Density Of Demodex Mites Research Articles

Data on Demodex Ectoparasite Infestation in Patients Attending an Outpatient Clinic in Greece

Demodex mites are acari, common ectoparasites of humans and other mammalian pilosebaceous units. Demodicosis occurs when mites overpopulate the skin, causing several skin disorders. Our aim was to investigate the prevalence of demodicosis in patients with suspicious clinical features, such as cheek redness, itching, and skin sensitivity, who presented at the outpatient clinic of the Andreas Syggros Dermatology Hospital in Greece. We studied 184 individuals aged between 18 and 97 years and analyzed the content of pilosebaceous units by microscopy to determine the density of Demodex mites. Samples were evaluated as positive when Demodex spp. densities equaled or exceeded 5 mites per square cm. Sixty-six percent of the examined subjects were positive for demodicosis. The age distribution was statistically normal (p = 0.2), and the median age was 51.29 years. Seventy percent of the patients were females, and 30% were males, while 64.46% of the demodicosis-positive individuals were females, and 35.54% were males. We observed a rise in the percentage of males as the age of the patients increased. Demodicosis can be a challenging disease because it presents apart from the typical symptoms, with a variety of nonspecific symptoms mimicking other dermatological skin conditions. Therefore, it is important to investigate Demodex spp. in patients who present with common facial dermatological diseases to improve treatment results. Further studies could contribute to a better understanding of the pathogenic role of Demodex mites and how this role is affected by mite density, host sex and age.

Biologic therapy increases Demodex density in psoriasis patients.

Demodex density is known to increase in various immunosuppressive conditions. The relationship between biologic therapy and Demodex density remains unknown. We aimed to investigate whether the density of Demodex mites is higher in psoriasis patients treated with biologic agents compared to treatment-naive or topically treated patients. A cross-sectional study was conducted, comparing psoriasis patients receiving biologic therapy (n = 34) with controls (n = 33). Demodex density was assessed using the standardized skin surface biopsy technique (SSSB). Statistical analysis was performed to compare the densities and prevalence of demodicosis between the two groups. Demodex density was significantly higher in the biologic therapy group compared to the control group on the right cheek (7.29 vs. 0.12/cm2; P = 0.001), left cheek (8.15 vs. 0.24/cm2; P = 0.002), and whole face (average of all four regions: 5.50 vs. 0.80/cm2; P = 0.001). The prevalence of demodicosis was significantly higher in the biologic therapy group on the forehead (35.3% vs. 12.1%; P = 0.043), right cheek (41.2% vs. 0%; P < 0.001), and left cheek (44.1% vs. 0%; P < 0.001). The frequency of cases with demodicosis in at least one localization was higher in the biological therapy group compared to the control group (61.8% vs. 15.2%; P < 0.001). Psoriasis patients receiving biologic therapy had a higher Demodex density and prevalence of demodicosis compared to controls. Biologics may lead to an increase in Demodex density by blocking specific cytokines, such as interleukin-17 and tumor necrosis factor-α, which play a role in immunity against Demodex. Further research is needed to explore the impact of different biological agents on Demodex density.

Prevalence and density of Demodex mites (Acari: Demodecidae) in patients with seborrheic dermatitis

This study was conducted to determine the prevalence and density of Demodex mites in patients with seborrheic dermatitis. The study included 37 patients and 35 healthy controls who were diagnosed with seborrheic dermatitis by clinical examination. The sample materials were taken from the cheek, nasolabial and jaw areas of the participants using the standard superficial skin biopsy method and examined for the presence and number of Demodex mites under light microscopy. Demodex spp. mites were detected in 34 (91.9%) of the patients and in 20 (60%) of the controls. Demodex folliculorum was detected in 34 of 37 patients (mean 15.7/cm2; total 535) and D. brevis (mean 0.6/cm2; 20 total) in six patients. Demodex folliculorum was detected in 20 of 35 healthy controls (mean 2.7/cm2; total 56) and D. brevis (mean 0.5/cm2; total 1) in one of the 35 healthy controls. When patients and controls were compared in terms of Demodex prevalence and density, the differences were statistically significant. In conclusion, Demodex mites are more prevalent in patients with seborrheic dermatitis in Erzincan Province of Turkey. This condition may be related to the amount of sebum in patients with seborrheic dermatitis, however, this issue should be supported by further studies in which sebum levels are measured and ilarger number of patients are involved.

