Epizootic of sarcoptic mange in raccoon dogs (Nyctereutes procyonoides) in relation to population density

Camera traps reveal a high prevalence of sarcoptic mange in red foxes from northern Spain

The mite Sarcoptes scabiei affects numerous mammal species causing the sarcoptic mange, a widespread disease with relevance for wildlife conservation, welfare, and management. The red fox (Vulpes vulpes) could become infested by direct and indirect routes leading to external skin lesions potentially recognizable by devices such as camera traps (CTs). In the present study, 86 randomly placed CTs were used to investigate the apparent prevalence and severity of S. scabiei in a red fox population from northern Spain. Their potential environmental and population-related drivers were also assessed. A total of 341 independent encounters were examined to visually identify mange-compatible lesions. The apparent prevalence was 19.16% (confidence interval (CI) 95%: 15.08-23.80) of which 82.81% (CI95%: 71.33-91.10) were severe. Our results revealed that habitat attributes such as lower altitudes, higher coverage of water-linked habitats and woodland predominance, were significant predictors of the apparent risk of mange. The models also suggested that the apparent prevalence of mange was associated with poor body condition and elevated frequencies of spatial coincidence among fox encounters, which facilitates indirect transmission. Interestingly, we did not observe mange-compatible lesions in other sympatric wild species (>15,000 encounters examined). This could be explained by the mite's host specificity and the low probability that these other potential hosts use sites where transmission among foxes usually occurs, such as dens. This study illustrates how camera trapping can be used as an interesting tool for the surveillance of wildlife diseases, thus overcoming the logistic constraints derived from direct sampling and allowing the early detection and better management of pathogens in the riskiest areas.

Malicious Mites-Sarcoptes scabiei in Raccoon Dogs (Nyctereutes procyonoides) in Schleswig-Holstein, Germany

Sarcoptic mange was detected in five free-ranging raccoon dogs (Nyctereutes procyonoides) in the federal state of Schleswig-Holstein, Germany, during a health assessment study of invasive species, including raccoon dogs, carried out between 2021 and 2022. Four raccoon dogs showed severe lesions, including extensive alopecia with thickening and hyperpigmentation of the skin (lichenification). The fifth animal was less affected, showing only thinning of the hair coat in multiple body locations. Skin scrapings were performed and confirmed the presence of Sarcoptes scabiei. Histopathology of the skin revealed diffuse epidermal hyperplasia and hyperkeratosis, mild eosinophilic dermatitis, and varying amounts of intralesional mites. Staphylococcus pseudintermedius and Corynebacterium auriscanis were detected in the skin samples of the affected animals, indicating a secondary bacterial infection. The source of sarcoptic mange remains unclear; interspecies transmission via direct or indirect contact seems likely. Raccoon dogs are therefore a potential vector for sarcoptic mange, and their behaviour could contribute to disease spread and persistence.

Pharmacokinetic and pharmacodynamic considerations for treating sarcoptic mange with cross-relevance to Australian wildlife

Sarcoptes scabiei is the microscopic burrowing mite responsible for sarcoptic mange, which is reported in approximately 150 mammalian species. In Australia, sarcoptic mange affects a number of native and introduced wildlife species, is particularly severe in bare-nosed wombats (Vombatus ursinus) and an emerging issue in koala and quenda. There are a variety of acaricides available for the treatment of sarcoptic mange which are generally effective in eliminating mites from humans and animals in captivity. In wild populations, effective treatment is challenging, and concerns exist regarding safety, efficacy and the potential emergence of acaricide resistance. There are risks where acaricides are used intensively or inadequately, which could adversely affect treatment success rates as well as animal welfare. While reviews on epidemiology, treatment strategies, and pathogenesis of sarcoptic mange in wildlife are available, there is currently no review evaluating the use of specific acaricides in the context of their pharmacokinetic and pharmacodynamic properties, and subsequent likelihood of emerging drug resistance, particularly for Australian wildlife. This review critically evaluates acaricides that have been utilised to treat sarcoptic mange in wildlife, including dosage forms and routes, pharmacokinetics, mode of action and efficacy. We also highlight the reports of resistance of S. scabiei to acaricides, including clinical and in vitro observations.

