2016, and to evaluate their distribution in the muscle tissue of the host. The larvae of Trichinella spp. were detected in 45 raccoon dogs (39.82%), and all of them were identified as T. britovi. No mixed infection was observed. The intensity of infection ranged from 0.02 to 622.92 larvae per gram (LPG), and the highest mean was observed in the tongue and lower forelimb in both examined sexes. The raccoon dog may play a significant role as a reservoir of T. britovi in the wildlife in the examined area.

Genetic Diversity and Population Structure of East Asian Raccoon Dog (Nyctereutes procyonoides): Genetic Features in Central and Marginal Populations

The raccoon dog (Nyctereutes procyonoides) is endemic to East Asia but has been introduced in Europe. Its high adaptability enabled its rapid colonization of European countries, where population growth has been raising concerns regarding ecosystem disturbance and the spread of zoonotic diseases. The genetic diversity and structure of endemic, source, and introduced populations from seven locations across South Korea, China, Russian Far East, Finland (spread to Finland after introduction to European part of Russia from Russian Far East), Vietnam, and Japan (Honshu and Hokkaido) were examined based on 16 microsatellite loci. Two major and significantly different (F_ST = 0.236) genetic clusters were found: continental (South Korean, Chinese, Russian, Finnish, and Vietnamese) and island (Japanese) populations. The continental raccoon dog population comprises three subpopulations (Chinese_Russian_Finnish, South Korean, and Vietnamese) and the Japanese population consists of Honshu and Hokkaido subpopulations. The genetic diversity and geographic structure of raccoon dogs in East Asia has been influenced by natural barriers to gene flow and reveals a typical central-marginal trend in genetic diversity (continental vs. island, and central vs. marginal or source vs. introduced within continental populations). The detected differences between continental and island populations agree with those reported in previous studies that considered these populations as different species.

Population structure of the raccoon dog (Nyctereutes procyonoides) using microsatellite loci analysis in South Korea: Implications for disease management

The prevention and control of infectious diseases transmitted by wildlife are gaining importance. To establish effective management strategies, it is essential to understand the population structure of animals. Raccoon dogs (Nyctereutes procyonoides) in South Korea play a key role in the maintenance of food web stability and possess genetic compositions that are unique compared to those in other areas. However, wild raccoon dogs play another role as the main host of various infectious diseases. To establish long-term strategies for disease management, we investigated the genetic structure and possible geographic barriers that influence the raccoon dog population in South Korea by analyzing 16 microsatellite loci. The present study showed that mountains were the major factors responsible for genetic structuring, along with distance. We proposed potential management units (MUs) for raccoon dogs based on the genetic structuring and gene-flow barrier data obtained in this study. Four MUs were suggested for the Korean raccoon dog population (Northern, Central, Southwestern, and Southeastern). The Korean raccoon dog population structure determined in this study and the proposed MUs will be helpful to establish pragmatic strategies for managing Korean raccoon dog population and for preventing the transmission of infectious diseases.

Questionnaire survey of detrimental fur animal epidemic necrotic pyoderma in Finland

Background

In 2007, a previously unrecorded disease, fur animal epidemic necrotic pyoderma (FENP), was detected in farmed mink (Neovision vision), foxes (Vulpes lagopus) and Finnraccoons (Nyctereutes procyonoides) in Finland. Symptoms included severe pyoderma with increased mortality, causing both animal welfare problems and economic losses. In 2011, an epidemiologic questionnaire was mailed to all members of the Finnish Fur Breeders’ Association to assess the occurrence of FENP from 2009 through the first 6 months of 2011. The aim was to describe the geographical distribution and detailed clinical signs of FENP, as well as sources of infection and potential risk factors for the disease.

