Prevalence of Demodex folliculorum and Demodex brevis in childhood malnutrition and malignancy

Evaluation of the relationship between Demodex infestation and obesity in rosacea patients

BACKGROUND

The changes in the skin caused by obesity may predispose patients with rosacea to Demodex infestation (DI). Besides, identifying predisposing factors in these patients is important for initial treatment plan.

AIMS

The main purpose of this study is to determine the relationship between DI and obesity in patients with rosacea.

METHODS

Sociodemographic characteristics, body mass index, and clinical features of 130 rosacea patients were recorded. Demodex density was measured by noninvasive standard skin biopsy, and a determination of ≥5/cm2 mites was regarded as positive for DI. Patients with a BMI of 30 and above were categorized as the obese group, and those with a BMI below 30 were classified as the nonobese group. Moreover, patients were divided according to DI into positive and negative. These groups were compared with each other.

RESULTS

Upon comparing the patients with and without obesity, it was noted that the obese patients had significantly higher rates of erythematotelangiectatic type rosacea, rosacea severity, and flushing complaints. Furthermore, results show that the DI was significantly more common in obese patients. The most determinant factors for predicting DI in rosacea patients were papulopustular type rosacea, obesity, and rosacea severity, respectively.

CONCLUSIONS

In this study, DI was found to be more common in obese patients with rosacea. Besides, obesity was found to be one of the most determining factors in detecting DI in patients with rosacea.

High Prevalence of Demodex Infestation is Associated With Poor Blood Glucose Control in Type 2 Diabetes Mellitus: A Cross-Sectional Study in the Guangzhou Diabetic Eye Study

PURPOSE

The aim of this study was to investigate the association between type 2 diabetes mellitus (T2DM) and ocular Demodex mite infection.

METHOD

About 381 patients with T2DM from nearby communities were enrolled, and 163 age-matched and sex-matched nondiabetic patients from the cataract clinic were included as the control group. All subjects underwent personal history and demographic data collection, ocular examination, and lash sampling, followed by microscopic identification and counting of Demodex mites. Binocular fundus photography was performed for diabetic patients. Statistical correlation between ocular Demodex infestation and T2DM and blood glucose control status was performed.

RESULTS

The Demodex mite infestation rate (62.5% vs. 44.8%, P < 0.001) and count [3 (0-12) vs. 2 (0-9.6), P = 0.01], especially of Demodex brevis (18.9% vs. 4.9%, P < 0.001) [0 (0-1) vs. 0 (0-0), P < 0.001], were significantly higher in the T2DM patient group than that in the control group. The ratio of Demodex brevis to Demodex folliculorum in the T2DM patient group was significantly higher than that in the control group (1:3 vs. 1:9, P < 0.001). Diabetic patients presented with more cylindrical dandruff (55.1% vs. 39.3%, P = 0.001). Ocular Demodex infestation was strongly associated with poor blood glucose control (HbA 1 c > 7%) (odds ratio = 1.82; 95% confidence interval, 1.12-2.94; P = 0.2) and female sex (odds ratio = 1.69, 95% confidence interval, 1.08-2.65, P = 0.02). No association was found between Demodex infestation and the severity of diabetic retinopathy.

CONCLUSIONS

Patients with T2DM, especially those with poor blood glucose control, tend to have a higher prevalence of ocular Demodex infestation, suggesting that high blood glucose is a risk factor for demodicosis .

Demodicosis in Different Age Groups and Alternative Treatment Options-A Review

Infestation with Demodex mites is a common occurrence, especially in adults and the elderly. More recent attention has been paid to the presence of Demodex spp. mites in children, even ones without comorbidities. It causes both dermatological and ophthalmological problems. The presence of Demodex spp. is often asymptomatic, thus it is suggested to include parasitological investigation tests in dermatological diagnostics, in addition to bacteriological analysis. Literature reports show that Demodex spp. are related to the pathogenesis of numerous dermatoses, including rosacea or demodicosis gravis, and common eye pathologies reported by patients such as dry eye syndrome or ocular surface inflammatory conditions, such as blepharitis, chalazia, Meibomian gland dysfunction, and keratitis. Treatment of patients is a challenge and is usually prolonged, therefore it is important to carefully diagnose and properly select the therapy regimen for the treatment to be successful, and with minimal side effects, especially for young patients. Apart from the use of essential oils, research is ongoing for new alternative preparations active against Demodex sp. Our review was focused on the analysis of the current literature data on the available agents in the treatment of demodicosis in adults and children.

