Density of Demodex folliculorum in perioral dermatitis

Evaluation of the effect of 577-nm pro-yellow laser on demodex intensity

The skin disease of the pilosebaceous unit created by demodex mites is called demodicosis. Recently, it has been brought to the agenda that laser therapies can be effective in reducing the intensity of demodex parasite. With this study, we aimed to evaluate the effect of pro-yellow laser applied to the face on the intensity of demodex parasite. Twenty-five patients who had referred to the dermatology polyclinic with a complaint of rash on the face and who had been given proyellow laser therapy during the past year were included in the study. Average pre-laser therapy demodex number per cm² was 3.9 ± 5.0, while average post-therapy demodex number per cm² was 2.6 ± 4.9 (p = .117). The 577-nm pro-yellow laser caused a change in demodex density. We found that the number of demodex following laser therapy decreased in some patients, while it increased in some others.

Investigation of the Prevalence of Demodex spp. in Dermatological Diseases

OBJECTIVE

An increase in the counts of the Demodex mites that exist in the microbiota of healthy individuals may lead to some dermatological diseases. This study aimed to investigate the prevalence of Demodex spp. among patients diagnosed with acne vulgaris, rosacea, perioral dermatitis, seborrheic dermatitis, eczema, and pityriasis folliculorum and the relationship between the demographic and clinical data of such patients and Demodex.

METHODS

This study included 144 patients (70 with acne vulgaris, 6 with pityriasis folliculorum, 15 with seborrheic dermatitis, 39 with rosacea, 8 with eczema, and 6 with perioral dermatitis) and 73 healthy subjects. We evaluated Demodex positivity using the standard superficial skin biopsy method in all groups. The presence of more than five Demodex mites per square centimeter was considered positive at the diagnosis.

RESULTS

Of the 144 patients included in the study, 107 (74.3%) were female, and 37 (25.7%) were male, while 40 (54.8%) of the 73 healthy subjects were female, and 33 (45.2%) were male. Twenty-one patients (14.5%) and five of the healthy subjects (6.8%) tested positive for Demodex. We found that Demodex positivity rates in the rosacea and acne vulgaris groups were higher than in the control group. However, this level was not statistically significant (p>0.05). We found the highest positivity rate among the patient groups in the pityriasis folliculorum (4/6, 66.7%), rosacea (8/39, 20.5%), and perioral dermatitis (1/6, 16.7%) groups. Lastly, we found no statistically significant relationship between the demographic and clinical characteristics of the groups and Demodex positivity (p>0.05).

CONCLUSION

The present study is the only study that investigated Demodex positivity in six different dermatological diseases. Based on the results, we believe that investigating Demodex spp. positivity in dermatological diseases such as acne vulgaris, rosacea, and pityriasis folliculorum would be beneficial for early diagnosis and treatment.

Steroid Phobia: Is There a Basis? A Review of Topical Steroid Safety, Addiction and Withdrawal

There is a growing concern amongst patients about topical corticosteroid (TCS) side effects, with increasing discussion of topical steroid addiction (TSA) and topical steroid withdrawal (TSW) particularly on social media platforms. However, the acceptance of TSA/TSW as a distinct condition remains controversial within the dermatological community. We conducted a literature search using PubMed, MEDLINE, Cochrane Library, Google Scholar, Embase and Web of Science to identify original articles addressing TSA/TSW. We described the definition and reported clinical features of TSA/TSW including its classification into erythemato-edematous and papulopustular subtype. To assess the validity of TSA/TSW, we summarised and objectively appraised the postulated mechanisms for this condition, including tachyphylaxis, dysregulation of glucocorticoid receptors, rebound vasodilation and impaired skin barrier leading to a cytokine cascade. Understanding the evidence including its limitations and uncertainties highlights areas for future research and helps medical practitioners better counsel and provide care to patients who may be experiencing or who have concerns about TSA/TSW.

