The status of Demodex cornei: description of the species and developmental stages, and data on demodecid mites in the domestic dog Canis lupus familiaris

Unveiling the Role of Endoplasmic Reticulum Stress Pathways in Canine Demodicosis

Canine demodicosis is a prevalent skin disease caused by overpopulation of a commensal species of Demodex mite, yet its precise cause remains unknown. Research suggests that T-cell exhaustion, increased immunosuppressive cytokines, induction of regulatory T cells and increased expression of immune checkpoint inhibitors may contribute to its pathogenesis. This study aimed to gain a deeper understanding of the molecular changes occurring in canine demodicosis using mass spectrometry and pathway enrichment analysis. The results indicate that endoplasmic reticulum stress promotes canine demodicosis through regulation of three linked signalling pathways: eIF2, mTOR, and eIF4 and p70S6K. These pathways are involved in the modulation of Toll-like receptors, most notably TLR2, and have been shown to play a role in the pathogenesis of skin diseases in both dogs and humans. Moreover, these pathways are also implicated in the promotion of immunosuppressive M2 phenotype macrophages. Immunohistochemical analysis, utilising common markers of dendritic cells and macrophages, verified the presence of M2 macrophages in canine demodicosis. The proteomic analysis also identified immunological disease, organismal injury and abnormalities and inflammatory response as the most significant underlying diseases and disorders associated with canine demodicosis. This study demonstrates that Demodex mites, through ER stress, unfolded protein response and M2 macrophages contribute to an immunosuppressive microenvironment, thereby assisting in their proliferation.

Demodex murilegi and Demodex obliquus, two new specific skin mites from domestic cat Felis catus, with notes on parasitism

The Demodecidae are skin and tissue parasites of mammals with high host, topical, and topographic specificity. They may cause a demodecosis, typically observed in pets and humans. Numerous mammal species have been found to have several, specific demodecids, which inhabit different microhabitats. Thus far, two species have been known from the domestic cat, namely Demodex cati Megnin, 1877 (Acariformes: Demodecidae) and D. gatoi Desch and Stewart, 1999; however, there have been indications for the presence of other demodecid mites in this host. Presently, two other species are described, D. murilegi sp. nov. associated primarily with the skin from the area of lips and nose, and D. obliquus sp. nov. associated with the skin of the lower part of the limb. They exhibit morphological discreteness in terms of qualitative traits significant for Demodecidae taxonomy. Demodex murilegi sp. nov. is larger than both known species, and D. obliquus sp. nov. is intermediate in length between them. It is likely that infection with different Demodex species may result in variable symptoms and courses of demodecosis; however, a correct identification of the species causing the parasitosis is needed to confirm this. Thus, the present study compares the taxonomic traits of four cat demodecid mites.

Morphological and ontogenetic characteristics of Miridex putorii (Acariformes: Demodecidae), a new genus and species of skin mite specific to the European polecat Mustela putorius

Among carnivorans, mites of the family Demodecidae are mainly represented by the eight species of the genus Demodex known to cause demodecosis in domestic dog Canis lupus familiaris Linnaeus, 1758 and domestic cat Felis catus Linnaeus, 1758. However, nine other Demodex species from wild carnivorans are also known; in addition they are only known from few records. Previously unknown demodecid mites have been isolated from European polecats, Mustela putorius Linnaeus, 1758, originating from Germany. The specimens are characterized of by an aedeagus with a posterior end located between the opisthosoma and podosoma and an anterior end in the gnathosoma area, with a genital opening in the epistome area; aedeagus length corresponds to 53% (45–59%) of male body length. The mites were isolated from the head skin in 16 of 21 polecats examined (76.2%), mainly in the mystacial vibrissae area (84.8%) and less often in adjacent areas. However, the mite infestation did not appear to cause skin abnormality. Based on the morphological analysis of the adult mites and their morphological ontogenesis, including significant characteristics in demodecid taxonomy, the mite specimens have been classified as representatives of a new species and genus, described as Miridex putorii gen. nov., sp. nov.

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A new genus for the family Demodecidae.

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A new species and first record from demodecid mites in the European polecat Mustela putorius.

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Peculiar features of males: genital opening located on the gnathosoma and aedeagus constitutes above 50% of body length.

Case series: Efficacy of a formulation containing selamectin and sarolaner against naturally acquired mite infestations (Demodex sp., Ornithonyssus bacoti) in degus (Octodon degus)

Ectoparasite infestations are not common in degus. Two cases are presented here where use of Stronghold® Plus/Revolution® Plus (selamectin and sarolaner topical solution) was successfully administered to a degu (Octodon degus) for treatment of naturally-occurring mite infesations. Selamectin (Stronghold®/Revolution®) has been demonstrated to be effective against naturally-occurring mite infections in dogs and selamectin is approved for use in dogs for the treatment of sarcoptic mange (caused by Sarcoptes scabiei) at a dose of 6 mg/kg. In the first case, a 2.6-years-old female degu housed in a group with four other degus was presented with pruritic skin reactions, restlessness and hairloss. Mites morphologically similar to Demodex sp. were detected in the deep skin scrapings. All four degus were treated with Stronghold® Plus/Revolution® Plus (30 mg/kg selamectin and 5 mg/kg sarolaner) once a week for a total of six treatments. The spot-on was administered topically on the dorsal cervical region. Following treatment the degu presenting with clinical signs showed a rapid improvement with the pruritus and overall dermatitis resolving within 2 weeks of treatment. Skin scrapes and microscopic examination of epidermal debris collected from the affected degu were negative for mites from day 14 onwards. In the second case, a group of four 4-6.5-years-old female and male degus that were housed together were infested with Ornithonyssus bacoti. All animals were treated with 30 mg/kg selamectin and 5 mg/kg sarolaner in four total weekly doses. One week later no living mites were found on the patients or in their environment. The four degus improved visibly, and within three weeks of treatment the skin lesions associated with the infestation subsided. The antiparasiticides showed a satisfactory efficacy and were well tolerated (n = 9 animals treated in a total).