Could there be an association between Hashimoto's thyroiditis and demodex infestation?

BACKGROUND

Human demodex mites are parasites that live in the pilosebaceous unit and can result in the disease demodicosis. While demodicosis may occur as a primary skin disease; immunosuppression, and topical or systemic immunosuppressive treatments can cause secondary demodicosis. It is known that thyroid hormones may cause skin changes, such as xerosis, and thereby may also modulate immune responses in the skin.

OBJECTIVES

The aim of this study is to investigate whether or not that the changes occurring in the skin of patients with Hashimoto's Thyroiditis (HT) predispose to demodex infestation.

METHODS

Seventy-eight patients being followed for a diagnosis of HT at Kocaeli University Endocrinology Outpatient Clinic, between January 2019 and March 2020, constituted the patient group. The control group consisted of 41 patients who did not have any chronic systemic or dermatological disease and were shown to have no thyroid disease by laboratory tests. Demodex intensity in the malar regions of the patient and control groups was determined using the standardized skin surface biopsy (SSSB) method and compared with each other.

RESULTS

HT patients were significantly more likely to have increased demodex density and suggestive SSSB results than the controls (p<0.001, p=0.012, respectively). A significant correlation was found between demodex intensity and the findings of xerosis (p=0.010, p=0.011) and spiny follicular papules (p=0.008, p=0.008) in the patient or control groups, respectively. However, a significant correlation was identified between the demodex density and the symptoms of burning-stinging (p=0.028), and feelings of dryness (p=0.018) roughness (p=0.028) only in the control group.

CONSLUSION

Xerotic skin and/or impaired immune responses as a result of autoimmune changes in patients with HT may lead to secondary demodicosis.

Update on the Management and Treatment of Demodex Blepharitis

ABSTRACT

Demodex blepharitis is a common ophthalmologic disease that is often overlooked in the workup of blepharitis. Demodex infestation occurs in both symptomatic and asymptomatic individuals at similar rates; consequently, its role in the development of blepharitis has not been well elucidated. Two species have been confirmed to inhabit the human eyelid-Demodex folliculorum and Demodex brevis. These species differ in their preferred location of infestation, with D. folliculorum occupying the base of the eyelash and D. brevis inhabiting the meibomian glands, contributing to anterior and posterior Demodex blepharitis, respectively. A clinical index of suspicion must be developed from the history when blepharitis, conjunctivitis, or keratitis in adults and blepharoconjunctivitis or chalazia in children are resistant to treatment. The diagnosis can be strongly suspected by the presence of cylindrical dandruff at the base of the eyelash and confirmed by light microscopy of an epilated lash or by in vivo confocal microscopy. No cure is currently available. Management most frequently includes topical tea tree oil and its active ingredient terpinen-4-ol, both of which have produced good clinical outcomes. Topical tea tree oil is typically applied by a professional due to risk of toxicity. Several second-line treatment options have been studied, including ivermectin, metronidazole, selenium sulfide, microblepharoexfoliation, and lid hygiene. Novel, targeted therapies such as TP-03 (Tarsus Pharmaceuticals) are also currently being investigated in phase 2b/3 clinical trials. The purpose of this review purpose is to characterize Demodex blepharitis in detail, including its historical perspective and various classifications, and describe the latest diagnostic and management strategies.

Clinical characteristics of Demodex-associated recurrent hordeola: an observational, comparative study

Our study evaluated the association between Demodex infestation and recurrent hordeola and examined the clinical features associated with these eyelid lesions. This was an observational, comparative study. We reviewed 250 patients and divided them into the recurrent hordeolum (n = 153) and control (n = 97) groups. Demodex infestation was detected by epilating eyelashes around the lesion/s and viewing them under a light microscope. Patient medical records and photographs were retrospectively analyzed to identify the clinical characteristics of Demodex-associated recurrent hordeola. Demodex was detected in 91 (59.5%) and 17 (17.5%) patients in the recurrent hordeolum and control groups (p < 0.001), respectively. In the recurrent hordeolum group, Demodex mites were found in 74 (68.5%) and 17 (37.8%) of the adult and pediatric patients (p < 0.001), respectively. Among patients with recurrent hordeola, patients in their 20s were most likely to have concomitant Demodex infestation. Patients with Demodex infestations were also more likely to develop recurrent lesions within a shorter period of time from the primary incision and curettage. The most common presentation of Demodex-associated recurrent lesions was external hordeola (67%) (p = 0.002). Demodex infestation may cause recurrent hordeola in adults and children. These mites may play a greater role in the development of lesions in adult patients. The strongest association between Demodex infestation and recurrent lesions was seen in patients in their 20s. Our results suggest that if the hordeola recur within a short period of time with the clinical characteristics of external location of eyelid, multiple numbers of lesions, or anterior blepharitis, eyelash epilation should be performed to identify the presence of Demodex mites.