Localized Demodicosis in a Dog After Fluticasone Propionate Treatment for Chronic Bronchitis

An 11-year-old, castrated male Shetland Sheepdog presented for a 3-week history of localized nonpruritic alopecia and scaling affecting the peri-nasal region. The dog was being managed for several comorbidities, including chronic bronchitis successfully controlled with the chronic administration of inhaled fluticasone propionate. The physical examination was unremarkable aside from erythema, symmetrical alopecia, scaling and follicular casts affecting the peri-nasal region. Deep skin scrapings and histopathological examination from the lesional skin revealed several live demodex mites consistent with Demodex canis. Transcriptome analysis of lesional skin demonstrated significant downregulation of several cytokines involved in the T helper (Th) 2 and Th17 pathway with moderate upregulation of Th1 cytokine IFN-γ and T-cell recruitment chemokine CXCL10. The dog was immediately treated with oral fluralaner. Clinical signs of demodicosis resolved after 8 weeks and a trichogram was negative for live and/or dead demodex mites. The dog has remained on twice-daily administration of inhaled fluticasone and oral fluralaner every 3 months for 15 months without a demodicosis relapse, in addition to medication to manage the dog's comorbidities. To the author's knowledge, this is the first case of localized demodicosis caused by an inhaled glucocorticoid in a dog.

Which factors influence Demodex proliferation? A retrospective pilot study highlighting a possible role of subtle immune variations and sebaceous gland status

Demodex folliculorum and brevis are commensal mites that live in low densities in human pilosebaceous follicles as part of the normal adult microbiota, but that give rise to demodicosis and, possibly, rosacea, when they proliferate excessively. This proliferation is favored by various factors, including age, marked immunosuppression, sebaceous gland hyperplasia, and hypervascularization-related factors. To study possible factors influencing mite proliferation, we explored the effects of different variables on Demodex densities (Dd) in a retrospective study of two groups of subjects selected on the basis of their clinical diagnosis: Demodex+, consisting of subjects with demodicosis or with centro-facial papulopustules suggesting rosacea (n = 844, mean Dd 263.5 ± 8.9 D/cm² ), and Demodex-, consisting of subjects with other facial dermatoses or healthy facial skin (n = 200, mean Dd 2.3 ± 0.4 D/cm² ). Demodex densities were measured using two consecutive standardized skin surface biopsies (SSSB1 [superficial] and SSSB2 [deep]) taken from the same facial site on each subject. In the Demodex+ group: the SSSB1 decreased with age in women (p = 0.004), and the SSSB2 increased with age in men (p = 0.001) (the pattern was similar for SSSB1 + 2, but not statistically significant); Dds were lower in those who had received cortisone (either topically or systemically); 13 subjects (1.5%) had known immunosuppression, 62 (7.3%) had hypothyroidism, and in 20 (3.6% of the women) there was a reported link with pregnancy; 78 of the subjects (9.2%) were part of a pair from the same family or household; when associated bacterial infection was suspected, Staphylococcus epidermidis was often isolated. Our results suggest close interactions between the mite, sebaceous gland size and function, and subtle variations of immune status. Potential factors influencing Demodex proliferation should be further investigated, including hypothyroidism, pregnancy, corticosteroid administration, Staphylococcus epidermidis, contagiousity, and genetic background.

Perioral dermatitis: diagnosis, proposed etiologies and management

Perioral dermatitis is a common cutaneous condition characterized by acneiform facial eruptions often with an eczematous appearance. A granulomatous subtype exists in addition to the classic variant. Whilst topical corticosteroids have been largely implicated in this condition, its etiology is not completely understood. Using the keywords "corticosteroids," "dermatology," "fusobacteria," "perioral dermatitis", and "periorificial dermatitis" we searched the databases PubMed, MEDLINE and EMBASE to find the relevant literature. Only articles in English were chosen. The level of evidence was evaluated and selected according to the highest level working our way downwards using the Oxford Centre of Evidence-Based Medicine 2011 guidance. This systematic review found the strongest evidence to support topical corticosteroid misuse as the principal causative factor in the pathogenesis of perioral dermatitis. In terms of treatment, further research is required to robustly investigate promising treatment options including tetracyclines, topical metronidazole, topical azelaic acid, adapalene gel and oral isotretinoin.

Identification of cutaneous fungi and mites in adult atopic dermatitis: analysis by targeted 18S rRNA amplicon sequencing

BACKGROUND

Atopic dermatitis (AD) patients have an altered skin bacterial community, with an abundance of Staphylococcus aureus associated with flares, highlighting that microbial organisms may be important for disease exacerbation. Despite strong evidence of association between bacterial skin colonisation and AD, very limited knowledge regarding the eukaryotic microbial community, including fungi and ectoparasites, in AD exists. In this study, we compared the skin and nasal eukaryotic microbial community between adult AD patients (n = 55) and non-AD healthy controls (n = 45) using targeted 18S rRNA amplicon sequencing. Analysis was based on the presence or absence of eukaryotic microorganisms.

