Prevalence and risk factors to Demodex folliculorum infection in eyelash follicles from a university population of Mexico.

Demodex folliculorum shows a high occurrence in the general population, however, its pathologic relevance is still controversial. In this prospective study, we evaluated the prevalence of D. folliculorum on eyelashes from 8,033 subjects of a university population (including 7,782 students, and 251 academics). Additional information on some risk factors to infection by the mites was evaluated, as well. A prevalence of 1.47% was found, where 118 individuals were positive for D. folliculorum; and, among them, 63 (53.4%) were women and 55 (46.6%) were men. Results showed a negative correlation with the age (r = -0.45), the highest prevalence was found in individuals between 19 and 22 years of age (2.1%, 84 patients). The number of D. folliculorum mites did not differ between the right and left eye; however, the use of cosmetics or facial cream, contact lens, hair removers, were factors present in patients infected with D. folliculorum. Although Demodex prevalence did not increase in line with weight, we found significantly higher prevalence in the 51-60 kg and 71-80 kg weight groups, and a particularly high prevalence in the over 81 kg weight group (2.6%). In conclusion, it was observed that the main population positive to infection consisted of young adults; this is in contrast with the international evidence reporting a high rate of infection in older adults. Besides, our results suggest that items of daily use such as cosmetics, facial cream, eyeliner, glasses, or contact lenses may be some of the main culprits of the infection by D. folliculorum.

Establishing an RNA extraction method from a small number of Demodex mites for transcriptome sequencing.

Demodex is a type of parasitic mite which could cause serious dermatoses in 11 orders of mammals. However, due to the tiny body with thick chitin hard to be ruptured as well as the difficulty in obtaining a large number of mites, the quantity and quality of extracted RNA could hardly satisfied for transcriptome sequencing. This has hampered the research on functional genes and molecular pathogenesis of Demodex for a long time. To solve the problems above, the present study established a new RNA extraction method in combination Azanno method with liquid nitrogen grinding using 16 human and canine Demodex mite samples. The RNA quality detection results of Agilent 2100 Bioanalyzer showed that 8 of 16 RNA samples met the requirements for trace RNA-Seq, with RIN of 5.0-6.5 and RNA quantity of 1.1-16.0 ng. RNA quality was affected by grinding process and parasitic position of Demodex. Enough grinding number (≥2000) in moderate time (≤20 min) was significant for mites' complete rupture and RNA degradation prevention. D. brevis (100%, 3/3) parasitizing in human sebaceous glands had significantly higher RNA qualification rate than D. folliculorum (57.14%, 4/7) parasitizing in human hair follicles. Yet D. canis parasitizing in dog had lower RNA qualification rate (16.67%, 1/6) as mites were embedded in skin tissues and blood clots. It should be pointed out that microplate reader had defects with a lower RNA qualification rate of 6.25% (1/16) unmatched with 2100 Bioanalyzer, reminding that it could be only used as reference in RNA quality evaluation.

Demodex mites in acne rosacea: reflectance confocal microscopic study.

BACKGROUND/OBJECTIVES: Demodex mite density is emphasised in the aetiopathogenesis of acne rosacea. Reflectance confocal microscopy (RCM) has been shown to be a good method for determining demodex mite density. The objective was to determine demodex mite density using RCM in acne rosacea patients and compare them with controls. METHODS: In all, 30 papulopustular rosacea (PPR) and 30 erythematotelangiectatic rosacea (ETR) totally 60 acne rosacea patients and 40 controls, were enrolled in the study. The right cheek was selected for imaging and RCM was used for scanning. Ten images of 1000 × 1000 µm (total 10 mm2 ) area were scanned from adjacent areas. The numbers of follicles, infested follicles and mites were counted. The mean numbers of mites per follicle and infested follicles were calculated and compared in the patients and control groups. RESULTS: The mean number of mites was 44.30 ± 23.22 in PPR, 14.57 ± 15.86 in ETR and 3.55 ± 6.48 in the control group (P < 0.001). The mean number of mites per follicle was 1.77 ± 0.90 in PPR, 0.57 ± 0.63 in ETR and 0.13 ± 0.23 in the control group (P < 0.001). The cut-off for the mean number of mites for determining mite infestation was 0.17 and above. CONCLUSIONS: Demodex mite density was markedly increased in both ETR and PPR patients. It is believed that the presence of demodex mites plays an important role in rosacea aetiopathogenesis. Demodex mite treatment may reduce the severity of the disease and slow its progressive nature.

