PCR analysis for <Emphasis Type="Italic">Wolbachia</Emphasis> in human and canine <Emphasis Type="Italic">Demodex</Emphasis> mites

In many skin diseases such as Demodex folliculitis, rosacea- or steroid-induced rosacea Demodex mites are present in abundance and are at least partially held responsible for causing these disorders. Although it is known that these diseases respond well to tetracyclines, it is unclear if this is due to the antiinflammatory effects of the antibiotics or to an antibacterial effect on so far unknown bacteria within the Demodex mites. As in filariasis, where the response to doxycycline can be explained by the presence of Wolbachia within the filarial nematodes, this study was performed to see whether Wolbachia also use Demodex mites as their hosts. Human and canine Demodex mite samples were taken by skin scrapings and tested by PCR for the presence of Wolbachia DNA. Wolbachia pipientis DNA was used as positive control. In none of the DNA extracts, Wolbachia were detected showing no evidence for the presence of these bacteria in Demodex mites. The response of Demodex aggravated or Demodex caused diseases to tetracyclines seems not to be due to the presence of Wolbachia in Demodex mites in contrast to the results seen in filariasis.     

Noninvasive in vivo detection and quantification of Demodex mites by confocal laser scanning microscopy

Summary Background In many Demodex‐associated skin diseases Demodex mites are present in abundance and seem to be at least partially pathogenic. So far all diagnostic approaches such as scraping or standardized superficial skin biopsy are (semi‐)invasive and may cause discomfort to the patient. Objectives To see whether confocal laser scanning microscopy (CLSM) – a noninvasive method for the visualization of superficial skin layers – is able to detect and quantify D. folliculorum in facial skin of patients with rosacea. Methods Twenty‐five patients (34–72 years of age) with facial rosacea and 25 age‐ and sex‐matched normal controls were examined by CLSM. Mosaics of 8 × 8 mm and 5 × 5 mm were created by scanning horizontal layers of lesional skin and quantification of mites per follicle and per area as well as follicles per area was performed. Results In all patients D. folliculorum could be detected by CLSM and presented as roundish or lengthy cone‐shaped structures. CLSM allowed the quantification of Demodex mites and revealed significant differences (P < 0·0001): the mean number of mites was 165·4 per 8 × 8 mm area and 94·2 per 5 × 5 mm area in the patients compared with 34·7 and 22·4, respectively, in the controls. The corresponding mean number of mites per follicle was 0·7 and 0·8, respectively, in the patients and 0·1 and 0·2, respectively, in the controls. Conclusions With the help of CLSM it is possible to detect, image and quantify Demodex mites noninvasively in facial skin of patients with rosacea.     

Treatment of Demodex‐associated inflammatory skin conditions: A systematic review

Bacterial folliculitis, rosacea, and other common skin conditions have been linked to infestation by Demodex mites (human demodicosis). Currently, there is little guidance for treatment of inflammatory conditions associated with demodicosis. Thus, the objective of this review is to evaluate the efficacy and safety of treatments utilized for Demodex infestation. PubMed (1946 to January 2019) and Embase (1947 to January 2019) were searched with the following term combinations: Demodex mites, Demodex folliculitis, demodicosis, Demodex folliculorum, or Demodex brevis and articles evaluating treatment of body surface colonization with Demodex mites were included. Common interventions used for Demodex infestation include metronidazole‐based therapies, permethrin, benzoyl benzoate, crotamiton, lindane, and sulfur. Short courses of metronidazole taken orally have shown efficacy in reducing Demodex density. Additionally, topical administration of permethrin daily or twice daily was shown to be efficacious across multiple studies. Crotamiton and benzyl benzoate were also efficacious treatments. Several therapies were associated with mild‐to‐moderate skin irritation. Due to limited data, no standard of care can be identified at this time. Efficacious treatment options may include permethrin, crotamiton, benzyl benzoate, and oral metronidazole; however, long‐term efficacy has not been established.     

Demodex mites: Facts and controversies

Because Demodex mites are ubiquitous, their potential as human pathogens has often been ignored. This contribution focuses on the growing body of evidence linking Demodex mites with various skin disorders. Histologically, spongiosis and lymphoid inflammation are regularly seen in follicles containing Demodex mites. In animals, they are well established as a cause of mange, and a human counterpart–demodectic alopecia–appears to exist. There is also a statistical association between Demodex mite density and rosacea, facial itching, and chronic blepharitis. Papulovesicular rosacealike lesions and spiny blepharitis often respond to agents that reduce Demodex numbers. Although these observations are not sufficient to fulfill Koch's postulates, Koch's postulates are also not fulfilled for the association between brown recluse spiders and dermal necrosis or the association between streptococci and guttate psoriasis. The evidence linking Demodex mites to human disease has implications regarding treatment.     