RESULTS

The cutaneous composition of the eukaryotic microbial community and the alpha-diversity differed significantly between AD patients and non-AD individuals, with increased species richness on AD skin. Alpha-diversity and beta-diversity were similar on lesional and non-lesional skin of patients. The ectoparasite Demodex folliculorum and the yeast Geotrichum candidum were significantly more prevalent on the skin of AD patients. The prevalence of D. folliculorum on lesional skin was greater among patients recently treated with topical corticosteroid. Malassezia was one of the most frequently detected genera at all sites, with M. globosa and M. restricta being the most prevalent. M. restricta was under represented in the anterior nares of AD patients as compared to the non-AD control population.

CONCLUSION

Significant differences in the eukaryotic microbial communities were found between AD patients and non-AD individuals, with the most striking finding being the significantly overrepresentation of D. folliculorum on AD skin. Whether D. folliculorum can contribute to skin inflammation in AD needs further investigation.

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 folliculorum infestations in common facial dermatoses: acne vulgaris, rosacea, seborrheic dermatitis

Background

Demodex mites are found on the skin of many healthy individuals. Demodex mites in high densities are considered to play a pathogenic role.

Objective

To investigate the association between Demodex infestation and the three most common facial dermatoses: acne vulgaris, rosacea and seborrheic dermatitis.

Methods

This prospective, observational case-control study included 127 patients (43 with acne vulgaris, 43 with rosacea and 41 with seborrheic dermatitis) and 77 healthy controls. The presence of demodicosis was evaluated by standardized skin surface biopsy in both the patient and control groups.

Results

In terms of gender and age, no significant difference was found between the patients and controls (p > 0.05). Demodex infestation rates were significantly higher in patients than in controls (p = 0.001). Demodex infestation rates were significantly higher in the rosacea group than acne vulgaris and seborrheic dermatitis groups and controls (p = 0.001; p = 0.024; p = 0.001, respectively). Demodex infestation was found to be significantly higher in the acne vulgaris and seborrheic dermatitis groups than in controls (p = 0.001 and p = 0.001, respectively). No difference was observed between the acne vulgaris and seborrheic dermatitis groups in terms of demodicosis (p = 0.294).

Study limitations

Small sample size is a limitation of the study. The lack of an objective scoring system in the diagnosis of Demodex infestation is another limitation.

Conclusion

The findings of the present study emphasize that acne vulgaris, rosacea and seborrheic dermatitis are significantly associated with Demodex infestation. Standardized skin surface biopsy is a practical tool in the determination of Demodex infestation.

A new superficial needle-scraping method for assessing Demodex density in papulopustular rosacea

BACKGROUND

Standardized skin surface biopsy (SSSB) is often performed to determine the density of Demodex mites in facial papulopustular eruptions.

AIM

We aimed to test the applicability of a new, "superficial needle-scraping" (SNS) method for assessing Demodex density in papulopustular rosacea (PPR).

PATIENTS AND METHODS

Using SNS method, we measured the Demodex density in patients with PPR, also enrolling the patients with acne vulgaris as controls. SNS was performed by gently scraping off 5 small pustules with the convex surface of the tip of an 18# needle for examination. For comparison, SSSB was also performed in patients with PPR. Demodex density was expressed as "mites per 5 pustules" for SNS and as "mites per cm² " for SSSB.

RESULTS

A total of 40 patients with PPR and 35 patients with acne vulgaris were recruited. There were no statistically significant differences in age or sex between the PPR and acne groups. The Demodex density was 5.6 ± 4.2 in the PPR group versus 0.3 ± 1.0 in the acne group (P < .001). The cutoff of "≥3 Demodex mites per 5 pustules" gave a sensitivity of 78% and a specificity of 97%, and the area under the receiver operating characteristic curve was 0.89. Moreover, SNS and SSSB gave mutually concordant results (positive or negative) in half of the patients.

