Sarcoptic mange in domestic rabbits: Pathogenesis, impact, and control strategies

This review article provides an in-depth examination of sarcoptic mange in domestic rabbits (Oryctolagus cuniculus), a widespread and highly contagious dermatological condition caused by Sarcoptes scabiei var. cuniculi mites. Sarcoptic mange poses significant health risks to rabbits and can lead to severe economic losses in commercial rabbit farming due to decreased productivity, inferior leather quality, and increased mortality rates. Clinical manifestations in rabbits include intense itching, skin lesions, hair loss, and secondary bacterial infections, which can be fatal if left untreated. The immune response in rabbits involves both innate and adaptive components, with keratinocytes playing a crucial role in initiating the response. The adaptive immune response is characterized by a mixed T helper cell profile, leading to inflammation and antibody production, which possibly play a key role in controlling mite infestations. Diagnosis of sarcoptic mange is typically based on clinical signs, supported by microscopic examination of skin scrapings and serological tests. The review emphasizes the risk of transmission to humans, especially those in close contact with infested rabbits, and explores the complex host-parasite immune interplay, detailing how S. scabiei evades the host's immune system through various mechanisms. The review also discusses advanced treatment approaches, focusing on the need for effective control measures to prevent the spread of mange in rabbit populations. The article underscores the importance of further research into the molecular mechanisms of the disease to develop targeted therapeutic interventions.

Effect of the sarcoptic mange upon metabolome profiling in wild boars

Sarcoptic mange is a highly contagious disease and represents one of the main health concerns for humans and non-human mammals worldwide. It is caused by the mite Sarcoptes scabiei and can course with different morphological and physiological presentations. Accordingly, aside from skin inflammation, hosts may experience changes in body condition, immune system, biochemistry, reproduction, and thermoregulation, although the understanding of the downstream metabolic burden is still missing. In this context, mange-derived fat store depletion and following imbalance of fatty acid composition might contribute to the severity of the illness. The lack of a tool for early detection of this etiological agent often results in significant financial losses for farmers and harm to animal welfare. Therefore, using targeted LC-MS/MS-based metabolomics approach, we sought to investigate the impact of sarcoptic mange upon metabolome profiling in the blood serum of mangy wild boars. Thirteen wild boars were analyzed in three different clinical conditions, namely when they were sick, during the therapeutic treatment with ivermectin, and when they were deemed recovered from the disease. We identified specific long-chain acylcarnitines highly abundant in the blood serum of the subjects within the infection phase, when compared to the ivermectin-treated and healthy conditions. Overall, data from our preliminary study highlighted the need for more accurate and broad-based studies, about the potential role of the long chain acylcarnitines in the metabolic homeostasis, to help early diagnose of the sarcoptic mange.

Genomics reveal local skin immune response key to control sarcoptic mange in Iberian ibex (Capra pyrenaica)

BACKGROUND

Sarcoptic mange is an emerging and neglected contagious skin disease caused by the mite Sarcoptes scabiei, affecting humans, domestic animals, and wildlife. Mange is the main disease and a major concern for the management and conservation of populations of Iberian ibex (Capra pyrenaica), a medium-sized mountain ungulate endemic to the Iberian Peninsula and Northern Pyrenees. Differences in host-parasite interaction and host immune response determine mange clinical outcome, but little is known about the related differences in gene expression. This study determined blood and skin gene expressions in S. scabiei-experimentally infested Iberian ibexes.

RESULTS

Infestation with S. scabiei promoted immune and inflammatory genomic responses both in skin and blood, with two different clinical outcomes: either severe infestation or recovery. Sarcoptes scabiei induced local skin immunosuppression to favour its multiplication and establishment of the infestation in the host. Skin gene expression was mostly inflammatory and inefficient to control mange in the severely infected ibexes. Conversely, the immune skin response of the recovered ibexes effectively recognised S. scabiei and activated T-cells, limiting the infestation. Consequently, inflammation-related genes were more expressed in the blood of the severely infested ibexes than in those that recovered.

CONCLUSIONS

The results demonstrate that skin local cellular immune response is key to control sarcoptic mange and prevent the systemic spread of the disease and the associated inflammatory response. These results will be useful to understand the pathogenesis and drivers of the differential outcome of mange at individual scale, and the population and ecological consequences of such variability in Iberian ibex, as well as in other wildlife species, domestic animals, and humans.