Demodex Folliculitis of the Scalp: Clinicopathological Study of an Uncommon Entity.

Demodex is a saprophytic mite in humans commonly present in the pilosebaceous units, which has been implicated as a pathogen in several skin conditions. The clinical presentation and histopathology of Demodex folliculitis of the scalp have been described in only a few case reports. This study was performed to further elucidate the clinicopathological features of this entity. We have studied 333 consecutively submitted scalp biopsies performed for hair loss and alopecia. All specimens were completely step-sectioned. Biopsies with Demodex mites were further studied histopathologically, and the patients' clinical files were reviewed. There were 17 biopsies (5.1%) with Demodex in at least 1 pilosebaceous unit. Based on the clinical presentation, histopathology, and response to therapy, Demodex was considered to be nonpathogenic in 13 cases. The remaining 4 cases were characterized by hair loss, scalp erythema, scales, and pustules. There were 2 or more pilosebaceous units with Demodex along mononuclear and/or neutrophilic infiltrates around and in the involved follicles and occasionally granulomas. All 4 cases responded completely to metronidazole therapy. In conclusion, Demodex is infrequently found in scalp biopsies for hair loss and alopecia, and, in most cases, it does not seem to be pathogenic. Occasionally, however, it is associated with folliculitis characterized by hair loss, erythema, scales, and pustules clinically; neutrophilic and/or mononuclear-cell folliculitis with occasional granulomas histopathologically; and a prompt response to anti-Demodex therapy.

Global divergence of the human follicle mite Demodex folliculorum: Persistent associations between host ancestry and mite lineages.

Microscopic mites of the genus Demodex live within the hair follicles of mammals and are ubiquitous symbionts of humans, but little molecular work has been done to understand their genetic diversity or transmission. Here we sampled mite DNA from 70 human hosts of diverse geographic ancestries and analyzed 241 sequences from the mitochondrial genome of the species Demodex folliculorum. Phylogenetic analyses recovered multiple deep lineages including a globally distributed lineage common among hosts of European ancestry and three lineages that primarily include hosts of Asian, African, and Latin American ancestry. To a great extent, the ancestral geography of hosts predicted the lineages of mites found on them; 27% of the total molecular variance segregated according to the regional ancestries of hosts. We found that D. folliculorum populations are stable on an individual over the course of years and that some Asian and African American hosts maintain specific mite lineages over the course of years or generations outside their geographic region of birth or ancestry. D. folliculorum haplotypes were much more likely to be shared within families and between spouses than between unrelated individuals, indicating that transmission requires close contact. Dating analyses indicated that D. folliculorum origins may predate modern humans. Overall, D. folliculorum evolution reflects ancient human population divergences, is consistent with an out-of-Africa dispersal hypothesis, and presents an excellent model system for further understanding the history of human movement.

Demodex sp. as a Potential Cause of the Abandonment of Soft Contact Lenses by Their Existing Users.

Demodex mites may be a potential etiological factor in the development of various eye and skin disorders. The aim of the study was to investigate the presence of Demodex in the hair follicles of eyelashes and their potential influence on abandoning soft contact lenses which had been previously well tolerated by their users. A group of 62 users of contact lenses (28 with emerging discomfort and 34 without discomfort) were examined. There is a need to check the existence of a relationship between D. folliculorum or/and D. brevis infestation and the emergence of intolerance to the presence of soft contact lenses. The removed lashes were examined under light microscopy, applying standard parasitological methods if demodicosis is suspected. A positive result was assumed if at least one adult stage, larva, protonymph/nymph, or egg of D. folliculorum and/or D. brevis was present. A positive correlation was observed between the presence of Demodex and intolerance to contact lenses by their existing users (p < 0.05), and Demodex sp. infections were observed in 92.86% of patients with intolerance to contact lenses. Our results provide further evidence for the pathogenic role played by the mites in the development of eye diseases.

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

BACKGROUND: 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. OBJECTIVES: To use RCM to monitor the density of Demodex mites in patients with rosacea before and after treatment. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Ubiquity and diversity of human-associated Demodex mites.