CONCLUSION

Our study suggests that SNS is a simple and convenient method for assessing Demodex density of pustules in PPR and can be a useful alternative or addition to SSSB for evaluation of Demodex-associated facial papulopustular eruptions.

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

BACKGROUND

Facial densities of Demodex mites have been observed to be greater in patients with demodicosis and papulopustular rosacea than in healthy control patients. In patients with erythematotelangiectatic rosacea (ETR), this density has been observed to be similar to or greater than that of healthy controls. Erythema and telangiectasia, characteristics of ETR, are often observed among patients with pityriasis folliculorum, a discreet demodicosis, suggesting a possible link between these conditions.

OBJECTIVES

To compare the facial Demodex densities of patients with clinical ETR and patients with healthy skin, demodicosis, rosacea with papulopustules, and other facial dermatoses.

METHODS

In this retrospective study, we recorded Demodex densities measured using two consecutive standardized skin surface biopsies (SSSB1 and SSSB2) in 23 patients with ETR, 20 healthy control patients, 590 patients with demodicosis, 254 with rosacea with papulopustules and 180 with other facial dermatoses.

RESULTS

Patients with ETR had higher Demodex densities (D cm^-2 ) than did the healthy controls (mean ± SEM; SSSB1: 15·7 ± 6·3 vs. 1·8 ± 1·1 D cm^-2 , P = 0·042; SSSB2: 38·0 ± 13·7 vs. 5·1 ± 2·1 D cm^-2 , P = 0·026) and patients with other dermatoses (SSSB1: 0·4 ± 0·1 D cm^-2 , P = 0·004; SSSB2: 1·3 ± 0·3 D cm^-2 , P = 0·004), but lower densities than patients with demodicosis (SSSB1: 82·7 ± 4·2 D cm^-2 , P = 0·008; SSSB2: 172·2 ± 7·7 D cm^-2 , P = 0·001) or rosacea with papulopustules (SSSB1: 86·6 ± 7·3 D cm^-2 , P = 0·027; SSSB2: 197·0 ± 12·1 D cm^-2 , P = 0·002).

CONCLUSIONS

ETR may be associated with nonvisible Demodex proliferation, possibly corresponding to a subclinical stage of demodicosis. Dermatologists should be aware of this potential association and look for subclinical demodicosis in patients with ETR, so that topical acaricidal treatment can be offered if Demodex density is high.

Head-and-neck dermatitis: Diagnostic difficulties and management pearls

Head-and-neck dermatitis is a variant of atopic dermatitis (AD) often seen in children and is challenging to diagnose, as it frequently overlaps with other eczematous dermatoses. Successful head-and-neck dermatitis (HND) treatment requires identification of common triggers and clinical mimickers, such as airborne dermatitis, periorificial dermatitis, and steroid-induced rosacea. Head-and-neck involvement negatively impacts quality of life and is often harder to treat than other body parts, as long-term topical corticosteroid use carries higher risks for skin atrophy on the face. Heating and flushing associated with HND further exacerbate the itch-and-scratch-cycle and disrupt sleep. We aim to address diagnostic gaps, identify clinical mimickers, and share clinical pearls in managing HND, including cooling pillows, thermal water sprays, rice starch paper facial masks, and tips to minimize food and saliva-induced facial irritation.

The rapid effect of pulsed dye laser on demodex density of facial skin

BACKGROUND

Recently, treatment with acaricides, which is aimed at reducing excessive proliferation of demodex mites, has gained popularity due to its providing a significant improvement in the symptoms of diseases, such as rosacea, seborrhoeic dermatitis, and perioral dermatitis. The effect of IPL on demodex mites was reported in skin biopsy specimens in three patients; however, to the best of our knowledge, no study exists to date, which evaluates the effect of pulsed dye laser (PDL) on demodex density (Dd) in larger patient group. We aim here in to observe the Dd before and after PDL therapy with two different skin biopsy techniques.

MATERIAL AND METHODS

Thirty-one patients diagnosed with rosacea were included in the study who received PDL treatment. Dds which were measured by using both the SSSB (standardized skin surface biopsy) and CTM (cellophane tape method) techniques before and after 3 weeks of PDL therapy were evaluated.

