A Survey on Demodex Infections for Undergraduate Students in Some Universities in Ningbo City of Zhejiang Province of China ()
Subject Areas: Infectious Diseases, Respiratory Medicine
1. Introduction
Demodex families are kinds of small permanent parasitic mites, namely sebaceous follicle Demodex and brevis Demodex. The two parasites mainly parasitize the body of man’s forehead, nose, chin and zygomatic places. Mechanical and chemical stimulation can cause skin diseases such as acne, seborrheic dermatitis, and folliculitis [1] . As a result of investigation, Demodex infection rate presents the different levels. Thus, we had investigated the Demodex infections in College students of Ningbo City from December 2012 to March 2013. The results have been shown as follows.
2. Materials
Investigated people: totally 600 people, 336 boys and 264 girls at 2009-2011 grades of college students of Ningbo City.
3. Methods
Survey methods [2] : The survey contents include personal diet, accommodation environment, hygiene, etc. At the same time, recording client’s age, gender, facial disorders, health situation, the collective life and infection degree standards
Checking out any Demodex infections are considered to be positive. Infection degrees of each sample are calculated, all degrees are divided into 3 levels, level 1 is to be degree I (mild); level 2 is to be degree II (moderate); level 3 is to be degree III (serious).
Types of infections: The infection types are divided into three types: sebum Demodex infection, brevis infection and mixed infections with follicles.
All data are treated with spss12.
4. Results
4.1. The Infection Rates of Demodex Mites
All tables showed include 600 university students, among 195 infected students, male’s infection rate was 35.71%, female’s infection rate was 28.41%, infection rate between male and female students with P values were more than 0.05, which means no statistical significance (Table 1).
4.2. The Infection Degrees with Demodex Mites
Among 195 students infected, first-degree infection rate accounted for 72.82%, second-degree infection rate accounted for 15.90%, third-degree infection rate accounted for 11.28% (see Table 2).
4.3. Facial Diseases and Mite Infection
The face demonstrated seborrheic dermatitis, folliculitis of Demodex infection rates were greater than the normal facial skin infected, facial diseases and mite infection’s P value was less than 0.01, there was a statistically significant difference (see Table 3).
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Table 1. University students’ facial Demodex infection rate.
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Table 2. Infection degree of university students with facial Demodex mites.
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Table 3. The Demodex infections of facial skins.
4.4. Conditions of Demodex Infections among Students Who Use Skin Care Products and Those Who Don’t Use
The number of students who use skin care products is 139, the positive rate was 30.48%, while the number of those who don’t use was 56, positive rate was 38.89%. The positive rate for whom uses skin care products and those with products not used among students with Demodex infections, their P values are greater than 0.05, means no statistical significance (Table 4).
4.5. The Ratio of Different Infections with Demodex
Among 195 students’ Demodex infections, simple follicle Demodex are 97 people, simple sebum Demodex are 77 people, and 21 people with mixed infections (Table 5).
4.6. Demodex Infections among Urban and Rural Students
Among 473 students who live in rural areas, 153 people are positive, the infection rate was 32.35%. Among 127 students who live in the city, 42 people were positive, urban the infection rate was 33.07%, where P values were greater than 0.05, which had no statistical significance (Table 6).
4.7. Different Ways of Cleansing Demodex Infections of Students
Cleansing 133 people with water, which is effective for 57 people, the positive rate was 45.86%; cleansing 49 people using soap, which is effective for 49 people, the positive rate was 26.53%; cleansing 411 people using cleanser, which is effective for 123 people, the positive rate of 29.93%; commonly using soap intergrated cleanser to cleanse 7 people, 2 were effective, the positive rate was 28.57%. Calculated with the chi-square test, P value was less than 0.05, with highly statistical significance (Table 7).