Comparison of the efficacy of tea tree (Melaleuca alternifolia) oil with other current pharmacological management in human demodicosis: A Systematic Review

Various treatments are found to be moderately effective in managing Demodex-related diseases except tea tree oil (TTO) and terpinen-4-ol (T4O), which showed superior miticidal and anti-inflammatory effects in numerous clinical studies. Their possible effects include lowering mite counts, relieving Demodex-related symptoms, and modulating the immune system. This review summarizes the current clinical topical and oral treatments in human demodicosis, their possible mechanisms of action, side-effects and resistance in treating this condition. TTO (especially T4O) is found to be the most effective followed by metronidazole, ivermectin and permethrin in managing the disease. This is because TTO has anti-parasitic, anti-bacterial, anti-fungal, anti-inflammatory and wound-healing effects. Furthermore, nanoTTO can even release its contents into fungus and Pseudomonas biofilms. Combinations of different treatments are occasionally needed for refractory cases, especially for individuals with underlying genetic predisposal or are immuno-compromised. Although the current treatments show efficacy in controlling the Demodex mite population and the related symptoms, further research needs to be focused on the efficacy and drug delivery technology in order to develop alternative treatments with better side-effects profiles, less toxicity, lower risk of resistance and are more cost-effective.

The Pathogenic Role of Demodex Mites in Rosacea: A Potential Therapeutic Target Already in Erythematotelangiectatic Rosacea?

Rosacea is a common facial dermatosis but its definition and classification are still unclear, especially in terms of its links with demodicosis. Triggers of rosacea (ultraviolet light, heat, spicy foods, alcohol, stress, microbes) are currently considered to induce a cascading innate and then adaptive immune response that gets out of control. Recent histological and biochemical studies support the concept that this inflammatory response is a continuum, already present from the onset of the disease, even when no clinical signs of inflammation are visible. The Demodex mite is beginning to be accepted as one of the triggers of this inflammatory cascade, and its proliferation as a marker of rosacea; moreover, the papulopustules of rosacea can be effectively treated with topical acaricidal agents. Demodex proliferation appears to be a continuum process in rosacea, and may not be clinically visible at the onset of the disease. Molecular studies suggest that Demodex may induce tolerogenic dendritic cells and collaborate with vascular endothelial growth factor (VEGF) to induce T cell exhaustion and favor its own proliferation. These interactions among VEGF, Demodex, and immunity need to be explored further and the nosology of rosacea adapted accordingly. However, treating early rosacea, with only clinically visible vascular symptoms, with an acaricide may decrease early inflammation, limit potential flare-ups following laser treatment, and prevent the ultimate development of the papulopustules of rosacea. The effectiveness of this approach needs to be confirmed by prospective controlled clinical trials with long-term follow-up. Currently, the evidence suggests that patients with only vascular symptoms of rosacea should be carefully examined for the presence of follicular scales as signs of Demodex overgrowth or pityriasis folliculorum so that these patients, at least, can be treated early with an acaricidal cream.

The Biodiversity of Demodecid Mites (Acariformes: Prostigmata), Specific Parasites of Mammals with a Global Checklist and a New Finding for Demodex sciurinus

