Human Demodicosis Research Articles

Type 2 Diabetes Mellitus and Demodex folliculorum Infestation: A Cross-Sectional Study in Peruvian Patients.

Background. Demodex folliculorum is a mite that causes human demodicosis, which is characterized by producing lesions on the face, and its infestation could be associated with factors that alter the immune response, including Type 2 Diabetes (T2D). This study aimed to evaluate the relationship between T2D and D. folliculorum infestation in patients attended at a hospital in Peru in 2021. Methods. A cross-sectional study enrolling patients who were classified according to the presence (n = 100) and absence (n = 100) of T2D was conducted. Information was obtained on age, sex, domestic animal husbandry, and symptoms and signs associated with demodicosis. Demodicosis was determined to be present when counts of D. folliculorum greater than five mites per cm2 were found in superficial facial skin biopsies. Results. A frequency of demodicosis in 76 and 35 patients with and without T2D, respectively, was observed. In the multivariate analysis adjusted for confounders age, sex, and domestic animal husbandry, T2D was found to be associated with D. folliculorum infestation (PR: 2.13; 95% CI95: 1.42–3.19). Conclusions. T2D was associated with D. folliculorum infestation. In this sense, it is important to strengthen surveillance to identify of D. folliculorum infestation in people with T2D.

The Effectiveness of Topical Tea Tree Oil (Terpinen-4-Ol) in Human Demodicosis: A Literature Review

Demodecosis is a skin disorder caused by parasites with the demodicosis type. The primary cause of this condition in humans is two kinds of Demodex mites, D.folliculorum and D.brevis. Demodicosis are usually treated with TTO, but the effectiveness is not well documented. To evaluate the effects of topical Tea Tree Oil on demodicosis infestation in people. We use the following string in Google Scholar; PubMed; Science Directs with keywords (“Demodicosis”iORi“demodex”iORD.folliculorumiORiiD.Brevis) ANDi (TTOiORiT4OiOR tea tree oil). The articles compatible with the restriction criteria then screened using the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) method. The quality of the articles is tested using GRADE method. A total of 4 of 1949 articles recorded according to the inclusion criteria, all three articles were randomized clinical trials. 351 patients were treated with topical Tea Tree Oil (TTO) scrub with eyelash shampoo, the most common ocular symtomps is ocular dryness. The treatment is provided on a scale 18 to 35 years of age, topical TTO scrub with consentrated persentation 5-50% with eyelash shampoo was at twice-daily treament for 4 weeks. No serious side effect. Topical administration of Tea Tree Oil has shown a reduction in human demodicosis.

A Case Report of Human Demodicosis in a Patient Referred to a Dermatology Clinic in Tabriz, Iran

Background: The genus Demodex belongs to the order Prostigmata and the family Demodecidae that has several species of uncommon mites, some of which cause severe scabies in animals. There are two species of this mite that cause disease in humans, including Demodex folliculorum, which is known as hair follicle mite, and Demodex brevis. This disease is more common in women than in men. Case Presentation: The patient is a 36-year-old woman living in one of the villages of Tabriz city who referred to a dermatologist following severe itching and hyperkeratosis (abundant dandruff) of the cheeks. Then, she was introduced to the laboratory for preparing a slide from a sample taken from the patient’s cheeks. A large number of Demodex mites were observed in the microscopic test of the sample. Conclusion: In patients referred to skin clinics with scaling and itching, especially in the head and face, the complication may be due to Demodex infection. Therefore, it is suggested that demodicosis be considered in differential diagnosis in such patients.

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.

Immune mechanisms in human and canine demodicosis: A review.