Results

A total of 239 farmers (25%) returned the questionnaire. Clinical signs of FENP were observed in 40% (95% CI 34–46%) of the study farms. In addition, the survey clarified the specific clinical signs for different animal species. The presence of disease was associated with the importation of mink, especially from Denmark (OR 9.3, 95% CI 2.6–33.0). The transmission route between Finnish farms was associated with fur animal purchases. Some risk factors such as the farm type were also indicated. As such, FENP was detected more commonly on farms with more than one species of fur animal in comparison to farms with, for example, only foxes (OR 4.6, 95% CI 2.4–8.6), and the incidence was higher on farms with over 750 breeder mink compared to smaller farms (OR 3.8, 95% CI 1.6–9.0). Contact between fur animals and birds and other wildlife increased the risk of FENP on farms. Responses also indicated that blocking the entry of wildlife to the animal premises protected against FENP.

Conclusions

FENP was most likely introduced to Finland by imported mink and spread further within the country via domestically purchased fur animals. Some potential risk factors, such as the type and size of the farm and contact with wildlife, contributed to the spread of FENP. Escape-proof shelter buildings block the entry of wildlife, thus protecting fur animals against FENP.

Electronic supplementary material

The online version of this article (doi:10.1186/s13028-017-0322-z) contains supplementary material, which is available to authorized users.

Severe impact of sarcoptic mange on the movements and space use for one of its most important vector species, the raccoon dog

Sarcoptic mange is a highly contagious zoonotic skin disease that can have severe effect on population dynamics of many wild mammals. However, very little is known about its effect on the activity and space use of infected animals. In this study we equipped two raccoon dogs (Nyctereutes procyonoides) in a mange outbreak area with radio-collars and observed the spatial and temporal effects of sarcoptic mange to these individuals. Initially, the raccoon dogs had no external symptoms of mange infection, but developed these during the study period. One of the raccoon dogs died just 32 and the other 52days after collaring. During a relatively short period before their death, there was an abrupt and drastic decline in their home range size. For one of the animals it started about 1 month before its death and the home range size reduced >1000×, whereas for the other raccoon dog it took place within the last week, decreasing >200×. The daily covered distances also declined considerably. These results indicate that at the later stage sarcoptic mange affected the physiological state of the diseased animals so forcefully that made them almost immobile. Our results show for the first time how rapid and severe could the impact of sarcoptic mange be for one of its most important reservoir and vector species.

Raccoon dog model shows preservation of bone during prolonged catabolism and reduced physical activity

The raccoon dog (Nyctereutes procyonoides) is a promising animal model capable of preventing disuse-induced osteoporosis. Previous data suggest that this species resembles bears in the preservation of bone mass and biomechanical properties during prolonged passivity and catabolism. This longitudinal study examined the osteological properties of tibiae in farm-bred raccoon dogs that were either fed or fasted (n=6 per group) for a 10 week period. Peripheral quantitative computed tomography was utilized and plasma markers of bone turnover measured before fasting and at 9 weeks followed by mechanical testing (three-point bending), micro-computed tomography and Fourier transform infrared imaging at 10 weeks. Passive wintering with prolonged catabolism (body mass loss 32%) had no significant effects on bone mineralization, porosity or strength. The concentration of C-terminal telopeptide of type I collagen, indicative of bone resorption, increased in the plasma of the fasted raccoon dogs, while the bone formation markers were unchanged. The levels of 25-hydroxyvitamin D were reduced in the fasted animals. Based on these data, the preservation of bone in wintering raccoon dogs shares characteristics with that of bears with no apparent decrease in the formation of bone but increased resorption. To conclude, raccoon dogs were able to minimize bone loss during a 10 week period of catabolism and passivity.

Population Structure of the Raccoon Dog on the Grounds of the Imperial Palace, Tokyo, Revealed by Microsatellite Analysis of Fecal DNA

