ABSTRACT
Objective
Despite the existence of studies evaluating the effect of personal hygiene habits on Demodex mites, which are permanent ectoparasites of humans, there is a paucity of research examining the effect of mask use on the prevalence of Demodex mites during the period of the SARS-CoV-2 pandemic. The present study set out to investigate the impact of mask use during the pandemic and personal hygiene habits on the prevalence of Demodex spp.
Methods
Standardized skin surface biopsy were obtained from Marmara University Faculty of Medicine students’ foreheads and cheeks during the pandemic. Two areas were sampled: foreheads and cheeks. A quantity of immersion oil (ranging from one to two drops) was deposited on the sampled slide area. The slide was covered with a coverslip, then a microscope was invetigated (x4, x10 and x40). Infestation was indicated by the presence of five or more Demodex per cm2. Volunteers were asked to complete a questionnaire about their personal hygiene habits. SPSS v.16.0 (IBM Corp., Armonk, NY, USA) software was used to analyse the results.
Results
A total of 104 volunteers, comprising 43 women and 61 men, participated in the study. Demodex spp. was detected in 49.0% (n=51) of the participants, 51.2% (n=22) of women and 47.5% (n=29) of men. Demodex spp. were identified in 46.2% (n=48) of the samples obtained from the cheek and 13.5% (n=14) of the samples obtained from the forehead. It was determined that all participants with mites were using masks. The detection frequency exhibited an upward trend in proportion to the duration of mask change. Demodex spp. was identified in 52.8% of subjects with a documented history of acne, and a significant correlation was observed between the frequency of facial cleansing and the presence of Demodex spp. (p=0.036).
Conclusion
The research indicates that the increase in Demodex spp. in the cheeks of individuals using medical masks during the pandemic is attributable.
INTRODUCTION
Demodex, a permanent ectoparasite in humans, was first detected by Henle in 1841 and described by German dermatologist Gustav Simon in 1842, who demonstrated its ability to exist in pilosebaceous follicles (1). Two distinct types of Demodex folliculorum and Demodex brevis have been identified in human populations. Demodex species are generally found in the face, scalp, hair follicles on the upper chest and sebaceous glands of healthy individuals without any clinical symptoms (2-4). Demodex spp. mites have been commonly found to occur in all age groups with the exception of newborns. In the neonatal period, infestation with the mite occurs through direct contact. However, the mite is less prevalent in newborns and children, likely attributable to reduced sebum production in these age groups. Furthermore, an increase in mite density has been observed with age (5,6). Demodex prevalence has been observed to increase in advanced age and in patients with immunocompromised. It has been established that Demodex spp. density >5/cm2 is associated with pathogenicity (3,5,6).
The symptoms appear as the number of mites in the follicles or glands reaches a certain threshold. Mites also penetrate the tissue in immunosuppression and bacterial superinfection cases (7,8). Lesions on the face cause itching, redness and enlarged blood vessels. During the inflammatory phase, these become papules, blisters and pustules. The presence of mites is crucial for diagnosis (7-9).
Skin lesions, especially those present on the face, are characterised by pruritus, erythema, telangiectasia, papules, blisters, and pimples in the area where the mites are found during the inflammatory period. These lesions are important in clinical and diagnostic studies (10,11). Although infestation is most commonly observed in the facial region (forehead, cheeks, nose, chin, nasolabial region) in humans, cases have also been reported in various other parts of the body, including the neck, scalp, ear, trunk, and genital region (3,12-14).
The number of studies planned to reveal the reasons for this difference in Demodex spp. prevalence and evaluate risk factors such as sociodemographic data, living conditions, hygiene habits, and skin characteristics of the selected population is limited.
During the COVID-19 pandemic, medical masks were widely used for a long time, and it has been reported that this may lead to changes in skin flora (15-18).
The objective of this study was to ascertain the frequency of Demodex infestation in standard superficial skin biopsy (SSSB) samples obtained from Marmara University Faculty of Medicine students. Moreover, the objective was to ascertain the impact of factors such as the use of medical masks and the diverse personal hygiene practices of the students during the course of the pandemic of the novel strain of SARS-CoV-2 on Demodex infestation.
METHODS
This study is a clinical research aiming to determine the prevalence of Demodex spp. infestation in Marmara University Faculty of Medicine students and the personal hygiene habits of these individuals. The study was conducted between September 2021 and June 2022 on volunteers randomly selected among Marmara University Faculty of Medicine students.
Participants were asked to complete an questionnaire that included personal hygiene details such as mask use and face-washing habits. Subsequently, SSSB were obtained from cheek regions covered by the mask and the forehead. The samples were collected by applying a drop of cyanoacrylate to the surface of a slide and then pressing the slide once onto the corresponding facial area. Two distinct samples were collected from each participant: one from the forehead and one from the cheek.