Pre-Treatment and Post-Treatment Demodex Densities in Patients under Immunosuppressive Treatments.

Background and Objectives: Demodex species are common obligatory parasites and normally present in low number in human beings. Immunosuppression was suggested to be associated with increased density of Demodex mites. Systemic glucocorticoids, cyclosporine, methotrexate, and azathioprine are commonly used immunosuppressive agents. We aim to determine the pre- and post-treatment Demodex densities in patients receiving immunosuppressive therapy and compare with those of healthy subjects. Materials and Methods: Demodex density was investigated at the beginning, first, and third months of the immunosuppressive therapy in 45 patients who received methotrexate, cyclosporine, systemic steroid, or azathioprine treatments and in 45 healthy subjects at the same time as the patients. Five standardized skin surface biopsies were taken from cheeks, forehead, nose, and chin of the patients and control group. The presence of five or more parasites in 1 cm2 area was considered as positive. Results: Demodex test was negative at the beginning of the treatment in all patients. Demodex test was positive in one patient in the first and third months of treatment and in three patients only in the third month of treatment. In the control group, Demodex test was determined as positive in just one healthy individual at the beginning, first and third months of the study. When the patient and control groups were evaluated in terms of Demodex number, there was a statistically significant difference in Demodex density in patients treated with immunosuppressive treatment in the first and third months when compared with the control group (p < 0.05). Conclusion: Immunosuppressive treatment might increase the number of Demodex mites and demodicidosis should be kept in mind in patients on immunosuppressive treatment.

Erythematotelangiectatic rosacea and subclinical demodicosis

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.

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

Standardized skin surface biopsy (SSSB) is often performed to determine the density of Demodex mites in facial papulopustular eruptions. We aimed to test the applicability of a new, "superficial needle-scraping" (SNS) method for assessing Demodex density in papulopustular rosacea (PPR). 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. 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. 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.

Dual anti‐inflammatory and anti‐parasitic action of topical ivermectin 1% in papulopustular rosacea

Recently, therapy of rosacea with inflammatory lesions (papulopustular) has improved substantially with the approval of topical ivermectin 1% cream. It is assumed to have a dual mode of action with anti-inflammatory capacities and anti-parasitic effects against Demodex, which however has not yet been demonstrated in vivo. To find scientific rationale for the dual anti-inflammatory and anti-parasitic mode of action of topical ivermectin 1% cream in patients with rosacea. A monocentric pilot study was performed including 20 caucasion patients with moderate to severe rosacea, as assessed by investigator global assessment (IGA score ≥3) and a Demodex density ≥15/cm2 . Patients were treated with topical ivermectin 1% cream once daily (Soolantra® ) for ≥12 weeks. The density of Demodex mites was assessed with skin surface biopsies. Expression of inflammatory and immune markers was evaluated with RT-PCR and by immunofluorescence staining. The mean density of mites was significantly decreased at week 6 and week 12 (P < 0.001). The gene expression levels of IL-8, LL-37, HBD3, TLR4 and TNF-α were downregulated at both time points. Reductions in gene expression were significant for LL-37, HBD3 and TNF-α at both follow-up time points and at week 12 for TLR4 (all P < 0.05). Reduced LL-37 expression (P < 0.05) and IL-8 expression were confirmed on the protein level by immunofluorescence staining. All patients improved clinically, and 16 of 20 patients reached therapeutic success defined as IGA score ≤1. Topical ivermectin 1% cream acts by a dual, anti-inflammatory and anti-parasitic mode of action against rosacea by killing Demodex spp. in vivo, in addition to significantly improving clinical signs and symptoms in the skin.

Two Consecutive Standardized Skin Surface Biopsies: An Improved Sampling Method to Evaluate Demodex Density as a Diagnostic Tool for Rosacea and Demodicosis.

Diagnosing papulopustular rosacea is not always straightforward; no specific diagnostic test is currently available. A high density of Demodex mites is consistently observed in this condition. This retrospective study assesses an improved method for evaluating Demodex density among 1,044 patients presenting to our dermatology practice. The skin was cleaned with ether and Demodex densities were measured in 2 consecutive standardized skin surface biopsies taken from the same site. Mean densities in patients with rosacea and demodicosis were much higher than those in healthy controls and patients with other facial dermatoses. The optimal cut-off values for the 2 biopsies were combined and the resultant criterion (presence of a first biopsy density < 5 Demodex/cm2 or a second biopsy density < 10 Demodex/cm2) enabled confirmation of a diagnosis of rosacea or demodicosis with a sensitivity of 98.7% and specificity of 95.5%, making this a valuable diagnostic tool for dermatologists in routine clinical practice.