Demodex mites are a group of hair follicle and sebaceous gland-dwelling species. The species of these mites found on humans are arguably the animals with which we have the most intimate interactions. Yet, their prevalence and diversity have been poorly explored. Here we use a new molecular method to assess the occurrence of Demodex mites on humans. In addition, we use the 18S rRNA gene (18S rDNA) to assess the genetic diversity and evolutionary history of Demodex lineages. Within our samples, 100% of people over 18 years of age appear to host at least one Demodex species, suggesting that Demodex mites may be universal associates of adult humans. A phylogenetic analysis of 18S rDNA reveals intraspecific structure within one of the two named human-associated Demodex species, D. brevis. The D. brevis clade is geographically structured, suggesting that new lineages are likely to be discovered as humans from additional geographic regions are sampled.

Ocular demodicosis.

We present a case of blepharitis with symptoms lasting two years in duration and refractory to a host of prior medical treatments, including antibiotics, corticosteroids, cyclosporine, and baby shampoo. We recognized the clinical presentation as pathogomonic for demodicosis caused by the parasitic mite, demodex folliculorum, confirmed with light microscopy, and treated appropriately with tea tree oil and hygiene measures--achieving full resolution of symptoms. We highlight the presentation, treatment, and underscore demodicosis as an important, under recognized cause of blepharitis.

Demodex.

PURPOSE: Demodex folliculorum and Demodex brevis are ectoparasites with an astounding prevalence of 100% in patients aged 70 years and older. Every person in this age group is estimated to carry a colony of 1000 to 2000 mites. With such a high prevalence, little attention has been paid to the mite among eye care practitioners. We demonstrate a clinical sequence in a set of case reports to identify the mite. The clinical sequence includes a clinical history of blepharitis, dry eyes, and/or ocular allergy; slit lamp examination of cylindrical dandruff; and confirmation using light microscope evaluation of epilated lashes. CASE REPORTS: Patient 1 was a 68-year-old woman who demonstrates associations with dry eyes and diabetes. Patient 2 was a 44-year-old man with uncommonly seen D. brevis present. Patient 3 was a 40-year-old woman with dry eyes and allergy, showing mite tails protruding from base of lashes. Patient 4 was a 60-year-old woman who demonstrates the association with rosacea. Patient 5 was a 53-year-old woman intermittently taking topical steroid and antibiotic combination medications, with an actual mite photographed on the surface. CONCLUSIONS: Following a clinical sequence helps identify Demodex, the underdiagnosed, undertreated, and underappreciated ocular surface disease.

Method to identify Demodex in the eyelash follicle without epilation.

The ubiquitous skin mite Demodex has been implicated as an instigator of anterior blepharitis. To date, overpopulation of the organism has been verified by cilia epilation (Coston or modified Coston method). This monograph describes an alternate technique to isolate Demodex organisms by eyelash rotation within the follicle. Via this method, without epilation, mites are made visible in follicles that may or may not display the cylindrical cuffing characteristic of demodicidosis.

Polarizable elements in scabies infestation: a clue to diagnosis.

The diagnosis of scabies infestation is straightforward in cases where mite parts are largely visible; however, mites are often not captured in a specimen's planes of section. Polariscopic examination is a fast and simple adjunctive diagnostic tool to light microscopy. We describe the unique polariscopic findings in scabies infestation. Two cases of crusted scabies and eight cases of typical scabies were subjected to polariscopic examination. Diagnostic mite parts were visualized in at least one section in all cases. Attached and detached spines as well as scybala (fecal material) are polarizable. Specifically, spines show a polarizable outer sheath with dark central core while scybala show peripherally concentrated, stippled birefringence. Similar stippled birefringence is visible within the gut of some mites whereas significant birefringence is not appreciated in other mite parts. These results suggest that polariscopic examination is a helpful clue in the diagnosis of scabies infestation, especially in cases where the body of the mite is not visualized.

A new Demodecidae species (Acari) from the yellow-necked mouse Apodemus flavicollis (Rodentia: Muridae)-description with data on parasitism.

This paper describes morphological characteristics and the occurrence of Demodex corniculatus n. sp., which was found on Apodemus flavicollis in Poland. The yellow-necked murid mouse is a common European rodent; until now, it was parasitized by a single demodectic mite species, Demodex rosus, which occurs in the oral cavity and esophagus. The new species was found in hair follicles, particularly within hairy regions of the head and genital-anal area. Demodex corniculatus occurred in 33% of the yellow-necked mice examined. The new species is small (adult stages 140 µm in length); characteristic features of these mites are massive supracoxal spines (ca. 5-6 µm long) on the dorsal side of the gnathosoma and palps with thick-set, bifurcated terminal spines. This paper also contains a checklist of demodecids in European and cosmopolitan murids.