The use of haystacks by wolves may facilitate the transmission of sarcoptic mange

Wildlife that use anthropogenic resources often come into conflict with humans, e.g. due to damaged property, habituation or transmission of pathogens, amongst them Sarcoptes scabiei, the aetiological agent of sarcoptic mange, an emerging panzootic skin disease. This study examines the use of haystacks intended for supplementary feeding of European bison (Bison bonasus) by wolves (Canis lupus) with sarcoptic mange and the potential role of this behaviour in skin parasite transmission and human-wolf conflict. Hay samples from the beds used by wolves were found to harbour S. scabiei mites, even several days after the last use. Our data demonstrate an unforeseen link between wild ungulate supplementary feeding and wolf behaviour that may lead to conflict, namely approaching human settlements. However, no negative interactions were observed between wolves and humans or domestic animals. The presence of S. scabiei mites in haystacks provides a potential for its human-facilitated environmental transmission among wildlife and to domestic animals.

Histone deacetylase 2 and 3 of Sarcoptes scabiei: characterization of a potential drug target

Scabies is a contagious zoonotic parasitic disease that causes a substantial risk to both human and animal health and results in significant financial losses. No vaccine is available for scabies, and drug resistance to the conventional treatment for the disease has increased. Histone deacetylase (HDAC) modifies proteins by removing acetyl moieties from histones, regulates transcription, and is crucial for the immune system and apoptotic processes. This study aimed to clone, express, and determine the immunoreactivity of HDAC-2 and HDAC-3 of scabies mites to investigate their potential as scabies drug targets. The effects of inhibitors on recombinant Sarcoptes scabiei HDAC-2 (rSsHDAC-2) and rSsHDAC-3, as well as on the survival rate and ultrastructure of scabies mites in vitro, were also verified. The findings showed that the inhibitors reduced the acetylase activity of rSsHDAC-2 and rSsHDAC-3. Additionally, these inhibitors could significantly reduce the survival rate of scabies mites, making structural alterations in the mites such as mitochondrial pyknosis and cytoplasmic vacuoles and reaching a fatality rate of 76.7% after 24 h of action. In conclusion, HDAC-2 and HDAC-3 were critical to the survival of scabies mites and might be targeted by medications. Furthermore, the effect of inhibitors on the survival rate and structure of isolated scabies mites provides a new direction for developing therapeutic drugs for scabies.IMPORTANCEIn this study, we successfully cloned and expressed recombinant SsHDAC-2 and SsHDAC-3 in a prokaryotic system and confirmed their acetylation-deacetylase activities. These results provide a solid experimental foundation for subsequent research on SsHDAC-2 and SsHDAC-3. Furthermore, we report for the first time the use of SsHDAC-2 and SsHDAC-3 as drug targets. We demonstrated that the inhibition of these HDACs by pharmacological agents can lead to structural damage in the parasite, thereby impacting the survival activity of the scabies mite. This finding opens up a novel therapeutic avenue for the treatment of scabies.

A retrospective epidemiological study of sarcoptic mange in koalas (Phascolarctos cinereus) using wildlife carer admission records

Outbreaks of sarcoptic mange are sporadically reported in koala populations across Australia, but disease characteristics (e.g., distribution across the body) remain poorly understood. In an area of Northern Victoria regular cases coming into care suggest mange may have become enzootic, and here we characterise those koala mange admission records. In 18% (n = 10) of mange affected koala reports that had a recorded outcome (n = 55), the animals died before the carers could locate them, and of the remaining 45 koalas that were alive upon carer arrival, 80% (n = 36) had to be euthanised due to severe mange. The number of admissions varied among years (highest observed in 2019), and over 60% of affected koala admissions were male. Male admissions peaked in austral spring and again in late austral summer-autumn (mating and birthing seasons), with female admissions only exhibiting the latter peak (birthing season). Fissures of the epidermis of the front paws occurred in 100% of admitted koalas, with 70% also showing these signs elsewhere on ventral surfaces or limbs. Only male koalas had signs of mange on the chest and face, and only female koalas had signs of mange on their back. Collectively, this study suggests sarcoptic mange can be a severe disease in koalas, and that male koalas may play an important role in seasonal transmission dynamics. We discuss how these findings may help inform intervention strategies.

Feline sarcoptic mange in Poland: A case series of three cats

BACKGROUND

Sarcoptic mange is rare in cats. The main symptoms reported in cases of feline sarcoptic mange include crusty lesions and pruritus, although these may vary in severity among individuals.