RESULTS AND DISCUSSION

The Dd of patients before PDL treatment was 13.0 (interquartile range (IQR): 5.0-28.0) and after 3 weeks of PDL treatment it was 6.0 (IQR: 3.0-12.0) with SSSB. After PDL treatment, the Dd was significantly lower than pretreatment the Dd (p = 0.002). The present study shows that PDL significantly reduced Dd in facial skin with one session.

Demodex spp. as a possible aetiopathogenic factor of acne and relation with acne severity and type

Introduction

Acne is a very common skin disease in adolescents and young adults, but it also affects adults. However, its aetiology is not yet fully understood. Demodex appears to be associated with multiple skin disorders, but controversy persists. Some reports indicate a connection between acne vulgaris and demodicosis.

Aim

To confirm the association between Demodex infestation and acne vulgaris.

Material and methods

A total of 108 patients were enrolled in the acne group. Acne severity was calculated as GASS and acne type (adolescent and post adolescent) was recorded. An age-sex matched healthy control group comprising 65 individuals were included in the study. Dermatological examinations were performed and an SSSB was used to determine the presence of Demodex.

Results

In our study, Demodex positivity was seen in 46 (42.6%) patients in the acne group and 8 (12.3%) in the control group; this difference was statistically significant (p < 0.001). A multivariate Backward Step-By-Step Logistic Regression analysis identified the most effective factors for acne development such as Demodex positivity (OR = 5.565, 95% CI: 2.384–12.99 and p < 0.001) and age under 25 years (OR = 2.3 and 95% CI: 1.183–4.473 and p = 0.014). Alcohol consumption was related to Demodex positivity (p = 0.019) in post adolescent acne.

Conclusions

Our study is the first one to evaluate acne severity, acne type and the relationship to Demodex prevalence. We suggest that Demodex infestation should be considered when the classical therapies are ineffective especially in cases of post adolescent acne.

The effect of skin moisture, pH, and temperature on the density of Demodex folliculorum and Demodex brevis (Acari: Demodicidae) in students and staff of the Erzincan University, Turkey

BACKGROUND

The aim of this study was to determine the prevalence and density of Demodex folliculorum and Demodex brevis in students and staff of the Erzincan University, Turkey, and to define the influence of age, gender, educational level, and hygiene as well as skin moisture, pH, and temperature on the presence of Demodex mites.

METHODS

Healthy people without apparent facial dermatoses from nine faculties and five vocational schools of the university were included in the study. The measurements for moisture, pH, and temperature were conducted in the cheek region, while samples for mite presence were taken from the same region using the standard superficial skin biopsy technique.

RESULTS

A total of 538 healthy people, 385 students and 153 university staff, were included in the study. Demodex mites were detected in 50.1% of the students (mean 7.1/cm² ) and in 69.3% of the university staff (mean 13.1/cm² ). There were statistical differences between the groups of people who were cleaning their face one, two, three, or more times daily and between those who were using and not using personal towels. There was a borderline significant difference between the different age groups and people with different education levels. The density of mites was higher in those with a skin moisture of less than 50%, with a pH of 5-6.5 and temperature of 24-28 °C, however the differences between the groups with different skin moisture, skin pH, and skin temperature were not statistically significant.

CONCLUSION

Demodex mites are very prevalent in healthy individuals of both sexes, and this should be taken into consideration when epidemiological and clinical studies are conducted with patients having different dermatological ailments.

Demodex Mite Density Determinations by Standardized Skin Surface Biopsy and Direct Microscopic Examination and Their Relations with Clinical Types and Distribution Patterns

Background

Demodicosis is a parasitic skin disease caused by Demodex mites, and the determination of mite density per square centimeter is important to diagnose demodicosis. Standardized skin surface biopsy (SSSB) and direct microscopic examination (DME) are commonly used to determine Demodex mites density (Dd). However, no study has previously compared these two methods with respect to clinical types and distribution patterns of demodicosis.

Objective

The aim of this study was to compare the value of SSSB and DME findings in reference to the clinical types and distribution patterns of demodicosis.

Methods

The medical records of 35 patients diagnosed with demodicosis between December 2011 and June 2015 were retrospectively reviewed. Demodicosis was classified according to four clinical types (pityriasis folliculorum, rosacea type, acne type, and perioral type) and three distribution patterns (diffuse pattern, U-zone pattern, and T-zone pattern). Two samples, one for SSSB and one for DME, were obtained from a lesion of each patient.

