Correlation Demodex Folliculorum and Skin Biophysical Parameters

doi:10.4236/jcdsa.2013.33034

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Journal of Cosmetics, Dermatological Sciences and Applications, 2013, 3, 222-227

http://dx.doi.org/10.4236/jcdsa.2013.33034 Published Online September 2013 (http://www.scirp.org/journal/jcdsa)

Correlation Demodex Folliculorum and Skin Biophysical

Parameters

Ts. Sarangua1, A. Gurbadam2, Ya. Enkhtur3*

1Department of Biology and Histology, Health Sciences University of Mongolia, Ulaanbaatar, Mongolia; 2Department of Biology

and Histology, Health Sciences University of Mongolia, Ulaanbaatar, Mongolia; 3Department of Dermatology, Health Sciences Uni-

versity of Mongolia, Ulaanbaatar, Mongolia.

Email: *[email protected]

Received July 25th, 2013; revised August 24th, 2013; accepted August 31st, 2013

which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

ABSTRACT

Purpose: Demodex folliculorum is a transparent mite, 0.3 - 0.4 mm long, which asymptomatically parasitizes the hu-

man pilosebaceous follicles. D. folliculorum is observed in normal skin with a prevalence of 100% and a density of ≤ 5

D/cm2 in the adult population. Materials and Methods: This study evaluated the differences in pH on the five facial

sites between the two populations with and without D. folliculorum. The relationship between pH and skin surface oil

was analyzed in populations with and without Demodex mites. Mongolian 750 subjects (370 males and 380 females)

aged 16 - 84 years, who lived in Ulaanbaatar city, were enrolled in this study. The eligibility criteria included a mini-

mum age of 16 and no physical and dermatologic illness, no cosmetic. Results: Skin surface oil among the five facial

areas differed significantly in both subjects with and without Demodex folliculorum (P < 0.001). When the skin surface

oil on the T-zone, U-zone was compared, those on the T-zone were significantly higher than those of the U-zone (P <

0.001) in both populations (P < 0.01). The pH levels on the five facial sites, and U-zone, T-zone and MFpH differed

significantly in among both subjects with and without Demodex folliculorum (P < 0.001). In both groups, the pH levels

of the U-zone were significantly lower than the pH of the T-zone (P < 0.001). Conclusions: Among the five facial sites

in subjects with Demodex folliculorum, there were significant negative correlations between skin surface oil and pH on

the forehead (p < 0.001, r = 652), cheek (P < 0.001, r = 0.656), nose (P < 0.001, r = 0.754), chin (P < 0.001, r = 0.679),

and T-zone (P < 0.001, r = 0.698), MFSE-MFpH (P < 0.001, r = 0.483). In contrast, among the five sites in subjects

without Demodex folliculorum, a significantly negative correlation between skin surface oil and pH was observed on

the forehead (p < 0.001, r = 766), cheek (P < 0.001, r = 0.798), nose (P < 0.001, r = 0.706), chin (P < 0.001, r = 0.823),

and T-zone (P < 0.001, r = 0.602), U-zone (P < 0.001, r = −0.550).

Keywords: Demodex Folliculorum; Skin Surface Oil; Skin Surface pH; Skin-pH-Meter

1. Introduction

Demodex folliculorum is a transparent mite, 0.3 - 0.4

mm long, which asymptomatically parasitizes the human

pilosebaceous follicles [1]. D. folliculorum is observed in

normal skin with a prevalence of 100% and a density of

≤5 D/cm2 in the adult population [1,2].

Subjects with Demodex folliculorum compared to

subjects without Demodex folliculorum have been well

established by several researchers. Youn et al. proposed

a method to objectively classify facial skin types de-

pending on skin surface oil levels (CL) measured by the

Sebumeter® [3].

Skin surface pH is another noteworthy skin biophysi-

cal parameter to associate with Demodex folliculorum

because the “acid mantle” (acidic skin surface) is thought

to have at least four major important effects on the grow-

th rate of P.acnes, the production rate of exoenzymes and

antigens, the stability of exoenzymes, and enzyme activi-

ty [4-6]. In addition, a correlation between sebum secre-

tion and pH has not been researched in these Mongolian

populations. This study also evaluated the differences in

pH on the five facial sites between the two populations.

Lastly, the relationship between pH and sebum secretion

was analyzed in populations with and without Demodex.

These differences should be further examined in future

studies in Mongolian youth.

*Corresponding author.

Correlation Demodex Folliculorum and Skin Biophysical Parameters 223

2. Materials and Methods

Mongolian subjects who lived Ulan-Bator (Ulan-Bator

city, Mongolia) were asked to participate in the study.