The raccoon dog (Nyctereutes procyonoides, Canidae, Carnivora) is highly adaptable to urban environments. Populations of carnivorans inhabiting urban areas sometimes differ ecologically and genetically from those in rural areas. However, there is little information on urban raccoon dogs. This study focused on raccoon dog populations in Tokyo, one of the most highly urbanized cities in the world. We examined the genotypes of 10 microsatellites for 101 fecal samples from raccoon dogs inhabiting the grounds of the Imperial Palace, a green space in central Tokyo. We successfully genotyped 58 samples originating from 31 individuals. We also analyzed muscle tissue samples from raccoon dogs from the grounds of the Imperial Palace, the Akasaka Imperial Grounds (a green space close to the Imperial Palace), and the surrounding urban area, and then investigated the genetic structure and diversity of these populations, and the genetic differentiation among them. The population on the grounds of the Imperial Palace was genetically differentiated from that in the Akasaka Imperial Grounds, suggesting that the roads and buildings act as barriers to gene flow. In addition, the population on the grounds of the Imperial Palace showed greater genetic difference from that in the surrounding area than that in the Akasaka Imperial Grounds. We speculate that the moats around the Imperial Palace restrict individual ranges within the palace grounds and limit migration and gene flow to other areas.

Impact of anthropogenic pressure on the formation of population structure and genetic diversity of raccoon dog Nyctereutes procyonoides

The raccoon dog Nyctereutes procyonoides experienced an active introduction and acclimatization in the European part of Russia followed by its migration to and colonization in the neighboring countries. Eventually, it has spread rapidly into many European countries. N. procyonoides probably invaded Lithuania from the neighboring countries of Belarus and Latvia where the species was introduced. However, the data on genetic diversity and population structure of the raccoon dogs in the recently invaded territories are still scarce. The objectives of this study were to investigate genetic diversity of N. procyonoides in Lithuania after acclimatization, and to assess the impact of anthropogenic pressure on the formation of population structure. A total of 147 N. procyonoides individuals collected from different regions of Lithuania were genotyped using 17 microsatellite markers. The microsatellite analysis of raccoon dogs indicated high levels of genetic diversity within the population. The Bayesian clustering analysis in STRUCTURE identified 4 genetic clusters among sampled raccoon dogs that could not reveal a clear separation between subpopulations. The widespread distribution of raccoon dogs in Lithuania, high level of genetic variation observed within subpopulations, and low level of variation portioned among subpopulations suggest migration and gene flow among locations. The significant correlation between genetic and geographic distances indicated isolation that reflected the distance between locations. The fencing of highways and very intensive traffic could be barriers to gene flow between the western and eastern sampling areas of raccoon dogs.

Lack of sex-specific movement patterns in an alien species at its invasion front - consequences for invasion speed

Efficient targeting of actions to reduce the spread of invasive alien species relies on understanding the spatial, temporal, and individual variation of movement, in particular related to dispersal. Such patterns may differ between individuals at the invasion front compared to individuals in established and dense populations due to differences in environmental and ecological conditions such as abundance of conspecifics or sex-specific dispersal affecting the encounter rate of potential mates. We assessed seasonal and diurnal variation in movement pattern (step length and turning angle) of adult male and female raccoon dog at their invasion front in northern Sweden using data from Global Positioning System (GPS)-marked adult individuals and assessed whether male and female raccoon dog differed in their movement behavior. There were few consistent sex differences in movement. The rate of dispersal was rather similar over the months, suggesting that both male and female raccoon dog disperse during most of the year, but with higher speed during spring and summer. There were diurnal movement patterns in both sexes with more directional and faster movement during the dark hours. However, the short summer nights may limit such movement patterns, and long-distance displacement was best explained by fine-scale movement patterns from 18:00 to 05:00, rather than by movement patterns only from twilight and night. Simulation of dispersing raccoon dogs suggested a higher frequency of male-female encounters that were further away from the source population for the empirical data compared to a scenario with sex differences in movement pattern. The lack of sex differences in movement pattern at the invasion front results in an increased likelihood for reproductive events far from the source population. Animals outside the source population should be considered potential reproducing individuals, and a high effort to capture such individuals is needed throughout the year to prevent further spread.