Acute inflammatory Demodex-induced pustulosis in an immunocompetent patient related to topical steroid use

Demodex spp. mites are a common colonizer of sebaceous adult skin. Though usually clinically insignificant, demodicosis may be associated with a wide spectrum of skin diseases in immunocompetent hosts, such as erythematotelangiectatic and papulopustular rosacea, Demodex folliculorum, and blepharitis. We present a case of a healthy 9-year-old boy with an exuberant, inflammatory, Demodex-associated pustular eruption of the face, induced by the use of a high-potency topical steroid and successfully treated with oral ivermectin.     

Demodex-associated bacterial proteins induce neutrophil activation

Summary Background Patients with rosacea demonstrate a higher density of Demodex mites in their skin than do controls. A bacterium isolated from a Demodex mite from a patient with papulopustular rosacea (PPR) was previously shown to provoke an immune response in patients with PPR or ocular rosacea, thus suggesting a possible role for bacterial proteins in the aetiology of this condition. Objectives To examine the response of neutrophils to proteins derived from a bacterium isolated from a Demodex mite. Methods Bacterial cells were lysed and proteins were partially purified by ÄKTA fast protein liquid chromatography. Isolated neutrophils were exposed to bacterial proteins and monitored for alterations in migration, degranulation and cytokine production. Results Neutrophils exposed to proteins from Bacillus cells demonstrated increased levels of migration and elevated release of matrix metalloprotease 9, an enzyme known to degrade collagen, and cathelicidin, an antimicrobial peptide. In addition, neutrophils exposed to the bacterial proteins demonstrated elevated rates of interleukin 8 and tumour necrosis factor‐α production. Conclusions Proteins produced by a bacterium isolated from a Demodex mite have the ability to increase the migration, degranulation and cytokine production abilities of neutrophils. These results suggest that bacteria may play a role in the inflammatory erythema associated with rosacea.     

Positive correlation between serum immunoreactivity to Demodex‐associated Bacillus proteins and erythematotelangiectatic rosacea

Background Rosacea is a chronic inflammatory condition that affects the skin of the face and the eyes. Erythematotelangiectatic rosacea is characterized by flushing, oedema and telangiectasia. Patients with rosacea demonstrate elevated densities of Demodex mites in their skin compared with controls. A bacterium (Bacillus oleronius) isolated from Demodex mites from a patient with papulopustular rosacea has been demonstrated to produce antigenic proteins that may play a role in papulopustular and ocular rosacea. Objectives To establish whether there was a correlation between the reactivity of sera from patients with erythematotelangiectatic rosacea to Bacillus antigens, and to characterize the proteins to which these patients showed reactivity. Methods Serum samples from patients with erythematotelangiectatic rosacea and controls were examined for reactivity to Bacillus proteins by Western blot analysis. Proteins to which the sera reacted were excised from gels, trypsin digested, and putative identities were assigned following liquid chromatography‐mass spectrometry (LC‐MS) analysis. Results Eighty per cent (21/26) of patients with erythematotelangiectatic rosacea showed serum reactivity to the 62‐ and 83‐kDa proteins of B. oleronius, compared with 40% (9/22) of controls (P = 0·004). The 62‐kDa protein was characterized by LC‐MS and showed homology to groEL chaperonin, which provokes a strong immune response in mammals. The 83‐kDa protein showed homology to aconitate hydratase, of which expression is increased in bacteria under oxidative stress, and which is highly immunogenic. Conclusions The majority of patients with erythematotelangiectatic rosacea show serum reactivity to two proteins from B. oleronius, suggesting that this bacterium may play a role in the induction of this condition. The two proteins to which patient sera reacted were found to be similar to a heat shock protein and an enzyme involved in regulating the stress response of the bacterium.     

Study of Demodex mites: Challenges and Solutions

Demodex mites are the largest and most complex organisms of the skin microflora. How they interact with the innate and adaptive immune systems is unknown. Their potential to have a pathogenic role in the causation of human skin disorders causes continued speculation. With growing interest in the microflora of human skin and its relevance to cutaneous health, the role of Demodex mites needs to be better understood. The main challenges facing scientists investigating the role of these organisms and possible solutions are reviewed under the following headings: (1) Determining the mite population in skin, (2) Transporting, extracting and imaging live mites, (3) Maintaining mites viable ex vivo and (4) Establishing methods to determine the immune response to Demodex mites and their internal contents.     