Demodex mites are saprophytic parasites of the mammalian skin, mostly found in or near pilosebaceous units of hairy regions. While they can be found in healthy humans and animals without causing any clinical manifestations, they were suggested to create pathogenic symptoms when they appear in high densities under favourable conditions (ie, demodicosis). Nevertheless, their role as the primary causative agent of the pathogenic conditions in humans is debated today. Canine demodicosis, which is highly prevalent in certain dog breeds, provides a valuable tool for studying the pathogenesis of human demodicosis. Canine and human demodicosis are caused by different Demodex species, and the clinical manifestations in former could be life-threatening. Nevertheless, current literature suggests similar immune responses and immune evasion mechanisms in human and canine demodicosis; cellular immunity appeared to have a central role in protection against demodicosis, and Demodex mites were shown to influence both innate and adaptive immune response to escape immune attack. The aim of this review is to summarize the relevant literature on demodicosis obtained from studies conducted on both organisms, and draw the attention to the effect of mite-associated factors (eg, microbiota) on the different clinical manifestations displayed during human and canine demodicosis.

Demodikoz

Demodicosis is the term applied to cutaneous diseases caused by Demodex folliculorum and Demodex brevis. Demodex mites are acquired shortly after birth. They are saprophytic ectoparasites that are found primarily in areas rich in sebaceous glands, like face, scalp, neck. While human demodicosis is a skin disease sui generis, it can mimic many other inflammatory dermatoses. Therefore demodicosis are commonly underdiagnosed, and are masked behind other diagnoses such as papulopustular rosacea, erythemato telangiectasic rosacea, seborrheic dermatitis, perioral dermatitis, contact dermatitis, atopic dermatitis, phyma, seborrhea, etc. Human demodicosis is classified into a primary and secondary form by Chen and Plewig. Absence of pre-existing or concurrent inflammatory dermatosis (acne, rosacea or perioral dermatitis), abnormal increase in mite colonization in active lesions, and remission of the lesions following adequate treatment with topical or systemic acaricides/arachnicides, but not with antibiotics with antiinflammatory effects are diagnostic criteria of primary demodicosis. Secondary demodicosis is defined to skin lesions associated with an abnormal increase of Demodex mites in patients with other known skin or systemic diseases. Clinically, demodicosis has a wide range of variants and may manifest as folliculitis (Pityriasis folliculorum), papulopustular erythema (Rosacea-like demodicosis), blepharoconjunctivitis (demodectic blepharitis), and granulomatous rosacea-like demodicosis (Demodicosis gravis) The pathogenesis of human demodicosis remains largely obscure Here, we discuss the clinical manifestations, pathogenesis of demodicosis, and treatment strategies.

Can the tea tree oil (Australian native plant: Melaleuca alternifolia Cheel) be an alternative treatment for human demodicosis on skin?

Australian tea tree oil (TTO) and its extract terpinen-4-ol (T4O) are found to be effective in moderating demodex-related diseases. Their possible effects are lowering the mite counts, relieving the demodex-related symptoms and modulating the immune system especially the inflammatory response. This review summarizes the topical treatments of TTO and T4O in human demodicosis, their possible mechanism of actions, side-effects and potential resistance in treating this condition. Although current treatments other than TTO and T4O are relatively effective in controlling the demodex mite population and the related symptoms, more research on the efficacy and drug delivery technology is needed in order to assess its potential as an alternative treatment with minimal side-effect profile, low toxicity and low risk of demodex resistance.

Ácaros del género Demodex: ¿parásitos colonizadores de personas sanas o asociados a patología ocular?

Demodex folliculorum and Demodex brevis are mites that are responsible for human demodicosis affecting skin and frequently linked to ocular diseasess. The aim of this work was to determine the association between Demodex sp. and eyelid and eyelash diseases and to establish the predisposing factors for acquiring this parasitic disease. Eyelashes from symptomatic and asymptomatic patients (n=72) between 9 and 82 years old were analyzed, where 53% were positive for Demodex sp., of which 66% manifested ocular symptoms and pathologies, blepharitis and dry eye being prevalent. Significant correlations between Demodex and patients over 60 years of age (p<0.001) and between Demodex sp. and dry eye patients / blepharitis (p<0.001) were observed. We consider that it is necessary to search for Demodex sp. especially in those patients suffering from dry eye and blepharitis and/or during immunosenescence in order to implement specific antiparasitic treatments.

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.