[Evidence-based treatment of canine demodicosis]. / Evidenzbasierte Therapie der Demodikose des Hundes.

This article briefly reviews pathogenesis, clinics and diagnosis of canine demodicosis and summarizes treatment options for this disease based on published evidence. The disease is caused by excessive proliferation of Demodex mites in the hair follicles that may be due to genetic factors or immunosuppressive diseases or treatments. The disease is characterized by alopecia, papules, pustules and crusts. Diagnosis is confirmed by detection of several mites in deep skin scrapings or trichograms. Based on published studies, licensed successful treatments for many patients are weekly amitraz rinses in a concentration of 0.05% and (in dogs with mild to moderate clinical signs) weekly spot-ons containing moxidectin. In severe, treatment-resistant cases, daily oral macrocyclic lactones such as milbemycin oxim (1-2 mg/kg), ivermectin or moxidectin (0.3 mg/kg after daily gradual dose increases from 0.05mg/kg) may be used. Doramectin orally or subcutaneously at 0.6 mg/kg has also been reported as successful therapy. Secondary bacterial skin infections are common and should be treated with antimicrobial shampoos and possibly oral antibiotics.

Prevalencia de infección por Demodex folliculorum en pacientes que acuden a consulta general de oftalmología / The prevalence of Demodex folliculorum infection in patients attending a general ophthalmological consultation

Objetivos Determinar la prevalencia de infección por Demodex folliculorum en pacientes que asisten a consulta general de oftalmología, y su asociación con blefaritis. Métodos Estudio descriptivo de prevalencia. En forma aleatoria se seleccionaron 128 sujetos que asistieron al Centro Oftalmológico Virgilio Galvis y se determinó la presencia de Demodex folliculorum en 4 pestañas de cada uno. Resultados La prevalencia de infección por Demodex folliculorum fue 42,1 % (n= 54). Se diagnosticó blefaritis en el 38,3 % de los pacientes (n=49) y el 63,2 % de ellos (n=31) fueron positivos para D. folliculorum. En el grupo sin blefaritis (n=79) solo el 29,2 % de los individuos tenían el ácaro (n=23) (p=0.0003). Además se encontró una mayor cantidad de parásitos en los pacientes con blefaritis (índice de carga parasitaria 12,7 vs 5,1 (p=0.0001). El 25 % (n=32) de los participantes presentaban descamación en forma de cilindros y en estos el 96,9 % tenían el ácaro (n= 31), mientras que en los sujetos que no tenían cilindros (n=96) el ácaro estuvo presente solo en el 24 % (n=23). Conclusiones El Demodex folliculorum es un parásito que se encuentra en personas sin lesiones oculares, pero que es más frecuente y presenta una mayor carga parasitaria en pacientes con blefaritis. Nuestros resultados sugieren la necesidad de investigar la presencia de Demodex folliculorum en todo paciente con blefaritis y especialmente en los casos en que se observe presencia de descamación en forma de cilindros en las pestañas.

Objectives Determining Demodex folliculorum infection prevalence in patients attending general ophthalmological consultation and such infection's association with blepharitis. Methods This was a descriptive study of such prevalence. 128 subjects who attended the Virgilio Galvis Eye Centre were randomly selected and the presence of D. folliculorum was determined in 4 eyelashes taken from each of them. Results D. folliculorum infection prevalence was 42.1 % (n=54); blepharitis was diagnosed in 38.3 % of the patients (n=49) and 63.2 % of them (n=31) were positive for D. folliculorum. Only 29.2 % of the individuals in the group without blepharitis (n=79) had mites (n=23) (p=0.0003). A higher number of parasites was found in patients with blepharitis (12.7 parasitic load index cf 5.1; p=0.0001); 25 % (n=32) of the participants had scaling in the form of cylinders and 96.9 % of these had the mites (n=31), whereas the mite was only present in 24 % (n=23) of subjects who had no cylinder-type scaling (n=96). Conclusions Demodex folliculorum is a parasite found in people without ocular lesions; however, it is more frequent and has a higher parasite burden in patients with blepharitis. Our results suggested the need for investigating the presence of D. folliculorum in all patients suffering from blepharitis, especially in cases where cylinder-type scaling has been observed in their eyelashes.