Rosacea: Treatment targets based on new physiopathology data

Over the past 15 years, numerous clinical, epidemiological and physiopathological articles have been published on rosacea. There is now increasing evidence that rosacea is an inflammatory disease characterised by abnormal innate immune response, major vascular changes, and increased colonisation by Demodex mites, along with a genetic predisposition and multiple external aggravating factors. It is thus possible to define treatment targets and possible treatments: 1) permanent vascular changes (medical and instrumental treatments); 2) flushing (betablockers, botulinum toxin); 3) innate immunity (antibiotics, nonspecific antioxidants and anti-inflammatory molecules); 4) a neurovascular component (analgesics, antidepressants); 5) Demodex (antiparasitic drugs); 6) microbiome; 7) skin barrier impairment (cosmetics and certain systemic drugs); 8) sebaceous glands (isotretinoin, surgery); 9) environmental factors (alcohol, coffee, UV exposure). Treatment recommendations are now available in many countries and benefit from the new phenotypic approach to rosacea, in which every sign or symptom is considered separately rather than having to deal with overlapping subtypes. Since the 2000s, many good quality clinical trials have been published in the field of rosacea and many others are still ongoing. Rosacea is a complex disease involving many different mechanisms and with numerous possible treatments, but there are still some important unmet needs with regard to optimal care.     

Demodex mites

Demodex mites are normal inhabitants of human hair follicles. D folliculorum is found predominantly in the follicular infundibulum of facial skin and is typically present in small groups. D brevis, the smaller of the two species, predominates on the trunk, typically as solitarily mites within the sebaceous glands and ducts. In a wide variety of animals, Demodex mites are recognized as a cause of mange. The role of Demodex mites as agents of human disease has been more controversial, but evidence favors their involvement in acneiform eruptions, folliculitis, and a range of eruptions in immunosuppressed patients.     

The significance of Demodex folliculorum density in rosacea

Background Demodex folliculorum has been reported in rosacea in a number of clinical studies. As the Demodex mite is also present in many healthy individuals, it has been suggested that the mite may have a pathogenic role only when it is present in high densities. Moreover, some authors have proposed that a mite density above 5/cm² may be a criterion for the diagnosis of inflammatory rosacea. In this study, the possible role of D. folliculorum and the importance of mite density in rosacea were investigated using a skin surface biopsy technique. Methods Thirty-eight patients with rosacea and 38 age-and-sex-matched healthy subjects entered the study. With the skin surface biopsy technique, we obtained samples from three facial sites. We then determined the mite positivities, the mean mite counts in both study groups, the mean mite densities at each facial site and in the rosacea subgroups, and the mite densities above 5/cm². Results The mean mite count in the rosacea group (6.684) was significantly higher than that in controls (2.868; p < 0.05). The cheek was the most frequently and heavily infested facial region. Ten rosacea patients and five normal subjects had mite densities over 5/cm² ; the difference was not statistically significant (p > 0.05). Conclusions Rosacea is a disease of multifactorial origin, and individual properties may modify the severity of the inflammatory response to Demodex. We suggest that a certain mite density is not an appropriate criterion in the diagnosis of the disease; nevertheless, large numbers of D. folliculorum may have an important role in the pathogenesis of rosacea, together with other triggering factors.     

Density of Demodex folliculorum in rosacea: a case-control study using standardized skin-surface biopsy

A standardized skin-surface biopsy (1 cm²) of the cheek was performed in 49 patients with rosacea [13 with erythematotelangiectatic rosacea (ETR). three with squamous rosacea (SR), 33 with papulopustular rosacea (PPR)], and 45 controls. A mean density of 0.7 Demodex folliculorum/cm² was found in controls, 98% of whom had less than five Demodex/cm². When all clinical types of rosacea were considered collectively, the density of Demodex was significantly higher in patients with rosacea than in controls (mean=10.8/cm²: P<0.001). When the various clinical types of rosacea were considered separately. Demodex density was statistically significantly higher than in controls only in the PPR patients (mean=12.8/cm²; P<0.001). The same type of comparison was also made for three other groups of subjects—patients with isolated inflammatory papules (n=4). rhinophyma (n=3), and HIV infection (n=21), respectively: in these groups, the Demodex density did not differ significantly from controls. The present study demonstrates a high density of D. folliculorum in PPR, and supports its pathogenic role in the papulopustular phase of rosacea. The study suggests that standardized surface biopsy could be a useful diagnostic tool for PPR, with a 98% specificity when Demodex density is higher than 5/cm².     