Human demodicosis: revisit and a proposed classification

Human Demodex mites (Demodex folliculorum and Demodex brevis) hold a high rank in the evolutionary and phylogenetic hierarchy of the skin microbiome, although in most people their presence is of no consequence. While human demodicosis is a skin disease sui generis, it can mimic many other inflammatory dermatoses, such as folliculitis, rosacea and perioral dermatitis, leading to unspecific and confusing descriptions in the literature. Here, we propose to classify human demodicosis into a primary form and a secondary form, which is associated mainly with immunosuppression. The clinical manifestations of primary demodicosis may include (i) spinulate demodicosis, currently known as pityriasis folliculorum, involving sebaceous hair follicles without visible inflammation; (ii) papulopustular/nodulocystic or conglobate demodicosis with pronounced inflammation affecting most commonly the perioral and periorbital areas of the face; (iii) ocular demodicosis, inducing chronic blepharitis, chalazia or, less commonly, keratoconjunctivitis; and (iv) auricular demodicosis causing external otitis or myringitis. Secondary demodicosis is usually associated with systemic or local immunosuppression. Treatment is only weakly evidence based, and the most effective concentrations of acaricides remain to be determined. Optimization of an in vitro or ex vivo culture model is necessary for future studies. Endosymbiosis between certain bacteria and Demodex mites in the pathogenesis of demodicosis deserves more attention. Further clinical observations and experiments are needed to prove our hypothesis.

A clinico‐pathological approach to the classification of human demodicosis

Demodicosis is a parasitic skin disease caused by the follicle mites Demodex folliculorum and Demodex brevis. Although there are several clinical variants of this disease, a clear classification is missing. To characterize the clinical features and course of the different forms of demodicosis. Prospective study of 87 patients with clinical symptoms of demodicosis and positive acarological findings. Each patient was examined an average of six times during the treatment period. We suggest that demodicosis be divided into both primary and secondary types. The usual etiological agent of primary demodicosis is D. folliculorum, which causes an erythemato-squamous eruption in the facial T-zone. The rash starts on unaltered skin and covers 8 - 15 % of the face. Pruritus accompanies the onset of the rash, while erythema is first apparent after papulo-pustules are seen and disappears after treatment. Half the patients show seasonal exacerbations. Secondary demodicosis is usually caused by D. brevis and characterized by a symmetrical malar papulo-pustular eruption. It develops on diseased skin and covers 30 - 40 % of the face. Pruritus starts after the lesion exacerbation, but erythema precedes the papulo-pustular phase and persists after treatment. Most patients flare during the summer. The facial distribution, seasonality and pathogenesis, as well as the species of mite involved, must be taken into consideration in separating the various forms of demodicosis.

The Role of HLA A2 and Cw2 in the Pathogenesis of Human Demodicosis

Background: Demodicosis is a chronic skin disease caused by parasitic mites of the genus Demodex. It usually affects the face area causing major esthetical problems. The pathogenesis of demodicosis is not fully understood; however, it is quite apparent that immunological mechanisms mediate its development. Objective: The goal of this study was to study the correlation between immunological and immunogenetic data obtained from patients with demodicosis in order to clarify the pathogenesis of Demodex infestation. Methods: Twenty-five patients with demodicosis and 13 age- and sex-matched healthy subjects participated in the study. The presence of mites was determined by microscopic inspection of sebum gland secretions. The immune response was evaluated by identifying membrane markers of different immune cells using monoclonal antibodies (anti-CD3+, CD4+, CD8+, CD16+, CD20+ and CD95+) while the concentration of IgA, IgM and IgG was measured by simple radial immunodiffusion. The level of circulating immune complexes and total hemolytic complement as well as the preparatory and digestive function of neutrophils and the functional activity of leukocytes were also studied. Patients were typed for HLA A, B, Bw and Cw using the microlymphocytotoxicity method. Results: The comparison between patients with and without the A2 phenotype showed that the latter have lower numbers of CD8+, lower functional activity of leukocytes, higher concentrations of IgA, larger affected skin areas and are more often affected by deep papular and papulopustular forms of demodicosis than those with the A2 phenotype, showing that this allele has a protective role in demodicosis. Patients exhibiting the Cw2 phenotypes were rather susceptible to demodicosis. They showed decreased numbers of CD3+, increased levels of phagocytic activity, higher mite density and severer skin damage as compared to patients lacking Cw2. Conclusions: The HLA A2 and Cw2 phenotypes have an important diagnostic, prognostic and pathogenetic significance and could play a role in resistance or susceptibility to demodicosis by regulating the end phase of the immune response.

