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.
Received July 25th, 2013; revised August 24th, 2013; accepted August 31st, 2013
Copyright © 2013 Ts. Sarangua et al. This is an open access article distributed under the Creative Commons Attribution License,
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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