A quantity of immersion oil measuring 1-2 drops was deposited on the surface of the sampled slide, which was then covered with a coverslip. The presence of Demodex spp. was investigated under x4, x10 and x40 magnification lenses on a light microscope. The presence of more than five mites per square centimetre was considered to indicate an infestation.
This study was conducted in accordance with the principles of good clinical practice as set out in the Declaration of Helsinki. The study was approved by the Marmara University Faculty of Medicine Clinical Research Ethics Committee (ethics committee no: 09.2022.315, date: 11.02.2022). Written informed consent was obtained from all participants.
Statistical Analysis
The results obtained from the questionnaire data and the samples obtained from the participants were analysed with the SPSS 16.0 (IBM Corp., Armonk, NY, USA) package programme. The investigation focused on the correlation between the independent variables present within the personal information form and the subsequent findings derived from the samples. The dependent variables, i.e. the sampling site (cheek and forehead) were then compared using the McNemar’s test. P<0.05 was accepted as statistically significant.
RESULTS
The present study comprised a total of 104 participants, including 43 females and 61 males. Demodex infestation was detected in 51 (49.0%) of the 104 participants. The prevalence of infestation in samples collected from male students was 47.5% (n=29), while in female students it was 51.2% (n=22). The distribution of the participants’ survey data and infestation rates is presented in Table 1. The presence of Demodex spp. was determined in 29.8% (n=62) of all samples (n=208), 13.5% (n=14) of forehead samples (n=104) and 46.2% (n=48) of cheek samples (n=104) (p<0.0001). The presence of infestation was determined in 29.8% (n=62) of all samples (n=208). The light microscopy image of the mites is given in Figure 1.
In the course of the research project, 104 volunteers participated. Of these, 19 (18.3%) volunteers confirmed their use of make-up products. Of these, 18 were female and one was male. Of the 85 respondents who provided a negative response to that question, 25 were female and 60 were male. The infestation rate was 47.4% (n=9) in the samples taken from 19 participants who used make-up products, and 49.4% (n=42) in the samples taken from 85 participants who did not use make-up products. No statistically significant results were found (Table 1). An evaluation was conducted to ascertain the correlation between mask usage and the frequency of mask change, as well as the frequency of Demodex infestation. The findings revealed that the majority of participants (n=96) used masks for a duration exceeding four hours, with only eight individuals opting for change intervals of one to four hours. The percentage of infestation in the forehead area was 14.6% (n=14) and in the cheek area was 47.9% (n=46) in the participants whose mask use time was more than 4 hours (n=96). No statistically significant difference was found (p=0.212).
DISCUSSION
The Demodex spp. are characterised by a prevalence of colonisation, particularly in the facial region, a phenomenon attributable to a number of factors. It has been established that D. folliculorum and, albeit less frequently, D. brevis are endemic to humans (1,6). The use of masks has been demonstrated to increase sebum production and to provide a warm and humid environment, thus increasing the frequency and density of Demodex mites (15-18).
In order to explain the differences in the prevalence of Demodex spp., various studies have been conducted to evaluate risk factors such as sociodemographic characteristics, living conditions, hygiene habits, and skin characteristics of the selected population. Karaman et al. (19) investigated the relationship between gender, age, skin type, frequency of skin care, and the prevalence of Demodex spp. in a study involving a total of 300 university students aged 18 to 30. The study reported a prevalence of Demodex spp. of 37%, and no significant association was found between Demodex spp. prevalence and gender, age, skin type, or frequency of skin care (19).
The number of studies examining the relationship between the frequency of Demodex spp. and mask use is quite limited. In one study, the effect of mask type, demographic characteristics, background and face-washing habits of patients on Demodex prevalence was examined. It was reported that the use of masks in individuals without underlying skin disease did not create a suitable microenvironment for Demodex spp. (20). However, studies have been conducted that suggest a link between mask use and the development of various facial diseases, as well as an increased prevalence of Demodex mites (15-18). As stated in the case report, the long-term utilisation of masks has the potential to modify the microenvironment of the skin, thereby increasing the prevalence of Demodex-related atopic dermatitis, seborrheic dermatitis, acne vulgaris and rosacea (15).
In studies examining the distribution of mites in the body, it has been reported that infestation in humans is most commonly seen in areas such as the face, forehead, cheeks, nose, chin and nasolabial region, but they can also exist in various other parts of the body such as the neck, scalp, ears, chest, back, breast, buttocks and genitals (3,12-14). The fact that sebum secretion is more intense in the forehead and nose regions causes the follicles in these regions to enlarge more compared to other regions; this has been reported to cause Demodex spp. to settle in these regions frequently (21). Studies examining the distribution of the presence of Demodex spp. in different regions of the face have yielded different results. In a study by Tilki et al. (22), it was reported that the prevalence of Demodex spp. in samples taken from the cheek region was statistically significantly higher than in the nasolabial and chin regions. In our study, similar to the study of Tilki et al. (22) the infestation rate in the cheek region was found significantly higher.