The eligibility criteria included a minimum age of 16 and

no physical and dermatologic illness, as well as no cos-

metic problems. Participants were asked not to wear any

cosmetics and not to wash their face within 30 minute

prior to the measurements. 750 subjects (370 males and

380 females) aged 16 - 84 years were enrolled in this

study. The subjects were divided by age into 11 groups,

i.e., 16 - 21, 22 - 27, 28 - 33, 34 - 39, 40 - 45, 46 - 51, 52 -

57, 58 - 63, 64 - 69, 70 - 75, and 76 - 84 years old

(classification age group divided by age 5 years old, Pro-

visional guidelines on standard international age classi-

fications, United Nations) [7]. This study evaluated the

difference in skin surface pH and skin surface oil on five

facial areas (forehead, nose, chin, right and left cheeks)

in a healthy Mongolian population. The relationship be-

tween skin surface pH and skin surface oil were analyzed

in each of the two groups. All procedures were perfor-

med by the same investigator in a room at a constant

temperature (20˚C) and relative humidity (52%) from

March 2012 until March 2013 to minimize variations

caused by different investigators, temperature, humidity,

and season. The study protocol was approved by the

Human Research and Ethical Committee of Health Sci-

ences University of Mongolia (HSUM). The skin sur-

face oil levels on five different sites of the face: forehead

(mid-glabella), nose tip, chin (mental prominence), right

and left cheeks (the most prominent area of both zygo-

mas) were measured by the Electronic Skin Analyzer®

(PSI Co., Ltd., Korea). Press the Electronic Skin Analy-

ser® sensor smoothly on the skin. Sebum was analyzed

from each site on a plastic strip with a constant pressure

between 0 and 10. Reclassification of the skin surface oil

level was done according to the manufacturer’s guide-

lines based on the sebum measurements, as follows: 1 - 2

µg/cm−2, low oil level; 3 - 6 µg/cm−2, normal oil level; 7 -

10 µg/cm−2, high oil level. Measurements of the five

facial sites were recorded and classified as follows: high

sebum secreting zone (T-zone: forehead, nose, and chin)

and low sebum secreting zone (U-zone: both cheeks).

Reference values for the skin surface oil levels (OL) of

the T-zone, U-zone and Mean Facial Sebum Excretions

(MFSE) were calculated using the following equations:

T-zone = the sum of CL of forehead, nose, and chin/3

U-zone = the sum of CL of right and left cheeks/2 MFSE =

the sum of CL of forehead, nose, chin, right and left

cheeks/5.

The skin surface pH levels of the five facial areas were

measured by the Skincheck-pH-Tester® (Hanna instru-

ments, Germany).

The electrode was washed with distilled water before

each measurement. The pH levels of the T-zone, U-zone,

and mean facial pH (MFpH) were calculated by using the

following equations: T-zone = the sum of pH of forehead,

nose, and chin/3 U-zone = the sum of pH of right and left

cheeks/2 MFpH = the sum of pH of forehead, nose, chin,

right and left cheeks/5.

The Demodex mite on four different sites of the face:

forehead (mid-glabella), nose tip, chin (mental promi-

nence), cheek (the most prominent area of both zygomas)

were discovered by as squeeze (fat gland squeezing) and

standard skin surface biopsy. The standardized skin sur-

face biopsies (SSSB) technique was a 1 cm2 (10 square

mm) red square was drawn on one side of the slide. A

droplet of cyanoacrylate glue was dropped on the area

where the specimen was to be taken and the reverse side

of the slide was pressed on the skin surface. The slide

was slowly removed from the skin after 30 s. The sam-

ples were brought to Laboratories National Dermatology

Center of Mongolia as shortly as possible. Two experien-

ced parasitology specialists under a light microscope at ×

100, × 200 and × 400 magnification examined the slides.

A subject divided into two groups with and without De-

modex folliculorum.

3. Statistical Analysis

The differences of skin surface sebum casual levels be-

tween subjects with and without D. folliculorum at the

five facial sites, T-zone, U-zone, and MFSE were tested

by an independent t-test after evaluating normality. The

same test was used to evaluate the differences of pH

between the two groups at the five facial sites, T-zone,

U-zone, and MFpH. The differences of skin surface

sebum casual levels among the five facial sites in each

population (subjects with and without D. folliculorum)

were tested using the ANOVA test after evaluating for

normality. These tests were used to assess pH differences

among the five facial sites in each population. The diffe-

rences in both skin surface sebum casual levels and pH

between the T-zone and U-zone in each population were

evaluated using the paired t-test. Relationships between

sebum casual levels and pH on the five facial sites,

T-zone, U-zone, MFSE, MFpH in each population were

tested using the Pearson Correlation Coefficient test. The

data were considered significant if P < 0.05, unless other-

wise noted.