Erythematotelangiectatic rosacea may be associated with a subclinical stage of demodicosis: a case–control study

Demodex mites are small parasites that live in the skin pores of all adult humans, mainly on the face, and feed on human cells. Demodicosis is a facial skin condition that occurs when the mites proliferate (multiply) abnormally. Demodicosis shows as scales on the skin surface and, when the mites cause inflammation, by redness and/or red or weeping spots. Rosacea is another frequent skin condition affecting more than 10% of the population and characterised by facial redness. Sometimes spots develop and the condition is then called papulopustular rosacea (PPR). The cause of rosacea is still controversial, but it has been suggested that Demodex mites may be involved, because patients with PPR have a high density of mites on the facial skin, similar to patients with demodicosis. In this study, from Belgium, the density of Demodex mites was measured by two successive skin biopsies in patients in the early stage of a condition called erythematotelangiectatic rosacea (ETR), where patients have only redness without spots. The mean densities were lower than the densities in patients with PPR and patients with demodicosis but higher than in patients with healthy skin and patients with other skin conditions. The authors suggest that ETR may favour Demodex proliferation and may represent an early phase of demodicosis, with mites beginning to proliferate but not yet clinically visible. As such, dermatologists should look for Demodex mites in patients with ETR, so that appropriate treatment can be offered if densities are high.     

Human Demodex Mite: The Versatile Mite of Dermatological Importance

Demodex mite is an obligate human ecto-parasite found in or near the pilo-sebaceous units. Demodex folliculorum and Demodex brevis are two species typically found on humans. Demodex infestation usually remains asymptomatic and may have a pathogenic role only when present in high densities and also because of immune imbalance. All cutaneous diseases caused by Demodex mites are clubbed under the term demodicosis or demodicidosis, which can be an etiological factor of or resemble a variety of dermatoses. Therefore, a high index of clinical suspicion about the etiological role of Demodex in various dermatoses can help in early diagnosis and appropriate, timely, and cost effective management.     

Real‐life experience on effectiveness and tolerability of topical ivermectin in papulopustular rosacea and antiparasitic effect on Demodex mites

Ivermectin is a drug approved for the treatment of papulopustular rosacea (PPR). Although clinical guidelines recommend the use of ivermectin as the first‐line treatment in patients with almost clear and mild rosacea, studies concerning its use on them are lacking. This study investigated the effectiveness and the tolerability of ivermectin in almost clear to severe rosacea and assessed the antiparasitic effect on Demodex mites. This is a retrospective study based on 50 patients affected by PPR and treated with topical ivermectin 1% once daily over 16 weeks. The disease severity, the patient‐examined improvement, and the safety assessment of patients were evaluated. Demodex mites were studied with the standardized skin surface biopsy. PPR to all severity achieved a therapeutic success. The number of inflammatory lesions was significantly decreased in almost clear (p < .0001), mild, moderate, and severe (p < .001) forms. A complete remission of inflammatory lesions was achieved by almost clear (p < .001) and mild (p = .005) with 82% with none‐to‐mild cutaneous adverse events. Thirty‐two percent were positive for Demodex mites, and all of them turned negative after 16 weeks. Ivermectin is an effective treatment not only in moderate to severe PPR but also in almost clear/mild rosacea.     

Symptomatic vulvar demodicosis: A case report and review of the literature

Demodex folliculorum is a mite that commonly inhabits the pilosebaceous units of facial skin, particularly in a perioral and periorbital distribution. While typically an incidental and asymptomatic parasite, Demodex spp. are proposed to contribute to the pathogenesis of facial folliculitis, chronic blepharitis and papulopustular rosacea. Reports of demodicosis in anatomic locations other than the face are exceedingly rare. Here we report a 36-year-old woman with symptomatic Demodex spp. infestation of Fordyce spots of the labia minora. She was referred to dermatology after a 9-month history of tender red bumps on the vulva that would arise and drain over a 24 to 72 hours period, several times per week. Physical examination revealed erythema of the labia minora and introitus with a 4 mm, pink, dome-shaped soft papule on the left labium minus. Wet mount, microbiologic cultures and sexually transmitted infection (STI) screenings were unremarkable. Histopathologic examination revealed a well-circumscribed nodule of suppurative granulomatous inflammation arising in a background of mucosa with Fordyce spots, the majority of which were infiltrated by Demodex spp. Treatment with oral ivermectin and topical metronidazole cream resulted in a symptom-free period of 22 months. This case represents an unusual presentation of symptomatic Demodex infestation.     