The global prevalence of mask-wearing has increased significantly since the onset of the pandemic, with individuals facing extended periods of mask-use. It has been hypothesised that this situation may result in alterations to the skin’s microbial flora (15-18).
Different results were obtained in studies investigating the prevalence of Demodex spp. Yazar et al. (23) reported that Demodex spp. were detected in 2.9% of 171 university students with the cellophane-tape method and Kaya et al. (24) reported that Demodex spp. were detected in 2.7% of 347 male students with the same method. On the other hand, Kaplan et al. (25) reported that parasites were detected in 10.07% of 258 university students, Zeytun et al. (26) in 50.1% of university students (n=538), Özdemir et al. (27) in 47.4% of 270 university students with the SBBB method. In the study conducted by Çetinkaya et al. (28) before the COVID pandemic, the prevalence of the parasite was found to be 35.9% (33/92). They reported that parasites were detected in a single region in 48.5% of individuals with parasites, in two different regions in 42.4%, in three different regions in 6.1%, and in four different regions in 3% (28). It was reported that the presence of parasites was statistically significantly lower in those who used facial cleansing products (p<0.05) (28). In our study, the rate of parasites detected in the cheek region was found to be higher than the samples taken from the forehead region. In our study, we found infestation in a single site (forehead=3, cheek=37) in 40 individuals and in two sites in 11 volunteers. In our study, we found Demodex infestation in 51 (49.0 %) of 104 participants in total. Demodex infestation has been reported in the literature at rates ranging from 10% to 75% (22). Erdal and Albayrak (4) reported Demodex infestation in 21 (14.5%) of 144 patients. However, no significant correlation was found between the frequency of mask change and Demodex frequency in our study.
The data obtained from the forehead and cheek regions in the present study indicate a higher existance of Demodex spp. (47.9%) in the forehead and cheek regions of 96 volunteers who frequently changed their masks (4+ hours) compared to 8 volunteers who changed their masks (1-4 hours) frequently. In summary, the frequent change of the mask may have resulted in a reduced quantity of Demodex in the positive samples obtained from the cheek area. Consequently, the regular replacement of masks during the course of the pandemic may have contributed to a reduction in the prevalence of Demodex spp. in humans.
There are studies investigating the relationship between demographic characteristics and parasite prevalence in individuals with Demodex spp. infestation. In a study conducted in medical students in China, Demodex spp. was found in 21.16% of females and 16.05% of males (29). Tilki et al. (22) found the presence of Demodex spp. in 65.5% of men and 60.3% of women in their study investigating the relationship between skin type and characteristics and demographic characteristics of individuals. In our study, Demodex spp. infestation was found to be 47.5% in males and 51.2% in females. In previous studies examining the relationship between age and Demodex spp. presence, it was reported that the presence of parasite increased with increasing age (2,30). However, no significant relationship was found between age and Demodex spp. infestation in our study. It is thought that this may be due to the limited age distribution of the volunteers included in the study.
In the literature, there are different findings and interpretations about the relationship between the frequency of face-washing and the presence of Demodex spp. According to the study conducted by Kahraman et al. (31) it was thought that frequent face-washing may lead to dryness in the skin and may decrease the rate of Demodex spp. in clean skin. Song et al. (32) found that the prevalence of Demodex mites was significantly higher in students who used warm water instead of room temperature water to wash their faces. Yasak Guner et al. (33) reported that there was no significant relationship between the frequency of face-washing and the presence of Demodex spp. in their study (p=0.12). In our study, no statistically significant difference was found between the frequency of face-washing and water temperature and the frequency of Demodex spp. infestation.
The use of make-up products is thought to contribute to the destruction of Demodex mites by mechanically occluding the follicle, preventing the migration and respiration of the parasite, and also by toxic effect since they contain antiseptics such as alcohol (33). In our study, no significant difference was observed between the prevalence of Demodex spp. in participants who did not wear skin make-up compared to participants who wore
make-up.
In a study conducted by Sevgen and Mor (34) it was reported that a higher rate of Demodex spp. was detected in individuals who did not have epilation or laser application. However, according to our findings, a higher rate of parasite presence was detected in the samples taken from volunteers who had epilation-laser application compared to those who did not, but this difference was not found to be statistically significant. In this respect, our study is inconsistent with the results of Sevgen and Mor (34). The main limitation of our study are as follows: failure to differentiate Demodex mites at species level.
CONCLUSION
In our study, it was evaluated that the higher frequency of Demodex spp. infestation in the cheek area may be related to the use of masks, which became widespread during the pandemic period. We think that more long-term studies with a wider participation should be carried out in order to reveal the effect of mask use on the prevalence of Demodex spp. infestation more clearly.