OBJECTIVES

This report describes three cats infested with Sarcoptes scabiei, all presenting with pruritus and excoriation.

METHODS

The diagnosis was confirmed by microscopic observation of skin scrape samples.

RESULTS

All three cats were treated successfully using moxidectin and imidacloprid, selamectin and ivermectin, respectively.

CONCLUSIONS

The clinical presentation of feline scabies appears to be more variable in cats than in dogs. Infestation with S. scabiei should be considered a differential diagnosis for cats presenting with pruritic inflammatory skin disease.

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.

Host, environment, and anthropogenic factors drive landscape dynamics of an environmentally transmitted pathogen: Sarcoptic mange in the bare-nosed wombat

Understanding the spatial dynamics and drivers of wildlife pathogens is constrained by sampling logistics, with implications for advancing the field of landscape epidemiology and targeted allocation of management resources. However, visually apparent wildlife diseases, when combined with remote-surveillance and distribution modelling technologies, present an opportunity to overcome this landscape-scale problem. Here, we investigated dynamics and drivers of landscape-scale wildlife disease, using clinical signs of sarcoptic mange (caused by Sarcoptes scabiei) in its bare-nosed wombat (BNW; Vombatus ursinus) host. We used 53,089 camera-trap observations from over 3261 locations across the 68,401 km2 area of Tasmania, Australia, combined with landscape data and ensemble species distribution modelling (SDM). We investigated: (1) landscape variables predicted to drive habitat suitability of the host; (2) host and landscape variables associated with clinical signs of disease in the host; and (3) predicted locations and environmental conditions at greatest risk of disease occurrence, including some Bass Strait islands where BNW translocations are proposed. We showed that the Tasmanian landscape, and ecosystems therein, are nearly ubiquitously suited to BNWs. Only high mean annual precipitation reduced habitat suitability for the host. In contrast, clinical signs of sarcoptic mange disease in BNWs were widespread, but heterogeneously distributed across the landscape. Mange (which is environmentally transmitted in BNWs) was most likely to be observed in areas of increased host habitat suitability, lower annual precipitation, near sources of freshwater and where topographic roughness was minimal (e.g. human modified landscapes, such as farmland and intensive land-use areas, shrub and grass lands). Thus, a confluence of host, environmental and anthropogenic variables appear to influence the risk of environmental transmission of S. scabiei. We identified that the Bass Strait Islands are highly suitable for BNWs and predicted a mix of high and low suitability for the pathogen. This study is the largest spatial assessment of sarcoptic mange in any host species, and advances understanding of the landscape epidemiology of environmentally transmitted S. scabiei. This research illustrates how host-pathogen co-suitability can be useful for allocating management resources in the landscape.

Density independent decline from an environmentally transmitted parasite

Invasive environmentally transmitted parasites have the potential to cause declines in host populations independent of host density, but this is rarely characterized in naturally occurring populations. We investigated (1) epidemiological features of a declining bare-nosed wombat (Vombatus ursinus) population in central Tasmania owing to a sarcoptic mange (agent Sarcoptes scabiei) outbreak, and (2) reviewed all longitudinal wombat-mange studies to improve our understanding of when host population declines may occur. Over a 7-year period, the wombat population declined 80% (95% CI 77-86%) and experienced a 55% range contraction. The average apparent prevalence of mange was high 27% (95% CI 21-34), increased slightly over our study period, and the population decline continued unabated, independent of declining host abundance. Combined with other longitudinal studies, our research indicated wombat populations may be at risk of decline when apparent prevalence exceeds 25%. This empirical study supports the capacity of environmentally transmitted parasites to cause density independent host population declines and suggests prevalence limits may be an indicator of impending decline-causing epizootics in bare-nosed wombats. This research is the first to test effects of density in mange epizootics where transmission is environmental and may provide a guide for when apparent prevalence indicates a local conservation threat.