Results

In all patients, mean Dd and the proportion with a high Dd (>5D/cm²) by DME (14.5±3.3, 80.0%, respectively) were higher than by SSSB (5.5±1.3, 37.1%, respectively; p<0.01, p=0.02, respectively). In terms of clinical types, for rosacea type, mean Dd and proportion with a high Dd by DME (12.4±3.5, 84.6%, respectively) were significantly greater than those determined by SSSB (3.6±1.2, 23.1%; p=0.04, p=0.04, respectively). In terms of distribution pattern, for the diffuse pattern, mean Dd and the proportion with a high Dd by DME (17.5±3.7, 100%, respectively) were significantly higher than those determined by SSSB (6.0±2.7, 26.7%; p<0.01, p<0.01, respectively).

Conclusion

The results of our study revealed that DME is a more sensitive method for detecting Demodex than SSSB, especially in patients with diffuse pattern and suspected rosacea type. Further research is needed to confirm this finding.

Rosacea: a Clinical Review

Rosacea is a field within dermatology with new insight within immunological research and new treatment-algorithm. Patient education on rosacea and appropriate treatments is an important aspect in helping patients succeed with therapy. Treatment should be tailored to each individual patient, taking into account: symptoms, trigger factors, patients' wishes, most bothersome symptoms, psychological aspect, individual needs. A combination of clinical therapies to treat different symptoms concomitantly may offer the best possible outcomes for the patient. In this review article we describe these aspects.

Neutrophilic sebaceous adenitis with intralobular Demodex mites: a case report and review of the literature

A 61-year-old white man presented with a 1-week history of an asymptomatic erythematous, annular plaque with minimal scale limited to the nasal bridge. Histological examination showed a mixed infiltrate of lymphocytes and neutrophils within sebaceous glands. The clinical and histopathological presentation was consistent with a diagnosis of neutrophilic sebaceous adenitis. Several Demodex brevis mites were present deep within the affected sebaceous lobules. Demodex brevis mites are uncommon inhabitants of sebaceous glands of the nose, presenting more commonly on other body sites. The cause of neutrophilic sebaceous adenitis is unknown, but the presence of D. brevis in affected sebaceous glands in this case suggests a possible association.

Immunology and pathogenesis of canine demodicosis

Demodex mites colonized the hair follicles and sebaceous glands of mammals millions of years ago and have remained relatively unchanged in this protected ecologic niche since then. The host immune system detects and tolerates their presence. Toll-like receptor-2 of keratinocytes has been demonstrated to recognize mite chitin and to elicit an innate immune response. The subsequent acquired immune response is poorly understood at present, but there is experimental and clinical evidence that this is the main mechanism in the control of mite proliferation. A transgenic mouse model (STAT(-/-) /CD28(-/-) ) has demonstrated that the immune response is complex, probably involving both cellular and humoral mechanisms and requiring the role of co-stimulatory molecules (CD28). It is known that a genetic predisposition for developing canine juvenile generalized demodicosis exists; however, the primary defect leading to the disease remains unknown. Once the mite proliferation is advanced, dogs show a phenotype that is similar to the T-cell exhaustion characterized by low interleukin-2 production and high interleukin-10 and transforming growth factor-β production by lymphocytes, as described in other viral and parasitic diseases. Acaricidal treatment (macrocyclic lactones) decreases the antigenic load and reverses T-cell exhaustion, leading to a clinical cure. Although in recent years there have been significant advances in the management and understanding of this important and complex canine disease, more research in areas such as the aetiology of the genetic predisposition and the immune control of the mite populations is clearly needed.

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.

Reflectance confocal microscopy vs. standardized skin surface biopsy for measuring the density of Demodex mites

BACKGROUND

Reflectance confocal microscopy (RCM) has been recently shown to be effective for measuring the Demodex mite density.

OBJECTIVES

To compare and demonstrate the advantages and disadvantages of standardized skin surface biopsy (SSSB) and RCM for measuring the density of Demodex mites.

MATERIALS AND METHODS

Forty-eight patients (30 female, 18 male) and 47 healthy controls (30 female, 17 male) were enrolled in the study. The patients diagnoses were pityriasis folliculorum (n = 40), papulopustulary rosecea (n = 7) and erythema-telengiectatic rosacea (n = 1). The area with the most intense erythema on the right cheek was selected for imaging with RCM (VivaScope 3000) and SSSB.