Reflectance confocal microscopy for monitoring the density of Demodex mites in patients with rosacea before and after treatment.

Demodex mites seem to serve as a pathogenic trigger in many Demodex-associated diseases such as rosacea. In facial skin of patients with rosacea significantly higher numbers of Demodex mites have been shown compared with healthy controls. Reflectance confocal microscopy (RCM) allows the detection and quantification of Demodex mites in vivo noninvasively. It is hypothesized that a reduction of Demodex mites under rosacea therapy can be monitored by RCM. To use RCM to monitor the density of Demodex mites in patients with rosacea before and after treatment. In 25 patients with facial rosacea RCM was performed before and after therapy. Mosaics of 5 × 5 mm(2) and 8 × 8 mm(2) were scanned, and the total numbers of mites per follicle and per area were counted, along with the number of follicles per area. In all patients Demodex folliculorum could be detected and quantified using RCM. RCM showed significant differences pre- and post-treatment (P = 0.0053 for 5 × 5 mm(2) and P < 0.001 for 8 × 8 mm(2)). The mean numbers of mites per follicle were 0.63 (range 0.16-2.28) per 8 × 8 mm(2) area and 0.70 (range 0.11-2.20) per 5 × 5 mm(2) area before treatment, and 0.41 (range 0.074-1.75) and 0.51 (range 0.094-1.70), respectively, after treatment. The corresponding mean numbers of mites were 155 (range 45-446) and 86.2 (range 12-286), respectively, before treatment and 96.2 (range 18-363) and 58.5 (range 12-230), respectively, after treatment. By RCM, a reduction in the density of Demodex mites in facial skin of patients with rosacea under therapy, correlating to clinical improvement, can be quantified and monitored noninvasively. Possible reasons for this therapeutic effect are discussed.

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

Reflectance confocal microscopy (RCM) has been recently shown to be effective for measuring the Demodex mite density. To compare and demonstrate the advantages and disadvantages of standardized skin surface biopsy (SSSB) and RCM for measuring the density of Demodex mites. 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. Forty-two patients demonstrated high Demodex density [(Dd)>5mites/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 10mm(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). 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 Demodex mites and bacteria in the induction of rosacea

Rosacea is a common dermatological condition that predominantly affects the central regions of the face. Rosacea affects up to 3 % of the world's population and a number of subtypes are recognized. Rosacea can be treated with a variety of antibiotics (e.g. tetracycline or metronidazole) yet no role for bacteria or microbes in its aetiology has been conclusively established. The density of Demodex mites in the skin of rosacea patients is higher than in controls, suggesting a possible role for these mites in the induction of this condition. In addition, Bacillus oleronius, known to be sensitive to the antibiotics used to treat rosacea, has been isolated from a Demodex mite from a patient with papulopustular rosacea and a potential role for this bacterium in the induction of rosacea has been proposed. Staphylococcus epidermidis has been isolated predominantly from the pustules of rosacea patients but not from unaffected skin and may be transported around the face by Demodex mites. These findings raise the possibility that rosacea is fundamentally a bacterial disease resulting from the over-proliferation of Demodex mites living in skin damaged as a result of adverse weathering, age or the production of sebum with an altered fatty acid content. This review surveys the literature relating to the role of Demodex mites and their associated bacteria in the induction and persistence of rosacea and highlights possible therapeutic options.

Demodex-AssociatedBacillusProteins Induce an Aberrant Wound Healing Response in a Corneal Epithelial Cell Line: Possible Implications for Corneal Ulcer Formation in Ocular Rosacea