Immune response in demodicosis.

Demodex folliculorum and Demodex brevis are obligatory parasites in the hair follicles and in the pilosebaceous glands. Although most people are infested with these mites, only a small number develop the clinical symptoms of demodicosis. The objective of this study was to determine the distinguishing features of the immune response to the infestation of the skin by Demodex mites. Twenty-nine patients with human demodicosis and 13 age- and sex-matched healthy subjects participated in the study. The presence of mites was determined by microscopic inspection of secretion from sebum glands. The immune response was evaluated in the peripheral blood by identifying membrane markers of different immune cells using monoclonal antibodies, while the concentration of immunoglobulin (Ig)A, IgM and IgG was calculated by simple radial immunodiffusion using anti-IgA, anti-IgM and anti-IgG. The level of circulating immune complexes and total haemolytic complement, as well as the preparatory and digestive function of neutrophils, and the functional activity of leucocytes were also studied. The absolute number of CD95+ was higher in patients with demodicosis. The absolute number of CD3+, CD4+, CD8+ and CD16+ cells, the ratio CD3+/CD20+ and the functional activity of leucocytes were significantly lower in individuals infested with Demodex mites. No significant differences were found in the percentage and absolute number of CD20+ cells, the ratio of CD4+/CD8+ T-cell subpopulations, circulating immune complexes, level of serum complement activity (CH(50)), activity and index of phagocytosis and the levels of IgA, IgM and IgG antibodies between individuals infested with Demodex mites and the control group. The readiness of lymphocytes to undergo apoptosis increases in parallel to the increasing density of the mites. This could be the result of local immunosuppression caused by the mites, which allows them to survive in the host skin.

Association between human demodicosis and HLA class I.

Demodex folliculorum and D. brevis are obligatory parasites in hair follicles and in pilosebaceous glands of human skin. Although most people are infested with these mites, only a small number develop the clinical symptoms of skin demodicosis. The objective of this study was to determine the association between HLA specificity and demodicosis. Twenty-five patients with human demodicosis and 150 controls were typed for HLA-A, B, Bw, and Cw using the microlymphocytotoxicity method. The immune response was evaluated by identifying membrane markers of different immune cells using monoclonal antibodies. An association between the frequency of HLA Cw2 and Cw4 haplotypes and human demodicosis was established. The risk of developing clinical symptoms of this disease is 5.0 times higher for people with the Cw2 phenotype and 3.1 times higher for those with the Cw4 haplotype. Individuals who have the HLA A2 phenotype are 2.9 times more resistant to demodicosis. A positive correlation between demodicosis and the haplotypes A3-Cw4, A3-Cw2, A3-B17, A3-B35 and B35-Cw4 was found. In addition, an association between Cw2 and Cw4 alleles in the phenotype of patients with demodicosis and a decrease in the number of natural killer cells was found.

Note on an early record of human demodicosis in China

Abstract A human case of demodicid blepharitis was misidentified as a nematode Thelazia callipaeda, or “eye worm”, infestation by Faust and reported by Howard and Faust in 1927 and 1928 from a Canadian missionary at Huaxi (West China) University, Chengdu, China. The present author shows that all descriptions of the symptoms with the pathological changes from biopsy identified conform to symptoms of demodicid infestation. Presumably the case was a mixed infestation of Demodex folliculorum and D. brevis. This is the earliest actual scientific record of human demodicosis in China, although the patient was not a Chinese national.