Fine-Scale Landscape Epidemiology: Sarcoptic Mange in Bare-Nosed Wombats (Vombatus ursinus)

Landscape epidemiology provides a valuable framework to interpret, predict, and manage spatiotemporal patterns of disease. Yet, owing to the difficulty of detecting pathogen occurrence in free-ranging wildlife, disentangling the factors driving disease dynamics remains a considerable challenge, particularly at fine spatial scales. Here, we investigated the fine-scale landscape epidemiology of sarcoptic mange—a visually apparent disease caused by the mite Sarcoptes scabiei—in bare-nosed wombats (Vombatus ursinus), by: (1) characterizing the distribution and density of wombats within the landscape and (2) examining the effect of environmental variation on the occurrence and apparent prevalence of mange. Wombats were heterogeneously distributed over 19.4 km of transect space (0.096–1.39 wombats ha−1) and seven months of time (increasing by a factor of 1.76). Wombat density was negatively associated with distance to vegetation cover, supporting a general propensity for wombats to occur and burrow near vegetation (native and exotic, excluding pasture). The apparent prevalence of mange varied spatially (3.1–37.5%), with the probability of disease greater in wombats with minimal vegetation and low-lying pans in their estimated home range. We observed trends of increased prevalence in areas with more burrows available per wombat and in individuals occurring near vegetation cover (although not within their home range). Wombat density and active burrow density did not influence the prevalence of mange. This research emphasizes the fine scale at which spatiotemporal patterns of disease can manifest and is the first to investigate the influence of host density for any species with indirect transmission of S. scabiei. Collectively, our results suggest that individuals inhabiting less optimal habitat (pasture) may be at greater risk of disease, or that diseased wombats may be competitively excluded from more optimal habitat (vegetated areas). We discuss implications for understanding and managing mange in wombats and cross-applicability to other mange-affected species with environmental transmission.

Spatio-temporal and transmission dynamics of sarcoptic mange in an endangered New World kit fox

Sarcoptic mange poses a serious conservation threat to endangered San Joaquin kit foxes (Vulpes macrotis mutica). After first appearing in Bakersfield, California in spring 2013, mange reduced the kit fox population approximately 50% until the epidemic ended with minimally detectable endemic cases after 2020. Mange is lethal and thus, with such a high force of infection and lack of immunity, it remains unclear why the epidemic did not burn itself out rapidly and how it persisted so long. Here we explored spatio-temporal patterns of the epidemic, analyzed historical movement data, and created a compartment metapopulation model (named "metaseir") to evaluate whether movement of foxes among patches and spatial heterogeneity would reproduce the eight years epidemic with 50% population reduction observed in Bakersfield. Our main findings from metaseir were that: 1) a simple metapopulation model can capture the Bakersfield-like disease epidemic dynamics even when there is no environmental reservoir or external spillover host, 2) the most impactful parameter on persistence and magnitude of the epidemic is the projection, β/αβ (transmission over decay rate of transmission over space), 3) heterogeneity in patch carrying capacities changes the critical value of the projection needed to achieve an epidemic but makes little difference to epidemic persistence time, and 4) the epidemic is relatively insensitive to birth rates and density vs. frequency-dependent transmission. Our model can help guide management and assessment of metapopulation viability of this vulpid subspecies, while the exploratory data analysis and model will also be valuable to understand mange in other, particularly den-occupying, species.

Sarcoptic mange is an emerging threat to biodiversity in the Qinling Mountains in China

Sarcoptic mange, a disease caused by the burrowing mite Sarcoptes scabiei, is globally endemic and an emerging threat to wildlife. Although many studies have shown that wildlife diseases play key roles in biodiversity conservation, knowledge about sarcoptic mange is still insufficient. In this study, we aim to improve the understanding of the impacts of sarcoptic mange on wildlife populations, the mechanisms involved in its eco-epidemiology and the associated risks to public and ecosystem health by investigating mass death events in gorals and serows in the Qinling Mountains. We conducted interviews with practitioners and local people in the central Qinling Mountains. From the same locations, we collected 24 cutaneous samples from various animals and surveillance data from infrared cameras. Pathological, parasitological and microbiological examinations of the samples were performed. Mite-induced cutaneous lesions, mites and eggs were observed in samples from dead gorals and one dead serow but not in other species. Molecular analysis confirmed the mites to be S. scabiei and shared the same cox 1 genotype. The data obtained from the interviews and infrared cameras indicated that the death of wildlife was related to sarcoptic mange infection and that there had been a decrease in the goral population since the outbreak of the disease. We confirmed that sarcoptic mange was the major cause of the mass death events and may have spread from the western to eastern Qinling Mountains. Based on our findings, we propose several protection strategies to help preserve biodiversity in the Qinling Mountains.