RESULTS

Forty-two patients demonstrated high Demodex density [(Dd) > 5 mites/cm(2) ] with SSSB (85.7%). RCM identified demodicosis in 48 patients (100%). The mean Dd measured with RCM (409.8 ± 209.2) was significantly higher than SSSB (15.33 ± 18.1) (P < 0.001). In the patients, RCM demonstrated the mean number of mites 40.90 ± 20.9 and 4.11 ± 6.4 in the controls per 10 mm(2) area. The corresponding mean number of 2.63 ± 0.77 mites was detected in the infested follicles per area of view compared to a mean of 0.77 ± 0.98 mites in the infested follicles in the controls (P < 0.001).

CONCLUSION

Reflectance confocal microscopy is a fast, direct and noninvasive method for Demodex-associated diseases and it is superior to SSSB for Demodex mite detection.

Potential role of microorganisms in the pathogenesis of rosacea

Rosacea is a skin condition of abnormal inflammation and vascular dysfunction. The active contribution of a microbial agent in the development or progression of rosacea continues to be debated. Research supports the presence of commensal Demodex folliculorum mites at increased density in the skin and associates Helicobacter pylori infection of the gut with rosacea. Fewer studies implicate Staphylococcus epidermidis, Chlamydophila pneumoniae, and the Demodex-associated bacteria Bacillus oleronius. No research, however, provides a mechanism by which colonization by a microorganism translates to manifestation of the condition. Prevailing and emerging principles in the biology of the microbiome and the pathophysiology of rosacea may help to reconcile these lingering questions. Here the microorganisms implicated in rosacea are reviewed and the reaction of the microbiome to inflammation and to changes in microenvironments and macroenvironments are discussed to explain potential roles for microorganisms in rosacea pathophysiology.

Small Demodex populations colonize most parts of the skin of healthy dogs

BACKGROUND

It is unproven that all dogs harbour Demodex mites in their skin. In fact, several microscopic studies have failed to demonstrate mites in healthy dogs.

HYPOTHESIS/OBJECTIVES

Demodex canis is a normal inhabitant of the skin of most, if not all, dogs. This hypothesis was tested using a sensitive real-time PCR to detect Demodex DNA in the skin of dogs.

ANIMALS

One hundred dogs living in a humane society shelter, 20 privately owned and healthy dogs and eight dogs receiving immunosuppressive or antineoplastic therapy.

METHODS

Hair samples (250-300 hairs with their hair bulbs) were taken from five or 20 skin locations. A real-time PCR that amplifies a 166 bp sequence of the D. canis chitin synthase gene was used.

RESULTS

The percentage of positive dogs increased with the number of sampling points. When a large canine population was sampled at five cutaneous locations, 18% of dogs were positive for Demodex DNA. When 20 skin locations were sampled, all dogs tested positive for mite DNA. Our study indicates that Demodex colonization of the skin is present in all dogs, independent of age, sex, breed or coat. Nevertheless, the population of mites in a healthy dog appears to be small. Demodex DNA was amplified from all 20 cutaneous points investigated, without statistically significant differences.

CONCLUSIONS AND CLINICAL IMPORTANCE

Using a real-time PCR technique, Demodex mites, albeit in very low numbers, were found to be normal inhabitants of haired areas of the skin of healthy dogs.

Evaluation of the efficacy of oral ivermectin in comparison with ivermectin-metronidazole combined therapy in the treatment of ocular and skin lesions of Demodex folliculorum

OBJECTIVE

To evaluate the efficacy of ivermectin and combined ivermectin-metronidazole therapy in the treatment of ocular and skin lesions of Demodex folliculorum.

METHODS

One hundred twenty patients with skin lesions and anterior blepharitis, whose infestation was treatment-resistant and who had a Demodex count >5 mites/cm² for skin lesions or ≥ 3 mites at the root of each eyelash, were recruited. The treatment regimens were ivermectin and ivermectin-metronidazole combined therapy. We enrolled 15 patients from each of four groups for each treatment regimen. Demodex was detected by standardized skin surface biopsy for skin lesions. Three eyelashes from each affected lower eyelid were epilated and examined. The study subjects were followed-up once a week for four visits.