Two Cases of Mange Mite (Sarcoptes scabiei) Infestation in Long-Tailed Goral (Naemorhedus caudatus) in Republic of Korea

The long-tailed goral, Naemorhedus caudatus (Mammalia: Bovidae), is one of the endangered animals in the Republic of Korea (Korea). Sarcoptic mange mites infested in diverse species of mammals, including humans, but no case has been reported in long-tailed gorals. We report 2 cases of mange mite, Sarcoptes scabiei, infestation in long-tailed gorals. Mange mites were sampled in the skin legions of the 2 long-tailed gorals, which were rescued in 2 different regions, Uljin-gun, Gyeongsangbuk-do and Cheorwon-gun, Gangwon-do, Korea. Our results showed that the ectoparasite was the itch mite that burrowed into skin and caused scabies on the morphological inspection and placed within the phylogenetic relations of the species. The present study confirmed for the first time in Korea that mange mites are pathogenic scabies of long-tailed goral. Closer surveillance of this pathogenic ectoparasite in zoonotic and infectious ecosystems is warranted.

Signs of Rumpwear in the Common Ringtail Possum, Pseudocheirus peregrinus

We report the physical characteristics of rumpwear in the Australian common ringtail possum, Pseudocheirus peregrinus. Rumpwear presents as varying grades of hair breakage and dermatitis on the lumbosacral region. This condition has been reported in Trichosurus spp. (brushtail possums) previously, but never in P. peregrinus. The etiology remains poorly understood.

Logging effects on parasitic infections in a swamp rat (Malacomys edwardsi) in West Africa

Habitat disturbance can have negative impacts on biodiversity, such as reducing species richness. The effects of habitat disturbances on parasite infections of host species, potentially altering their survival rate and thus abundance, are less well known. We examined the influence of forest logging in combination with seasonality, host abundance, host body condition, and host sex, on the community composition of gastrointestinal parasites infecting Edward’s swamp rat, Malacomys edwardsi. Community composition of parasites did not differ between logged and undisturbed sites, but the abundance of some nematodes (i.e., Ascaris and hookworm) was higher in undisturbed than logged sites. The higher abundance of these nematode species implies a changed host-parasite relationship, thus potentially influencing host persistence.

Sustaining Transmission in Different Host Species: The Emblematic Case of Sarcoptes scabiei

Some pathogens sustain transmission in multiple different host species, but how this epidemiologically important feat is achieved remains enigmatic. Sarcoptes scabiei is among the most host generalist and successful of mammalian parasites. We synthesize pathogen and host traits that mediate sustained transmission and present cases illustrating three transmission mechanisms (direct, indirect, and combined). The pathogen traits that explain the success of S. scabiei include immune response modulation, on-host movement capacity, off-host seeking behaviors, and environmental persistence. Sociality and host density appear to be key for hosts in which direct transmission dominates, whereas in solitary hosts, the use of shared environments is important for indirect transmission. In social den-using species, combined direct and indirect transmission appears likely. Empirical research rarely considers the mechanisms enabling S. scabiei to become endemic in host species—more often focusing on outbreaks. Our review may illuminate parasites’ adaptation strategies to sustain transmission through varied mechanisms across host species.

Gastrointestinal Helminths of a European Moose Population in Poland

Parasitic infections have a negative impact on the fecundity and survival of wild ruminants, particularly moose; however, despite being more susceptible to parasitic diseases than other wild cervids, they remain poorly examined in this regard. Therefore, the aim of the present study was to identify gastrointestinal and liver helminth species of the moose population in central Europe, assess the factors contributing to infection intensities and examine their impact on moose health. Abomasum, small intestine, caecum and liver samples were collected from 46 moose in Poland and evaluated for helminth parasite fauna and histopathological changes. Additionally, 289 moose fecal samples were analyzed for the presence of eggs, oocysts and larvae of parasites. In total, 19 parasite taxa were identified. The most prevalent were Mazamastrongylus dagestanica and Ostertagia antipini, which are typical nematodes of moose, together with Spiculopteragia boehmi and O. leptospicularis, characteristic also of other cervids. Parasite species diversity and abomasal parasitic infection intensity were higher in adult moose than in yearlings and calves. The numbers of histopathological lesions depended on the intensity of parasitic infections, and were most severe in the livers of moose infected with Parafasciolopsis fasciolaemorpha. The analysis of fecal samples revealed several regional differences in the levels of parasite eggs, oocysts and larvae shedding. Our findings indicate an accumulation of parasite infections over time in moose, which may be related to high environmental parasite pressure, possibly connected with high moose density and the presence of wetlands; they also serve as the most comprehensive study of moose parasites in central Europe to date.