Endosymbiosis and its significance in dermatology

Proposed at the beginning of the twentieth century to explain the origin of eukaryotic organelles from prokaryotes, endosymbiosis is now medically defined by various interaction patterns between microorganisms and their residing hosts, best exemplified by the bacterial endosymbiont Wolbachia identified in arthropods and filarial nematodes, which can influence normal development, reproduction, survival and transmission of the hosts. Based on the transmission modes, vertical or horizontal, and the function of the endosymbionts, the host–symbiont dependence can be divided into primary or secondary. In dermatology, the role of endosymbionts in skin ectoparasitosis has aroused great interests in the past years. Riesia pediculicola is a primary bacterial endosymbiont in body lice Pediculus humanus, and supplement their hosts with vitamin B, especially pantothenic acid. In cimicosis, the Gram‐negative Wolbachia can synthesize biotin and riboflavin, which are crucial for the growth and reproduction of the bedbug Cimex lectularius. In human demodicosis and rosacea, further study is required to prove the pathogenic role of the Gram‐negative bacteria Bacillus oleronius or the Gram‐positive bacteria Bacillus cereus demonstrated in the Demodex mites. The high infection rate of adult female ticks Ixodes ricinus with the Gram‐negative bacteria Midichloria mitochondrii present in the mitochondria in diverse ovarian cells, with the high seroprevalence rate in tick‐exposed subjects, raises the possibility that this non‐pathogenic endosymbiont may play a role in immune response and successful transmission of the tick‐borne pathogen. The anaerobic protozoan Trichomonas vaginalis and bacteria Mycoplasma hominis are two obligate parasites in the urogenital epithelium, with partially overlapping symptoms. Intracellular localization of Mycoplasma hominis can avoid host immune response and penetration of antibiotics, while Trichomonas vaginalis infected with Mycoplasma hominis seems to have a higher cytopathic activity and amoeboid transformation rate. Further study on the biology and pathogenesis of different endosymbionts in dermatological parasitosis will help for the development of new treatment modalities.     

Demodex folliculitis on the trunk of a patient with mycosis fungoides

A 43-year-old man with tumour Stage mycosis fungoides developed multiple follicular pustules on the trunk during total-skin electron beam therapy. A potassium hydroxide preparation of (he contents of the pustules revealed the presence of Demodex mites. The patient was treated with 6% sulphur lotion with rapid improvement of the cutaneous lesions. We believe that this case represents a pustular folliculitis caused by Demodex mites, Immunosuppression associated with mycosis fungoides and its treatment may have resulted in the proliferation of this obligate parasite of the pilosebaceous follicle, and the development of the folliculitis.     

[Translated article] Association Between Demodex Infestation and Severe Acne Vulgaris: A Cross-Sectional Study of 168 Patients

Background and objectivesInfestation with Demodex mites has been associated with acne vulgaris. The aim of this study was to explore the association between Demodex infestation and severe acne vulgaris in outpatients seen at Hospital Regional Lambayeque in Chiclayo, Peru.Material and methodsWe conducted a cross-sectional study of 46 patients with severe acne and 92 patients with nonsevere acne. Severe acne vulgaris was diagnosed if the score was 3 or more on the Spanish Acne Severity Scale (EGAE, in its Spanish acronym). Demodex infestation was diagnosed when a skin surface biopsy showed more than 5 mites/cm².ResultsThe patients had a median age of 18 years (interquartile range, 15–20 years), 60.9% were male, 81.9% lived in an urban area, and 29.7% were infested with Demodex mites. In the bivariate analysis, severe acne vulgaris was significantly associated with Demodex infestation (P = .001), sex (P = .003), residence (P = .015), a paternal history of acne (P = .045), a maternal history of acne (P = .045), and type of skin (P < .001). In the multivariate analysis, after adjustment for male sex, urban residence, previous treatment, maternal and paternal history of acne vulgaris, and an oily skin type, patients with Demodex infestation were 4.2 times more likely to have severe acne vulgaris (95% CI: 1.6–10.9, P = .003).ConclusionDemodex infestation was associated with severe acne vulgaris in outpatients at our hospital.