4.8. The Treatment of Facial Demodex Cases Using Various Drugs
Treating students with 2% mebendazole mixture , 39 cases were negative, negative rate was 78%; oral metronidazole tablets in patients, 43 were negative, negative rate of 86%; oral tinidazole tablets in patients, 44 were negative, negative rate of 88%; Compatibly treated with metronidazole ointment of pure pink and yellow snake patients, there were 47 negative, negative rate was 94%; Compatibly treated with sulfur ointment and glycerol patients, there were 49 negative, negative rate was 98%; patients treated with cream, 13 people were negative, negative rate was 26%. P values were less than 0.01, which were statistically significant (Table 8).
5. Discussion
Demodex infections are distributed worldwide, and the population infection rate abroad is about 27% - 100% [3] , but the infection rate in China is about 20% - 70% [4] . The Demodex infection rate of all college students is greatly different, too. In the investigation into College students in some universities in Ningbo City, the Demodex infection rate is 32.50%, which is in accordance with the domestic normal infection rate. The main causes of the differences in the rate of infections with Demodex are attributed to geographical environment, climatic conditions, the season of checking, the site of checking and inspection methods, etc. In this research, we had investigated into the mites infections at the same population using scraping pressure method and sticking method. The results showed that the former method was better than the latter in the nose and face detection. The detection
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Table 4. The comparison of Demodex mites infection between students who use and who don’t.
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Table 5. Different infection cases.
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Table 6. Demodex infections among urban and rural students compared to the different situations.
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Table 7. Cleansing Demodex infections on students with different ways compared to the infections’ situations.
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Table 8. The treatment of demodex infections using different drugs.
rate is association with the amount of sebum. The more the amount of sebum is, the higher the detection rate is [4] . Demodex mites parasitic in hair follicles and sebaceous glands which mechanically stimulate and secrete some pathological factors can damage the hair follicles and sebaceous glands, leading to hair follicle expansion and epithelial degeneration; at the same time, they are also able to lead to the dermal telangiectasia, hyperplasia, and blocking of sebaceous gland secretion. The worms can carry pathogenic microorganisms, when at concurrent bacterial infection, causing the hair follicle cell infiltration, fibrous tissue hyperplasia, performance for the local skin flushing, hyperaemia, inflammation, enlarged pores, and rough surfaces. In this paper, the total Demodex infection rate was 32.50%, the infection rate was 35.71% for males, and 28.41% for females. The differences from infection rate of male and female are not statistically significant, but most reports such as Zhang [5] find that men have a higher rate of infection than women, the cause of which still needs further study. We had detected the different types of Demodex infections mainly including Demodex follicurolum, Demodex brevis and mixed infections [6] . In infected persons, infections of Degree I accounted for 72.82% of the total, Degree II infections accounted for 15.90%, and Degree III infections accounted for 11.28%, which was consistent with the infections of Demodex mites reported before [7] . For patients with or without acne, our survey showed that infection rate of patients with acne was higher than those without acne, which had statistical significance. So, Demodex is one of the causes of acne for patients [8] , and water cleansing is the destruction of drying and high- temperature conditions, making people susceptible to infection of vermiform mite. But if using soap and cleanser alkaline substances, normal human can resist the infection of vermiform mite. In the experimental groups with different treatments, the best use of combined sulfur ointment and glycerin coated metronidazole in pure powder and snake yellow ointment to the experimental groups, and the negative rate for infections reached 98% and 94%. We found that experiments coated with ointment smearing part had important significance for patients, the patients applied in nose and nasal groove parts, and the negative rate was higher than those applied in cheeks. Propagation on Demodex infections of populations who are more vulnerable to infection is necessary. Therefore, to prevent infection, we should enhance propaganda, enable students to understand the knowledge on Demodex prevention, developing good health habits, washing supplies special, paying attention to personal hygiene, keeping the face clean, trying to avoid close contact with patients, and cutting off the transmission route [9] . Patients with being positive for infections with acne, rosacea and other facial diseases should be timely treated, lest loss of illness would be incurred because of delay [10] - [12] .
NOTES
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*Corresponding author.