Diagnosis and treatment of demodicosis in dogs and cats: Clinical consensus guidelines of the World Association for Veterinary Dermatology

BACKGROUND

Demodicosis is a common disease in small animal veterinary practice worldwide with a variety of diagnostic and therapeutic options.

OBJECTIVES

To provide consensus recommendations on the diagnosis, prevention and treatment of demodicosis in dogs and cats.

METHODS AND MATERIALS

The authors served as a Guideline Panel (GP) and reviewed the literature available before December 2018. The GP prepared a detailed literature review and made recommendations on selected topics. A draft of the document was presented at the North American Veterinary Dermatology Forum in Maui, HI, USA (May 2018) and at the European Veterinary Dermatology Congress in Dubrovnik, Croatia (September 2018) and was made available via the World Wide Web to the member organizations of the World Association for Veterinary Dermatology for a period of three months. Comments were solicited and responses were incorporated into the final document.

CONCLUSIONS

In young dogs with generalized demodicosis, genetic and immunological factors seem to play a role in the pathogenesis and affected dogs should not be bred. In old dogs and cats, underlying immunosuppressive conditions contributing to demodicosis should be explored. Deep skin scrapings are the diagnostic gold standard for demodicosis, but trichograms and tape squeeze preparations may also be useful under certain circumstances. Amitraz, macrocyclic lactones and more recently isoxazolines have all demonstrated good efficacy in the treatment of canine demodicosis. Therapeutic selection should be guided by local drug legislation, drug availability and individual case parameters. Evidence for successful treatment of feline demodicosis is strongest for lime sulfur dips and amitraz baths.

The Biodiversity of Demodecid Mites (Acariformes: Prostigmata), Specific Parasites of Mammals with a Global Checklist and a New Finding for Demodex sciurinus

Demodecidae are the most specialized parasitic mites of mammals; they typically inhabit the skin, but they have been found in other tissues and organs. They can cause demodecosis (a disease which is hazardous and difficult to cure) in humans, domestic animals and livestock. They are parasites with high host and topical specificity. They have been found for most orders of mammals, and they are common in the populations of numerous host species. Therefore, they not only constitute an important subject of veterinary and medical study, but also comprise an excellent model for faunistic and parasitological analyses concerning different aspects of functioning and evolution of the host–parasite relationship. The current level or knowledge of demodecid mites is irregular and fragmentary, and numerous questions require elaboration and ordering, from the taxonomic diversity to geographic distribution and relations with hosts. Such data may be of use i.a. for the development of more efficient and reliable diagnostic methods, as well as understanding the etiology and pathogenesis mechanisms of demodecosis, currently a contentious issue. The present paper lists all formally-described valid species of demodecid mites, together with other functioning specific names, verified and with comments on their status. This is significant for correct species identification and demodecosis diagnostics. The list has been drawn up on the basis of data acquired in the period 1842−2020. It contains 122 valid species of parasite, including their hosts and geographic distribution, data on parasitism, as well as only the second record of Demodex sciurinus in Eurasian red squirrel Sciurus vulgaris in over 100 years since its initial discovery.

Demodex: a skin resident in man and his best friend

Demodex mites are microscopic arachnids found in the normal skin of many mammals. In humans, it is well established that Demodex mite density is higher in patients with the skin condition rosacea, and treatment with acaricidal agents is effective in resolving symptoms. However, pathophysiology of rosacea is complex and multifactorial. In dogs, demodicosis is a significant veterinary issue, particularly the generalized form of the disease which can be fatal if untreated. In each species, clinical and molecular studies have shown that the host's immunological interactions with Demodex mites are an important, but not fully understood, aspect of how Demodex can live in the skin either as a harmless commensal organism or as a pathogenic agent. This review outlines the role of Demodex mites in humans and dogs, considering morphology, prevalence, symptoms, diagnosis, histology treatment and pathogenesis.

Demodex melesinus (Acariformes: Demodecidae) - the forgotten European badger parasite, rediscovered after 100 years

Among 15 demodecid mite species (Acariformes: Demodecidae) recorded from carnivorans Carnivora, 3 species were described from mustelids Mustelidae. They are known only from single records, for which Demodex erminae has been described from the stoat Mustela erminea from Great Britain and New Zealand, D. melesinus from the European badger Meles meles known solely from Great Britain and D. lutrae discovered in the Eurasian otter Lutra lutra from Poland. The current record confirms the existence of D. melesinus, in badger from Poland, after close to one hundred years from its original description, as well as the first detection of the male for this species.