Demodecidae are the most specialized parasitic mites of mammals; they typically inhabit the skin, but they have been found in other tissues and organs. They can cause demodecosis (a disease which is hazardous and difficult to cure) in humans, domestic animals and livestock. They are parasites with high host and topical specificity. They have been found for most orders of mammals, and they are common in the populations of numerous host species. Therefore, they not only constitute an important subject of veterinary and medical study, but also comprise an excellent model for faunistic and parasitological analyses concerning different aspects of functioning and evolution of the host–parasite relationship. The current level or knowledge of demodecid mites is irregular and fragmentary, and numerous questions require elaboration and ordering, from the taxonomic diversity to geographic distribution and relations with hosts. Such data may be of use i.a. for the development of more efficient and reliable diagnostic methods, as well as understanding the etiology and pathogenesis mechanisms of demodecosis, currently a contentious issue. The present paper lists all formally-described valid species of demodecid mites, together with other functioning specific names, verified and with comments on their status. This is significant for correct species identification and demodecosis diagnostics. The list has been drawn up on the basis of data acquired in the period 1842−2020. It contains 122 valid species of parasite, including their hosts and geographic distribution, data on parasitism, as well as only the second record of Demodex sciurinus in Eurasian red squirrel Sciurus vulgaris in over 100 years since its initial discovery.

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.

Occurrence of Demodex species in patients with blepharitis and in healthy individuals: a 10-year observational study

PURPOSE

Two Demodex species (eyelash mites)-D. folliculorum and D brevis-are believed to be associated with human skin and eye diseases. However, the clinical significance of infection with Demodex species remains controversial.

STUDY DESIGN

The aim of this study was to estimate the prevalence of ocular demodicosis in patients with blepharitis as compared with the prevalence in the healthy population in Poland.

METHODS

This case-control prospective study was carried out from 2007 to 2016. The enrolled patients (668) were divided into 2 groups: the study group, comprising 553 patients with blepharitis (349 women and 204 men, aged 17-88 years), and the control group, comprising 115 healthy volunteers without a history of ocular pathologies (78 women and 37 men, aged 17-88 years). A sample of 10 eyelashes was taken aseptically from each eye of the examined person and later studied under a light microscope.

RESULTS

Demodex species were found in 62.4% (345/544) of the patients in the study group and in 24.3% (28/100) of the controls (P = .001, OR = 0.006). The overall prevalence was 55.8% (373/668) in all the examined participants. The presence of Demodex infection increased with age in both groups. No association of Demodex infection with gender was found (119/204 vs 226/349; P > .05, OR 1.086). A high mean number of mites was present more frequently in patients aged older than 50 years and in those who complained especially about itching (P < .05).

CONCLUSION

The prevalence of ocular demodicosis is significantly correlated with blepharitis and increases with age.

Demodex Mite Infections in Ophthalmic Patients on Indonesian Islands: The ICS Humanitarian Aid Report

Objective:

Demodex is the most common external human parasite. It has been suggested that the Demodex infection may be associated with malnutrition, nutritional deficiencies, reduced immunity, and poor hygiene. The patients who benefitted from humanitarian aid in Indonesia, often demonstrated the abovementioned risk factors. The aim of the present report was to assess the prevalence of Demodex infestation in ophthalmic patients in Indonesian.

Patients and methods:

A total of 217 individuals (132 women) with ocular discomfort, who presented to the ophthalmologist in mission points in Indonesia (Bali, Java, and Papua, the province of Indonesia in the New Guinea Island) were checked for the presence of Demodex on their eyelashes and underwent an anthropometric examination.

Results:

The prevalence of ocular demodicosis varies from 71.2% in Bali to 89.2% in Papua. There were no statistically significant differences between the islands, urban or rural areas, or between sexes. A statistically significant difference was found between nutritional status and Demodex infestation (P = 0.0007). Malnourished and overweight patients had odds of being infested with Demodex that were approximately 8 and 3 times higher, respectively, compared with subjects with a normal body mass index.

Conclusions:

Ocular demodicosis is very common in medically underserved areas of Bali, Java, and Papua, where it exceeds the frequency observed in countries of the northern hemisphere. An abnormal nutritional status comprising of both malnutrition and being overweight appears to be a risk factor for Demodex infection. This issue requires further research.

Demodicosis in two patients with a previous history of Langerhans cell histiocytosis

Demodex mites are commensal organisms rarely found in healthy children. Human demodicosis can be classified as a primary or a secondary form. The secondary form in children usually affects severely immunodepressed children. To our knowledge, this is the first report of human demodicosis associated with Langerhans cell histiocytosis. These cases show that this skin disorder can occur months after completing chemotherapy, without recurrence of the systemic disease.