4. Results

4.1. Differences of Skin Surface Sebum Casual

Levels between Subjects with and without

Demodex Folliculorum

The five facial areas, specially the nose and T-zone of the

subjects with Demodex folliculorum showed significant-

ly higher sebum casual levels, compared to the control

population. This difference resulted in statistically higher

Correlation Demodex Folliculorum and Skin Biophysical Parameters

224

sebum casual levels in the T-zone, and MFSE of the de-

modectic population than the control population. Skin

surface oil levels among the five facial areas differed

significantly in both subjects with and without Demodex

folliculorum (P < 0.001).

The mean and standard deviation of skin surface oil

levels of the four studied sites in the two groups as well

as the P-values are listed (Tables 1 and 2).

In subjects with Demodex folliculorum, the skin sur-

face oil level of the chin was significantly different than

that of the nose tip. When the skin surface oil levels on

the T-zone, U-zone were compared, skin surface oil le-

vels on the T-zone were significantly higher than those of

the U-zone (P < 0.001) in both populations (P < 0.01).

4.2. Differences in pH between Subjects with and

without Demodex Folliculorum

The pH levels of the five facial sites, T-zone, U-zone,

and MFpH in subjects with and without Demodex fol-

liculorum were compared (Figure 1).

The pH levels on the five facial sites, and U-zone,

T-zone and MFpH differed significantly in among both

subjects with and without Demodex folliculorum (“P <

0.001). When the pH levels on the U-zone, T-zone and

MFpH was compared in both populations (P < 0.01).

The pH levels between the five facial sites, and U-

zone, T-zone and MFpH differed significantly in both

subjects with and without Demodex folliculorum (P <

0.001). In both groups, the pH levels of the U-zone were

Table 1. The mean and standard deviation of skin surface

oil levels in group with Demodex folliculorum.

with Demodex folliculorum

Mean ± SD

(µg/cm−2) Nose tip

8.17 ± 1.324

Chin

7.48 ± 1.902

Forehead

7.3 ± 1.728

Cheek

5.54 ± 2.126

Nose tip P < 0.001 P < 0.001 P < 0.001

Chin - - P < 0.001 P < 0.001

Forehead - - - P < 0.001

Cheek - - - -

Table 2. The mean and standard deviation of skin surface

oil levels in group without Demodex folliculorum.

without Demodex folliculorum

Mean ± SD

(µg/cm−2) Nose tip

6.03 ± 1.500

Chin

5.05 ± 2.011

Forehead

5.34 ± 1.689

Cheek

4.43 ± 2.287

Nose tip - P < 0.001 P < 0.001 P < 0.001

Chin - - P < 0.001 P < 0.001

Forehead - - - P < 0.001

Cheek - - - -

(a)

(b)

Figure 1. Difference in pH between subjects with and with-

out Demodex folliculorum. (a): on the cheeks, chin, fore-

head, and nose tip. (b): on the T-zone, U-zone, and MFpH.

Filled bar subjects with Demodex folliculorum, grey bar

subjects without Demodex folliculorum, *P < 0.001.

significantly lower than the pH of the T-zone (P <

0.001).

4.3. Correlations between Skin Surface Oil

Levels and pH

Correlations between skin surface oil levels and pH on

the T-zone and U-zone in subjects with and without De-

modex folliculorum are shown (Figure 2).

Among the five facial sites in subjects with Demodex

folliculorum, there were significant negative correlations

between skin surface oil levels and pH on the forehead (p

Correlation Demodex Folliculorum and Skin Biophysical Parameters

225

(a1) (a2)

(b1) (b2)

Figure 2. Correlations between skin surface sebum casual level and pH. (a1), (a2): T-zone and (b1), (b2): U-zone in subjects

with Demodex folliculorum and without Demodex folliculorum. Filled triangle subjects with Demodex folliculorum, empty

square subjects without Demodex follic ulor um.

5. Discussion

< 0.001, r = 652), cheek (P < 0.001, r = 0.656), nose (P <

0.001, r = 0.754), chin (P < 0.001, r = 0.679), and T-zone

(P < 0.001, r = 0.698), MFSE-MFpH (P < 0.001, r =

0.483).