Identification and characterization of the toll-like receptor 8 gene in the Chinese raccoon dog (Nyctereutes procyonoides)

TLR8 is an important sensor of single-stranded RNA (ssRNA) from the viral genome and plays an essential role in innate antiviral responses via the recognition of conserved viral molecular patterns. In this report, TLR8 in the Chinese raccoon dog was characterized and analyzed for the first time. The full-length sequence of raccoon dog TLR8 (RdTLR8) cDNA was cloned by rapid amplification of cDNA ends (RACE) and is 3191bp with a 3117-bp open reading frame (ORF) encoding 1038 amino acids. The putative protein exhibits typical features of the TLR families, with 19 leucine-rich repeats (LRRs) in the extracellular domain and a cytoplasmic TIR domain. Comparative analyses of the RdTLR8 amino acid sequence indicated a 73.6-99.4% sequence identity with dog, horse, pig, sheep, cattle, human and mouse TLR8. Phylogenetic analysis grouped 71 mammalian TLR proteins into five sub-families, wherein RdTLR8 was clustered into a monophyletic TLR8 clade in the TLR9 family, which was completely coincident with the evolutionary relationship among mammals. Quantitative real-time PCR analysis revealed extensive expression of RdTLR8 in tissues from healthy Chinese raccoon dogs with the highest expression in the peripheral blood mononuclear cells (PBMCs) and the lowest expression in the skeletal muscle. HEK293 cells cotransfected with a RdTLR8 expression plasmid and an NF-κB-luciferase reporter plasmid significantly responded to the agonist 3M-002, indicating a functional TLR8 homolog. In addition, raccoon dog PBMCs exposed to the canine distemper virus (CDV) wild strain CDV-PS and the TLR8 agonist 3M-002 showed significant upregulation of RdTLR8 mRNA and proinflammatory cytokines TNF-α and IFN-α, suggesting that RdTLR8 might play an important role in the immune response to viral infections in the Chinese raccoon dog.

Detection of Anaplasma phagocytophilum in red foxes (Vulpes vulpes) and raccoon dogs (Nyctereutes procyonoides) from Brandenburg, Germany

Anaplasma phagocytophilum is an obligate intracellular and tick-transmitted bacterium, which causes granulocytic anaplasmosis in animals and humans. Although infection with A. phagocytophilum in domestic animals and vector ticks is documented, there is sparse information on the occurrence of A. phagocytophilum in wild animals. Red foxes (Vulpes vulpes) as well as raccoon dogs (Nyctereutes procyonoides) are wildlife species highly abundant in certain areas of Germany and represent a potential wildlife reservoir for zoonotic diseases. To obtain data about the occurrence of A. phagocytophilum in these animals, red fox and raccoon dog carcasses (hunted or found dead) were collected from January to September 2009 in the Federal State of Brandenburg, Germany. Lung tissue samples were subjected to DNA extraction and were examined for the presence of A. phagocytophilum DNA by means of real-time PCR. Anaplasma phagocytophilum was detected in 10 out of 122 (8.2%) lungs of red foxes and in 3 out of 13 (23%) lungs of raccoon dogs. To the best of our knowledge, A. phagocytophilum was detected for the first time in red foxes and raccoon dogs in Germany.

Endoparasites of the raccoon dog (Nyctereutes procyonoides) and the red fox (Vulpes vulpes) in Denmark 2009-2012 - A comparative study

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Raccoon dogs recently invaded Denmark.

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Raccoon dogs and foxes harboured several helminths, some are zoonotic.

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A markedly different helminth fauna was evident between the two hosts.

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A fox was infected with Echinococcus multilocularis, no Trichinella spp. were detected.

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Wildlife surveillance is a foundation for the protection against communicable parasites.