The aim of the work presented here was to establish the response of a corneal epithelial cell line (hTCEpi) to protein extracted from a bacterium (Bacillus oleronius) previously isolated from a Demodex mite from a rosacea patient. The response of the corneal epithelial cell line to Bacillus proteins was measured in terms of alterations in cell migration and invasiveness. Changes in the expression of metalloproteinase genes and proteins were also assessed. The results indicated increased cell migration (14.5-fold, P = 0.001) as measured using 8-μm PET inserts (BD Falcon) in a transwell assay and invasiveness (1.7-fold, P = 0.003) as measured using 8-μm Matrigel (BD Biocoat) invasion inserts in a 24-well plate assay format, following exposure to the Bacillus proteins. Cells exposed to the Bacillus protein showed a dose-dependent increase in expression of genes coding for matrix metalloprotease (MMP)-3 (61-fold) and MPP-9 (301-fold). This dose-dependent increase in gene expression was also reflected in elevated levels of MMP-9 protein (1.34-fold, P = 0.033) and increased matrix metalloprotease activity (1.96-fold, P = 0.043) being present in the culture supernatant. Cells also displayed reduced levels of β-integrin (1.25-fold, P = 0.01), indicative of increased motility and elevated levels of vinculin (2.7-fold, P = 0.0009), suggesting altered motility. The results indicate that exposure of corneal epithelial cells to Bacillus proteins results in an aberrant wound healing response as visualized using a scratch wound assay. These results suggest a possible link between the high density of Demodex mites on the eyelashes of ocular rosacea patients and the development of corneal ulcers.

Demodex-associated bacterial proteins induce neutrophil activation

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. To examine the response of neutrophils to proteins derived from a bacterium isolated from a Demodex mite. 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. 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. 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.

Demodex folliculorum in patients with rheumatoid arthritis

AbstractThe objective of this study was to investigate the incidence and density of Demodex folliculorum in the patients with rheumatoid arthritis (RA). Forty-one patients with RA and twenty-seven age and sex matched healthy controls were enrolled in this study. Disease Activity Score (DAS 28) was used for the assessment of disease activity. Out of 41 patients, 33 were females and 8 males. The mean disease duration was 10.9 ± 8.2 years. The mean DAS 28 was 3.8 ± 1.2. No statistically significant differences in the incidence and density of Demodex mites were found between patients with RA and controls. Although immunosuppression is thought to be a risk factor for the D. folliculorum infestation no such correlations could be found in the 41 immunosuppressed patients with RA, therefore, further studies with larger groups are needed.

High incidence of demodicidosis in eyelid basal cell carcinomas.

Although UV radiation is the major cause of basal cell carcinoma (BCC), local factors, such as chronic trauma, irritation, or inflammation, may also have some role in its etiopathogenesis. The pilosebaceous follicle mites, Demodex folliculorum and D. brevis, inhabit most commonly and densely certain facial skin areas, including the nose and periorbital regions, where BCC also develops most frequently. To investigate, in a retrospective histopathologic study, whether a possible etiopathogenetic relationship exists between demodicidosis and eyelid BCCs. We examined 32 eyelid BCC specimens that contained at least five eyelashes or five hair follicles with respect to the presence and density of Demodex mites. As controls, we evaluated 34 matched specimens consisting of benign eyelid skin lesions. Twenty-one of 32 BCC cases (65.6%) and eight of 34 control cases (23.33%) had demodicidosis. Mean mite counts were 1.31 +/- 1.57 and 0.47 +/- 0.99 in BCC cases and controls, respectively. The differences were significant for both prevalence (P < 0.001) and density (P = 0.0052). Although there was a significant positive correlation between increasing mite number and patient age in the control group (r = 0.47, P < 0.05), no significant correlation was found between these two factors in BCC cases (r = -0.102, P > 0.05). Demodicidosis may be one of the triggering factors of carcinogenesis in eyelid BCCs in otherwise predisposed people due to its traumatic/irritating effect or chronic inflammation.

The Demodex mite population in rosacea

The cause of rosacea is unknown; among other factors a causative role has been postulated for the hair follicle mites Demodex folliculorum and Demodex brevis. Our purpose was to compare the population density of Demodex mites in facial skin of defined categories of patients with rosacea with control subjects. We also assessed the impact of tetracycline therapy on the mite population. The population density and distribution of Demodex mites were studied in the facial skin of 42 patients with rosacea and 42 age- and sex-matched control subjects. Mites were counted in measured skin surface biopsy specimens obtained from six standard facial sites with cyanoacrylate glue. The mean mite count was 49.8 (range 2 to 158) in patients with rosacea and 10.8 (range up to 97) in control subjects (p < 0.001); the highest density of mites was found on the cheeks. A statistically significant increase in mites was found in all subgroups of rosacea, being most marked in those with steroid-induced rosacea. Mite counts in patients with rosacea before and after a 1-month course of oral tetracycline showed no significant difference. Increased mites may play a part in the pathogenesis of rosacea by provoking inflammatory or allergic reactions, by mechanical blockage of follicles, or by acting as vectors for microorganisms.