Demodicosis in Pediatric Cancer

Demodicosis is a rare condition that most often occurs in immunocompromised patients. We here describe a boy with T-cell non-Hodgkin lymphoma who developed a facial papulopustular eruption just before finalizing T-cell non-Hodgkin lymphoma treatment. He was treated for several infectious diseases without improvement. Demodicosis was considered and complete resolution was finally reached with topical metronidazole. We conducted a systematic search of all previously described cases of this condition in children with cancer, which showed that almost all demodicosis cases occurred in patients with lymphoreticular malignancies during maintenance chemotherapy. Hence, demodicosis may be seriously considered in antibiotic-resistant facial papulopustular eruptions in this group of patients to prevent delay of adequate treatment.

Prevalence of ocular demodicosis among patients at Tertiary Care Center, Bangkok, Thailand

AIM

To determine the prevalence of ocular demodicosis by both microscopic examination and molecular detection among patients at King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok.

METHODS

One hundred individuals were enrolled in the study and were divided into five age groups. The meibomian gland dysfunction (MGD) score and qualities of cylindrical dandruff (CD) were also determined. Demodex mite infestations of eyelash samples were screened by both microscopic examination and semi-nested polymerase chain reaction (PCR).

RESULTS

The prevalence of ocular demodicosis as determined by microscopic examination was 42% [Demodex folliculorum (D. folliculorum) 41% and Demodex brevis (D. brevis) 1%]. Among patients who had ocular Demodex infestation, 69% have CD and had an average MGD score of 4; in patients without demodicosis, 15.5% had CD and had an average MGD score of 4.12. Prevalence of ocular demodicosis as determined by semi-nested PCR was 79% (D. folliculorum 78% and D. brevis 1%).

CONCLUSION

This is the first report on the prevalence of ocular demodicosis in Thailand. Patients with CD also had Demodex mites present. Semi-nested PCR is better than microscopy for Demodex infestation detection. An extensive survey with more representative samples is required to determine the prevalence in the country.

Localized demodicosis due to Demodex cati on the muzzle of two cats treated with inhalant glucocorticoids

BACKGROUND

Feline demodicosis due to Demodex cati is a rare skin disease often associated with concurrent disease and generalized immunosuppression. Local immunosuppression due to the application of topical immunomodulatory drugs, such as glucocorticoids and tacrolimus, or by tumour cells has been suggested as a potential trigger for development of localized demodicosis in humans and animals.

OBJECTIVES

The goal was to describe two cats with asthma that developed localized demodicosis on the muzzle as a result of chronic therapy with a glucocorticoid administered via dispensing inhaler mask.

RESULTS

In both cats, the muzzle area exposed to the fluticasone-dispensing chamber exhibited patchy alopecia, mild erythema, crusting and scaling. Deep skin scraping revealed D. cati. Discontinuation or reduction of fluticasone and administration of milbemycin resulted in resolution of clinical signs within 2 months in both cats. A negative skin scrape was obtained after 7 months of milbemycin in one of the cats.

CONCLUSIONS AND CLINICAL IMPORTANCE

Demodicosis should be considered as a possible differential diagnosis in cats with primary alopecia or other skin lesions on the face exposed to inhalant glucocorticoids. Minimization of contact between the inhalant glucocorticoid and the skin can be achieved by wiping residual powder from the face and by keeping the mask tightly pressed to the skin to avoid contact with the surrounding area.

Increased density of Demodex folliculorum mites in pregnancies with gestational diabetes

OBJECTIVE

To investigate the presence of Demodex in patients with gestational diabetes and the impact of glucose regulation on Demodex density in gestational diabetes.

SUBJECTS AND METHODS

The study population consisted of 33 patients with gestational diabetes and 30 pregnant women without gestational diabetes (control group). The age, parity, gestational age, and BMI of the study group were recorded and the patients were divided into 2 groups, i.e. those with regulated and unregulated glucose levels, according to their postprandial 1st- and 2nd-hour glucose values. A standardized skin surface biopsy method was used to determine if patients had Demodex folliculorum infestation (>5 mites/cm(2) of skin).

RESULTS

Patients with gestational diabetes had a statistically significantly higher Demodex density compared to the control group (24.2 vs. 3.3%; p < 0.001). Furthermore, a significantly higher proportion of gestational diabetes patients with unregulated glucose levels had a higher Demodex density compared to those in the regulated subgroup (6/19 vs. 2/14; p = 0.001).

CONCLUSION

Our study revealed that the Demodex density was increased in gestational diabetes patients. Further, poor glucose regulation could be the mechanism responsible for the increased Demodex density in gestational diabetes patients with unregulated glucose levels compared to those with regulated glucose levels.