In this study, the skin surface sebum casual levels on the

nose of the population with Demodex folliculorum were

significantly higher than those of the control population,

which resulted in statistically higher skin surface sebum

casual levels on the T-zone and MFSE of the population

with Demodex folliculorum, compared to the control po-

pulation. These results are similar to the results of other

studies, showing that the acne is more intense in subjects

with Demodex folliculorum. However, there is a differ-

ence between this study and previously published studies

with regard to sebum secretion parameters and facial

areas which showed a significant difference. Pierard et al.

demonstrated different overall sebum excretion rates be-

tween subjects with and without acne when they mea-

In contrast, among the five sites in subjects without

Demodex folliculorum, a significant negative correla-

tions between skin surface oil levels and pH was ob-

served on the forehead (p < 0.001, r = 766), cheek (P <

0.001, r = 0.798), nose (P < 0.001, r = 0.706), chin (P <

0.001, r = 0.823), and T-zone (P < 0.001, r = 0.602), U-

zone (P < 0.001, r = −0.550).

Demodex mites was explored (p < 0.03) by 47.1 per-

cent of the healthy populations. The Demodex mite was

explored: 62.2 percent at people aged 16 - 20, 55.6 per-

cent at people aged then up 70 (r = 0.106, p < 0.02) (Ta-

ble 3).

Correlation Demodex Folliculorum and Skin Biophysical Parameters

226

Table 3. Correlation Demodex Folliculorum and study gr oups for age .

With Demodex Folliculorum Without Demodex Folliculorum

Age groups

(years) n n % n %

16 - 20 74 46 62.1 28 37.9

21 - 24 56 26 46.4 30 53.6

25 - 29 64 38 53.6 26 46.4

30 - 34 42 17 40.5 25 59.5

35 - 39 71 26 36.6 45 63.4

40 - 44 69 23 33.3 46 66.7

45 - 49 56 25 44.7 31 55.3

50 - 54 56 19 34 37 66

55 - 59 72 32 44.5 40 55.5

60 - 64 45 26 57.8 19 42.2

65 - 69 55 25 45.5 30 54.5

70 - 84 90 50 55.6 40 44.4

Total 750 353 47.1 397 52.9

n—number of subjects.

sured sebum secretion of foreheads using Lipometer®, a

photometric technique [7]. Pierard-Franchimont et al.

also demonstrated significant difference of the total se-

bum excretion on the forehead between subjects with

moderate acne and subjects without acne, whereas it did

not differ between subjects with mild acne and subjects

without acne [8].

The pH levels among the five facial sites, and U-zone,

T-zone and MFpH differed significantly in both subjects

with and without Demodex folliculorum (P < 0.001).

This may be due to the enlargement production pilose-

baceous glands.

However, there are several studies showing the nega-

tive effects of elevated pH on the skin. In the study of

Wendling et al., age did not correlate with skin pH [5,6,

9-11]. In addition, Zlotogorski showed no difference in

pH between the two genders [12].

The pH among the five studied sites differed signifi-

cantly in both subjects with Demodex folliculorum and

subjects without Demodex folliculorum (P < 0.001). In

fact, there is a general consensus in distinguishing facial

areas into the T-zone and U-zone depending on sebum

secretion. The difference in sebum secretion among dif-

ferent facial areas has been well-documented [13-17].

This study also showed that sebum casual levels of the

T-zone were significantly higher than those of the U-

zone in each population (P < 0.001). This may be associ-

ated with the difference in sebum secretion due in part to

significant negative correlations between sebum casual

levels and pH, which were also seen in this study. These

differences should be further examined in future studies

by young Mongolian investigators.

6. Conclusion

The sebum casual levels of the nose in the with Demodex

folliculorum population were significantly higher than

those of the without Demodex folliculorum population,

which resulted in statistically higher sebum casual levels

in the T-zone and MFSE of the population with Demo-

dex folliculorum, compared to the control population.

The pH of the five studied areas significantly differed

between two groups. The pH distribution among the fa-

cial five studied sites differed significantly in both sub-

jects with Demodex folliculorum and subjects without

Demodex folliculorum. The negative correlation between

sebum casual levels and pH was statistically significant

in the five studied areas and T-zone, MFSE-MFpH.

7. Acknowledgements

I strongly appreciate to everyone that helped my research

work. Special thanks to my supervisors Prof. Gurbadam

A. PhD in biology and Ass. Prof. Enkhtur Ya. MD, PhD

in dermatology, HSUM. Also let me express my grati-

tude to all the colleagues, Department of Biology and

Histology, School of Bio-Medicine, Department of Der-

matology, School of Medicine, HSUM, and National

Dermatology Center of Mongolia. Allow me to wish all

Correlation Demodex Folliculorum and Skin Biophysical Parameters 227

above mentioned associates the best in their further re-

searches and long lasting happy life.

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