Sarcoptic mange: An emerging panzootic in wildlife

Sarcoptic mange, a skin infestation caused by the mite Sarcoptes scabiei, is an emerging disease for some species of wildlife, potentially jeopardizing their welfare and conservation. Sarcoptes scabiei has a near-global distribution facilitated by its forms of transmission and use of a large diversity of host species (many of those with broad geographic distribution). In this review, we synthesize the current knowledge concerning the geographic and host taxonomic distribution of mange in wildlife, the epidemiological connections between species, and the potential threat of sarcoptic mange for wildlife conservation. Recent sarcoptic mange outbreaks in wildlife appear to demonstrate ongoing geographic spread, increase in the number of hosts and increased virulence. Sarcoptic mange has been reported in at least 12 orders, 39 families and 148 species of domestic and wild mammals, making it one of the most generalist ectoparasites of mammals. Taxonomically, the orders with most species found infested so far include Perissodactyla (67% species from the entire order), Artiodactyla (47%), and Diprotodontia (67% from this order). This suggests that new species from these mammal orders are likely to suffer cross-species transmission and be reported positive to sarcoptic mange as surveillance improves. We propose a new agenda for the study of sarcoptic mange in wildlife, including the study of the global phylogeography of S. scabiei, linkages between ecological host traits and sarcoptic mange susceptibility, immunology of individuals and species, development of control strategies in wildlife outbreaks and the effects of global environmental change in the sarcoptic mange system. The ongoing transmission globally and sustained spread among areas and wildlife species make sarcoptic mange an emerging panzootic in wildlife. A better understanding of sarcoptic mange could illuminate the aspects of ecological and evolutionary drivers in cross-species transmission for many emerging diseases.

Association of sarcoptic mange with kinship and habitat use in raccoon dogs (Nyctereutes procyonoides)

Although kinship (parent-offspring or siblings) contact has been suggested as a driving factor for sarcoptic mange epizootic in raccoon dogs (Nyctereutes procyonoides), no effect has been reported. In contrast, habitat fragmentation caused by urbanization may result in a high occurrence of sarcoptic mange, because habitat fragmentation may promote contact infection by increasing the population density of raccoon dogs. The habitat distribution of raccoon dogs may therefore influence epizootic sarcoptic mange. The genetic relationship between raccoon dogs was analyzed to examine Sarcoptes scabiei transmission between kin. The relationship between S. scabiei infection and the habitat of raccoon dogs was also investigated. Seventy-five raccoon dogs from Takasaki, Gunma prefecture, were examined from 2012 to 2018; 23 were infested with S. scabiei. The genotypes were determined using 17 microsatellite loci, and the relationships were categorized into four patterns by the ML-Relate software. There was no significant difference between infested pairs and other two pairs (Chi-squared test: χ²=0.034, df=1, P=0.85). Although it was difficult to predicate because the mortality rate was unclear in this study, kinship contact does not seem to be an important factor for sarcoptic mange epizootic. S. scabiei infection rates were significantly associated with the location of village sections (OR=1.55, 95% CI=1.11–2.17, P=0.011). It is suggested that direct/indirect contact between individuals living closely together is an important factor for the transmission of S. scabiei.

Patterns of parasite eggs, oocysts and larvae shedding by moose in the Biebrza marshland (NE Poland)

The study analyses patterns of endoparasite eggs, oocysts and larvae shedding by moose from the relict population in the Biebrza marshland, NE Poland, which has grown to be one of the largest in Central Europe since the ban on hunting imposed in 2001. The analysis identified 10 species or groups of parasites among 230 faecal moose samples collected over 16 consequent months. The most prevalent were the eggs of Trichostrongylidae, Trichuris spp., Nematodirella alcidis, Parafasciolopsis fasciolaemorpha and the larvae of Elaphostrongylus sp. Four parasite species were more prevalent in males, indicating male-biased parasitism, and the studied moose population exhibited a female-skewed sex ratio. Nematodirella alcidis eggs and Protostrongylid larvae were more prevalent during winter, which indicated their resistance to harsh weather conditions. The prevalence of Eimeria alces and Aonchotheca sp. increased during the growing season, as did the number of eggs per gram of faeces (EPG) of P. fasciolaemorpha, possibly due to the availability of water sources. Higher mean monthly temperature was also found to have a positive effect on the excretion of Trichostrongylidae and Moniezia spp. eggs. In addition, the time of infection and the specificity of the parasite life cycle, being sensitive to certain climatic conditions, also appeared to have a strong influence on eggs, oocysts and larvae shedding in this non-harvested moose population.