RESULTS

There was a difference in the mite count between the subgroups taking ivermectin and combined therapy during all follow-up visits. At the last visit, in the combined therapy subgroup, 1.7% of patients showed no clinical improvement, 26.7% showed a marked clinical improvement, and 71.6% showed complete remission. In those on the ivermectin regimen, 27 patients had a mite count >5 mites/cm², 21.7% showed no clinical improvement, 33.3% showed a marked improvement, and 45% showed complete remission.

CONCLUSIONS

Combined therapy was superior in decreasing the D. folliculorum count in all groups and in reducing the mite count to the normal level in rosacea and in anterior blepharitis. On the other hand, the two regimens were comparable in reducing the mite count to the normal level in acne and peri-oral dermatitis lesions.

Facial dermatosis associated with Demodex: a case-control study

Demodex has been considered to be related with multiple skin disorders, but controversy persists. In this case-control study, a survey was conducted with 860 dermatosis patients aged 12 to 84 years in Xi'an, China to identify the association between facial dermatosis and Demodex. Amongst the patients, 539 suffered from facial dermatosis and 321 suffered from non-facial dermatosis. Demodex mites were sampled and examined using the skin pressurization method. Multivariate regression analysis was applied to analyze the association between facial dermatosis and Demodex infestation, and to identify the risk factors of Demodex infestation. The results showed that total detection rate of Demodex was 43.0%. Patients aged above 30 years had higher odds of Demodex infestation than those under 30 years. Compared to patients with neutral skin, patients with mixed, oily, or dry skin were more likely to be infested with Demodex (odds ratios (ORs) were 2.5, 2.4, and 1.6, respectively). Moreover, Demodex infestation was found to be statistically associated with rosacea (OR=8.1), steroid-induced dermatitis (OR=2.7), seborrheic dermatitis (OR=2.2), and primary irritation dermatitis (OR=2.1). In particular, ORs calculated from the severe infestation (≥5 mites/cm(2)) rate were significantly higher than those of the total rate. Therefore, we concluded that Demodex is associated with rosacea, steroid-induced dermatitis, seborrheic dermatitis, and primary irritation dermatitis. The rate of severe infestation is found to be more correlated with various dermatosis than the total infestation rate. The risk factors of Demodex infestation, age, and skin types were identified. Our study also suggested that good hygiene practice might reduce the chances of demodicosis and Demodex infestation.

Morphobiometrical and molecular study of two populations of Demodex folliculorum from humans

A morphobiometrical and molecular study of two populations of Demodex folliculorum from humans isolated from different habitats, skin and eyelashes follicles, were carried out. Morphological and biometrical studies revealed two closely related populations with any distinctive characteristics. For molecular study, a 436-bp region of the 16S rDNA gene and a 453-bp region of the cytochrome oxidase I (COI) gene from individual mites of each population considered were sequenced. Intraindividual and interindividual sequence variation was studied in both populations. Our data show that 16S rDNA is not a useful marker to discriminate between populations; however, COI gene sequences can help to identify the two populations considered, which are morphologically very close and difficult to separate by classic methods. These results are in agreement with the morphological and biometrical differences detected between D. folliculorum from eyelashes and human skin. This study appeals for the revision of the taxonomic status of the D. folliculorum populations, as well as for the species included within genus Demodex.

Risk factors and prevalence of Demodex mites in young adults

Demodex mites are ectoparasites often found in follicles of facial skin. Their role in human diseases is under investigation, and a growing number of studies indicated that they contribute to chronic inflammatory conditions of the skin, such as rosacea, blepharitis, otitis externa, alopecia and folliculitis. In our study we tested 96 healthy adults for the presence of Demodex mites. Risk factors influencing presence of mites and skin types of the tested individuals were evaluated. We found Demodex folliculorum or Demodex brevis in 17.7% of the samples, more frequently in males (21.9%) and in older adults (20%). Use of make-up seems to reduce the likelihood of Demodex carriage, while pet ownership, use of shared items and living in close contact with older adults had no significant influence of presence of mites. Demodex positive individuals described their skin to be drier, more prone to erythema, but less for folliculitis compared to Demodex negative subjects.

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.