Characterising a sarcoptic mange epizootic in quenda (Isoodon fusciventer)

Sarcoptic mange, a parasitic skin disease caused by Sarcoptes scabiei, is an emerging conservation threat to some Australian wildlife species. As a zoonotic and multi-host disease, it has the capacity to exploit different hosts, creating management challenges for susceptible wildlife populations that may suffer high rates of morbidity and mortality. Sarcoptic mange was identified in quenda (Isoodon fusciventer) in a peri-urban region of Perth, Western Australia in 2019. By mid-2021, reported cases were distributed across 107ha. This retrospective study reviews the spatiotemporal distribution, clinical signs and risk factors for sarcoptic mange in quenda from a metropolitan region. Preliminary epidemiological parameters for the outbreak are described, including period prevalence of infested individuals, spatiotemporal analyses, clinical signs of mange, and preliminary risk factor analyses. The period prevalence of sarcoptic mange between July 1, 2019 and June 30, 2021 was 26.9% (CI 95%; 21.2, 33.5) with a mortality rate of 39.6%, owing to severity of disease or secondary complications. Sarcoptic mange was detected more frequently in adult quenda than juveniles (OR: 176.8, CI 95%: 10.7, 2930.1), with adult males more affected than adult females (OR: 3.5, CI 95%: 1.5, 8.4). Clinical signs of disease presented on the rump and tail (100%), followed by the limbs and digits (61.5%). The most common clinical signs recorded were alopecia (92.3%), erythema (46.2%) and open wounds (42.3%). This is the first documented example of a geographically expanding and propagating epizootic of sarcoptic mange in quenda, with implicit welfare and conservation concerns for the species, alongside potential for cases in humans and domestic species that cohabit with or handle quenda in the urban environment. Further, the detection of cases through wildlife rehabilitation centres highlights the critical role such organisations play in conservation and passive surveillance for wildlife diseases of conservation or public and domestic animal health importance.

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Sarcoptic mange outbreak identified in a population of quenda (Isoodon fusciventer).

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This outbreak is a geographically expanding epizootic.

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It is the first documented example of propagating mange in quenda.

Pathophysiological and Pharmaceutical Considerations for Enhancing the Control of Sarcoptes scabiei in Wombats Through Improved Transdermal Drug Delivery

Sarcoptic scabiei is an invasive parasitic mite that negatively impacts wombats, causing sarcoptic mange disease, characterized by alopecia, intense pruritus, hyperkeratosis, and eventual mortality. Evidence suggests that wombats may be unable to recovery from infection without the assistance of treatments. Transdermal drug delivery is considered the most ideal route of administration for in situ treatment in free-ranging wombats, as it is non-invasive and avoids the need to capture affected individuals. Although there are effective antiparasitic drugs available, an essential challenge is adequate administration of drugs and sufficient drug retention and absorption when delivered. This review will describe the implications of sarcoptic mange on the physiology of wombats as well as discuss the most widely used antiparasitic drugs to treat S. scabiei (ivermectin, moxidectin, and fluralaner). The prospects for improved absorption of these drugs will be addressed in the context of pathophysiological and pharmaceutical considerations influencing transdermal drug delivery in wombats with sarcoptic mange.

Drug dose and animal welfare: important considerations in the treatment of wildlife

A recent publication in Parasitology Research by (Old et al. Parasitol Res 120:1077-1090, 2021) raises the topical and often controversial issue of the treatment of wildlife by personnel with little or no formal scientific training (e.g. wildlife carers). In a valuable contribution to the subject, Old and colleagues document a wide range of topical (pour-on) application doses and frequencies of moxidectin (Cydectin®) administered in situ to bare-nosed wombats (Vombatus ursinus) by members of the wildlife carer/treater community in southeast Australia to treat sarcoptic mange disease. This treatment occurred under minor use permits issued by the Australian Pesticides and Veterinary Management Authority (APVMA). These permits do not require veterinary supervision, although carers are registered and are expected to comply with the guidelines of this permit.The prevalence and severity of sarcoptic mange in wildlife is influenced by a variety of factors including mite biology, environmental conditions, population density, animal behaviour and immune susceptibility (Browne et al. Bioscience, 2021). In bare-nosed wombats, combinations of these elements play a substantial role in making the treatment of an already difficult disease more complex. (Moroni et al. Parasit Vectors 13:471, 2020) comment that any pharmacological treatment of free-ranging wildlife must consider these factors when assessing their feasibility and implications, especially in the context of emerging drug resistance and potential long-term ecological impacts. As individuals with significant interest in sarcoptic mange and representing a range of professional research and veterinary expertise, we see value in providing expert commentary on this issue.