Sociodemographic characteristics and risk factor analysis of Demodex infestation (Acari: Demodicidae)

Abstract

Abstract:To identify sociodemographic characteristics and risk factor of Demodex infestation, 756 students aged 13-22 years in Xi'an, China were sampled for the school-based cross-sectional study. Demodex was examined using the cellophane tape method (CTP). The results showed that the total detection rate of Demodex was 67.6%. Logistic regression analysis revealed that five variables (gender, residence, sharing sanitary ware, frequency of face-wash per day, and use of facial cleanser) were found to be uncorrelated with Demodex infestation, whereas three variables (age, skin type, and skin disease) were found to be independent correlates. Students aged over 18 years had 22.1 times higher odds of Demodex infestation compared to those under 16 years and students aged 16-18 years also had 2.1 times higher odds compared to those aged 13-15 years. Odds of having a Demodex infestation for oily or mixed skin were 2.1 times those for dry or neutral skin. Students with a facial skin disease had 3.0 times higher odds of being infested with Demodex compared to those without. The inception rate of students with facial dermatoses increased in parallel with increasing mite count. The inception rates were 21.3%, 40.7%, 59.2%, and 67.7% in the negative, mild, moderate, and severe infestation groups, respectively (χ 2 =60.6, P<0.001). Specifically, the amount of infested mites and inception rate of acne vulgaris were positively correlated (R 2 =0.57, moderate infestation odds ratio (OR)=7.1, severe infestation OR=10.3). It was concluded that Demodex prevalence increases with age, and Demodex presents in nearly all adult human. Sebaceous hyperplasia with oily or mixed skin seems to favour Demodex proliferation. Demodex infestation could be associated with acne vulgaris. The CTP is a good sampling method for studies of Demodex prevalence.

A meta-analysis of association between acne vulgaris and Demodex infestation

“…However, it is not related as closely to Demodex infestation (OR 2.80, 95% CI, 2.34-3.36) as rosacea is (OR 7.57,95% CI,. The possible reason is that age of onset in acne vulgaris is younger than that in rosacea, which is in negative correlation with that Demodex infestation rises with age (Divani et al, 2009;Zhao et al, 2011a). On the one hand, in acne vulgaris, as adolescents gradually age, they secrete androgen, and their sebaceous glands mature, resulting in pubertal acne.…”

“…Only if excess Demodex was detected could we associate the lesions with Demodex. In the present study, although we included and analyzed 63 papers about the association between Demodex infestation and acne vulgaris, only 3 English papers (Baysal et al, 1997;Zhao et al, 2011a;2011b) matched the inclusion criteria. Also only one study we could searched used SSB method (Okyay et al, 2006), and it did not match the inclusion criteria.…”

“…According to the inclusion and exclusion criteria mentioned above, 60 Chinese papers covering 25 provinces/municipalities and only 3 English papers (Baysal et al, 1997;Zhao et al, 2011a;2011b) were eligible, which consisted of 42 130 subjects in total including students and residents, aged from 1 to 78 years. Most of the subjects were university and middle school students who were prone to acne vulgaris in the age of 11 to 25 years.…”

Facial dermatosis associated with Demodex: a case-control study

“…It is worth clarifying that although English papers about the association between Demodex infestation and AV are very few and mostly give negative conclusions (Baysal et al, 1997;Okyay et al, 2006), a great number of Chinese papers have reported a positive association between Demodex infestation and the development of AV (Yang et al, 2006;Ma et al, 2009;Wang et al, 2010;Zhao et al, 2011b). Moreover, effective acaricidal treatments have also supplied indirect proof of a causal relationship between Demodex infestation and AV (Yang et al, 2006;Ma et al, 2009).…”

Cloning and sequence analysis of chitin synthase gene fragments of Demodex mites

“…Up to now, 140 species or subspecies have been identified, infesting the hair follicles, sebaceous glands, meibomian glands, and internal organs of 11 orders of mammals such as human, dog, sheep, cat, pig, and (Izdebska, 2010;Mederle et al, 2010), goat demodicidosis (Smith, 1961;Xu et al, 2009), livestock demodicidosis (Chakrabarti and Pradhan, 1985), and human demodicidosis (Ayres and Anderson, 1932;Ayres and Ayres, 1961;Forton and Seys, 1993;Forton et al, 2005;Zhao et al, 2010;2011a;2011c;2012c). However, the pathogenesis of demodicidosis is still uncertain, and there are no effective prevention measures.…”