Invasive species negatively influence the biodiversity of the ecosystems they invade and may introduce pathogens to native species. Raccoon dogs have very successfully invaded Europe, including, recently, Denmark. This study included analyses of gastrointestinal helminths and Trichinella spp. from 99 raccoon dogs and 384 native red foxes collected from October 2009 to March 2012. The sedimentation and counting method used revealed that raccoon dogs and foxes harboured 9 and 13 different helminth species, respectively, of which several known to be zoonotic. Significantly more nematode and cestode species were found in foxes while raccoon dogs had more trematode species. Rodent transmitted parasites were more prevalent in foxes, while amphibian transmitted parasites were more prevalent in raccoon dogs. One fox was infected with Echinococcus multilocularis (0.3%), while no Trichinella spp. were detected in raccoon dogs or foxes. The trematode Brachylaima tokudai was detected for the first time in Denmark in five of 384 foxes (1.3%). Prevalences of Pygidiopsis summa (3.0% and 3.4%) and Cryptocotyle spp. (15.2% and 15.4%) were comparable in raccoon dogs and foxes, respectively. Four helminth species were more prevalent in foxes than in raccoon dogs: Toxocara canis (60.9% and 13.1%); Uncinaria stenocephala (84.1% and 48.5%); Mesocestoides spp. (42.7% and 23.2%); and Taenia spp. (30.7% and 2.0%), respectively. Three helminth species were more prevalent in raccoon dogs than in foxes: Dipylidium caninum (5.1% and 0.3%); Mesorchis denticulatus (38.4% and 4.2%); and Alaria alata (69.7% and 34.4%), respectively. T. canis was more abundant in foxes while A. alata was more abundant in raccoon dogs. The intestinal distribution of a number of helminth species was comparable between hosts, but highly variable between parasite species. Inherent biological factors and host invasion of new areas might have shaped these marked differences in helminth fauna between the invasive raccoon dog and the native red fox.

The biological potential of the raccoon dog (Nyctereutes procyonoides, Gray 1834) as an invasive species in Europe-new risks for disease spread?

Invasive wildlife species have the potential to act as additional host and vector species for infectious diseases. The raccoon dog (Nyctereutes procyonides), a carnivore species that has its origin in Asia, was taken as an example to demonstrate biological and ecological prerequisites which enables an invasive species to occupy a new habitat permanently. Studies conducted during the last 20 years identified a total of 35 species of endoparasites, five ectoparasites, six bacterial or protozoan species, and five viruses found in the subspecies Nyctereutes procyonoides ussuriensis in its original and newly occupied habitat or in Nyctereutes procyonoides koreensis in its original habitat, respectively. With reference to raccoon dogs impact as vector species and the relevance for human and animal health, we selected Trichinella spp., Echinococcus multilocularis, Francisella tularensis, rabies virus, and canine distemper virus for detailed description. Results of studies from Finland and Germany furthermore showed that biological characteristics of the raccoon dog make this carnivore an ideal host and vector for a variety of pathogens. This may result in a growing importance of this invasive species concerning the epidemiology of some transmissible diseases in Europe, including the hazard that the existence of autochthonous wildlife, particularly small populations, is endangered. Potential adverse effects on human and animal health in the livestock sector must also be taken into account. Especially with regard to its potential as a reservoir for zoonotic diseases, the raccoon dog should receive more attention in disease prevention and eradication strategies.

Invasion of the raccoon dog Nyctereutes procyonoides in Europe: History of colonization, features behind its success, and threats to native fauna

We aimed to review the history of the introduction and colonization of the raccoon dog Nyctereutes procyonoides in Europe, the features behind its successful expansion and its impact on native fauna. The raccoon dog quickly colonized new areas after being introduced to the European part of the former Soviet Union. Today it is widespread in Northern and Eastern Europe and is still spreading in Central Europe. Features behind its success include its adaptability, high reproductive potential, omnivory, hibernation in northern areas, multiple introductions with > 9000 individuals from different localities, and tendency to wander enabling gene flow between populations. Firm evidence of the raccoon dog's negative impact on native fauna, such as a reduction in bird populations, is still scarce. Raccoon dogs may destroy waterfowl nests, although a nest predation study in Latvia did not confirm this. Predator removal studies in Finland suggested that the raccoon dog's impact on game birds is smaller than expected. However, raccoon dogs may have caused local extinction of frog populations, especially on islands. Raccoon dogs may compete with other carnivores for food, for example for carrion in winter, or for the best habitat patches. In northern Europe potential competitors include the red fox Vulpes vulpes and the badger Meles meles, but studies of their diets or habitat preferences do not indicate severe competition. The raccoon dog is an important vector of diseases and parasites, such as rabies, Echinococcus multilocularis and Trichinella spp. and this is no doubt the most severe consequence arising from the spread of this alien species in Europe.