Examining multiple paternity in the raccoon dog (Nyctereutes procyonoides) in Japan using microsatellite analysis

We analyzed the genotypes of three pregnant females and their litters to investigate the phenomenon of multiple paternity in wild raccoon dogs (Nyctereutes procyonoides) using 17 microsatellite markers. If a female has mated with only one male during estrus, then the maximum number of paternal alleles will not exceed two among littermates with the same father. The results revealed two out of three litters had three or four paternal alleles at one or five microsatellite loci. Therefore, the female had mated with more than one male during estrus. To the best of our knowledge, the present study is the first to report the possibility of multiple paternity in wild raccoon dogs.

MOLECULAR SURVEY OF BARTONELLA ROCHALIMAE IN JAPANESE RACCOON DOGS (NYCTEREUTES PROCYONOIDES VIVERRINUS)

Wild carnivores serve as reservoirs of several zoonotic Bartonella species such as Bartonella henselae, Bartonella vinsonii subsp. berkhoffii, and Bartonella rochalimae. The raccoon dog (Nyctereutes procyonoides viverrinus) is the most common native carnivore in Japan, but epidemiologic studies of Bartonella infections have not been performed in this animal species yet. Here, we report a molecular survey of B. rochalimae prevalence in 619 wild raccoon dogs captured from 2009 to 2017 in western Japan. Bartonella rochalimae DNA was detected in 7.1% (44/619) of the raccoon dogs examined by PCR targeting the rpoB and ssrA genes. All of the sequences obtained were identical in each of the genes. The prevalence of B. rochalimae by sex of the animals was 6.1% (21/344) in male and 8.4% (23/275) in female. The prevalence by year varied from 2% (1/45) in 2011 to 14% (4/28) in 2016. The prevalence (7.9%) of B. rochalimae in the raccoon dogs with sarcoptic mange tended to be higher than the prevalence (4.0%) in the animals without the infestation of mites, although the differences were not significant. Sequence analysis indicated that Japanese raccoon dogs in the area examined were infected with B. rochalimae carrying identical sequences in the rpoB and ssrA genes. In addition, the raccoon dog strain had few sequence variations in both genes compared to other known B. rochalimae strains detected in other parts of the world.

Possible transmission of Sarcoptes scabiei between herbivorous Japanese serows and omnivorous Caniformia in Japan: a cryptic transmission and persistence?

Background

Two transmission patterns of Sarcoptes scabiei in host mammal communities have been reported based on microsatellite-level genetic studies in the last two decades. While one involves restrictions among different host taxa, the other is associated with predator–prey interactions between different host taxa. In contrast to these observations, the present study reports a possible irregular case of transmission of S. scabiei between herbivorous Japanese serow and omnivorous Caniformia mammals in Japan, though under very weak predator–prey relationships.

Methods

DNA from 93 Sarcoptes mites isolated from omnivorous Caniformia (such as the domestic dog, raccoon dog, raccoon and Japanese marten), omnivorous Cetartiodactyla (wild boar) and herbivorous Cetartiodactyla (Japanese serow) in Japan were analyzed by amplifying nine microsatellite markers. Principal components analyses (PCA), Bayesian clustering analyses using STRUCTURE software, and phylogenetic analyses by constructing a NeighborNet network were applied to determine the genetic relationships among mites associated with host populations.

Results

In all the analyses, the genetic differentiation of Sarcoptes mites from wild boars and Japanese serows was observed. Conversely, considerably close genetic relationships were detected between Caniformia-derived and Japanese serow-derived mites. Because the predator–prey interactions between the omnivorous Caniformia and herbivorous Japanese serow are quite limited and epidemiological history shows at least a 10-year lag between the emergence of sarcoptic mange in Japanese serow and that in Caniformia, the transmission of S. scabiei from Caniformia to Japanese serow is highly suspected.

Conclusions

The close genetic relationships among mites beyond Host–taxon relationships and without obvious predator–prey interactions in Caniformia and Japanese serow deviate from previously reported S. scabiei transmission patterns. This type of cryptic relationship of S. scabiei populations may exist in local mammalian communities worldwide and become a risk factor for the conservation of the remnant and fragmented populations of wild mammals.

Electronic supplementary material

The online version of this article (10.1186/s13071-019-3630-5) contains supplementary material, which is available to authorized users.