Blepharitis and Demodex Spp. Infection
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REVIEW DOI: 10.5603/OJ.2017.0006 Blepharitis and Demodex spp. infection Karolina Kot1, Maciej Czepita2, Danuta Kosik-Bogacka1, Natalia Łanocha-Arendarczyk1, Damian Czepita2 1Department of Biology and Medical Parasitology, Pomeranian Medical University, Szczecin, Poland 2 Department of Ophthalmology, Pomeranian Medical University, Szczecin, Poland ABSTRACT According to the latest reports Demodex mites appear to play an important role in the pathogenesis of chronic ble- pharitis. Demodex mites are cosmopolitan and are present in many species of mammals. In this paper we describe two species that are found in humans: Demodex folliculorum and D. brevis. Infection occurs during direct contact with an affected person and also through contact with dust containing eggs of the parasite, through contact with bed linen, as well as cosmetics used together with an affected person. Treatment of chronic blepharitis caused by D. folliculorum and D. brevis is difficult and time consuming. Some improvement can be achieved after topical application of yellow mercury ointment, sulphuric ointment, camphor oil, crotamiton, cholinesterase inhibitors, sulfacetamide, steroids, antibiotics and antifungal drugs. Good results have been achieved with oral ivermectin and permethrin cream. However, the best results were observed after treatment with metronidazole. KEY WORDS: pathogenesis, infection, ocular demodicosis, treatment Ophthalmol J 2017; Vol. 2, No. 1, 22–27 INTRODUCTION troversial because they can also be found in healthy Blepharitis can be caused by bacterial or fungal individuals [3]. Based on the results of current stud- infection, allergic reaction, metabolic disease, uncor- ies, it is estimated that Demodex mites are present in rected refractive errors, and Demodex spp. Anterior 10% of healthy people and can be found in 12% of blepharitis is usually caused by staphylococcal infec- their hair follicles [4]. It is postulated that D. fol- tion, while posterior blepharitis is usually related to li culorum becomes pathogenic when it reproduces meibomian gland dysfunction or seborrheic blepha- intensively, causing increasing ocular symptoms [5]. roconjunctivitis. Recent reports have highlighted the importance of Demodex mites in the patho- genesis of chronic blepharitis, especially in cases BIOLOGICAL PROPERTIES with weak reaction to treatment. Recurrent horde- Demodex mites have a vermiform shape and are ola and chalazia can be a result of Demodex spp. covered by a thin cuticle (Fig. 1). Demodex fol- infection [1]. liculorum are larger (0.3–0.4 mm) and are more Demodex mites are cosmopolitan and are there- elongated. They live in larger groups in the orifices fore found in different species of mammals. At the of hair follicles. Demodex brevis is smaller (0.2– time of writing, two species have been found in –0.3 mm) and has a fusiform shape and short legs. It humans: Demodex brevis (Akbulatova, 1963) and can be found in single sebaceous glands throughout D. folliculorum (Simon, 1842). Recently these two the facial skin and also in the meibomian glands species have been classified as parasites after previous- of the eyelids [6]. The body of Demodex mites can ly being described as commensals [2]. However, the be divided into the gnathosoma with the mouth- pathogenicity of these two species of mites is con- part, the podosome, and the opisthosoma. In both CORRESPONDING AUTHOR: Dr hab. n. med. Danuta Kosik-Bogacka, prof. PUM, Department of Biology and Medical Parasitology, Pomeranian Medical University, Powstancow Wlkp. 72, 70–111 Szczecin, Poland, tel.: +48 91 466 17 98, e-mail: [email protected] 22 Copyright © 2017 Via Medica, ISSN 2450–7873 Karolina Kot et al., Blepharitis and Demodex spp. infection A B C D FIGURE 1. Developmental stages of Demodex folliculorum: A — egg; B–D — adults (magnification 100×) species the podosome has four pairs of legs and three velopment of Demodex spp. ranges from 16 to 20°C. pairs in larvae. The gnathosoma of D. folliculorum The parasites stop feeding at temperatures below contains sharp and more dagger-like mandibles than 0°C or above 37°C. At temperatures above 54–58°C in D. brevis, which serve to take up food, and palps they die. Demodex mites prefer an acidic environ- that are necessary to hold food. The mandibles serve ment and are sensitive to UV radiation [10–11]. to cut the epithelium of the hosts skin. The parasites excrete enzymes that can initially digest food, after which the mites suck it in. This form of feeding causes EPIDEMIOLOGY the destruction of the epithelium and the penetration Demodex folliculorum and D. brevis most of- of the parasite into the deeper layers of the skin. The ten occur in elderly patients. Cheng et al. [12] main food source in all stages of development are the found a prevalence rate of 84% in a population components of serum. As a result, the parasites thrive aged 60 years and almost 100% in a population in areas that are especially rich in sebaceous glands over 70 years old. Garbacewicz et al. [13] noted [7–8]. The life cycle of D. folliculorum lasts between a low prevalence in young people (5%), which 14 and 18 days. The development is simple and it can probably be attributed to excretion of smaller occurs in only one host. The female lays eggs, from amounts of sebum by the sebaceous glands of which larvae initially without legs hatch. The larvae Zeiss and the Meibomian tarsal glands in children then develop three pairs of unsegmented legs. Af- and teenagers [11]. ter the first moulting, the larvae transform into an Infection occurs through direct contact with an eight-legged nymph, and after another two moultings affected person and most likely through contact into an adult form, either female or male [9]. with dust containing eggs of the parasite, through Demodex spp. is sensitive to changes in temper- contact with bed linen, or by sharing the same cos- ature and pH. The optimal temperature for the de- metics with an affected person [14–15]. Moreover, www.journals.viamedica.pl/ophthalmology_journal 23 OPHTHALMOLOGY JOURNAL 2017, Vol. 2, No. 1 it has been discovered that eggs of Demodex spp. Demodex spp. infection has been noted in patients can be found in microscope eyepieces. The results with HIV, leukaemia, or cancer [28, 29]. Demodex spp. of studies carried out by Garbacewicz et al. [13] has been diagnosed in patients with diabetes, renal showed that 30% of people using a microscope were failure, and in patients undergoing haemodialysis infected with Demodex spp. [3, 25, 28, 30]. The factors having an influence on Demodex spp. There are publications proving a relationship be- infection are profession, type of skin, dermatological tween Demodex spp. infection and blepharitis. Tian illnesses, living standards, housing and work place and Chao-Pin [31] examined 507 patients with standards, as well as personal hygiene habits [8]. blepharitis and noted that 50.7% of patients have Wesołowska et al. [16] found that Demodex spp. Demodex spp. The authors also observed Demodex occurs in 40% of people of a medical profession spp. in 58 patients (11.7%) with other eye dis- such as doctors, nurses, and physiotherapists, and eases. Türk et al. [32] observed D. folliculorum in in 33.7% of medical students and 23.5% of drug 29.7% of patients with blepharitis, in 9.1% of pa- abusers. Ocular demodicosis can be a result of the tients with blepharoconjunctivitis, and in 4.2% of presence of mites on the facial skin [17–18]. Demo- patients in a control group. Bhandari and Reddy [5] dex spp. infection has been observed in 47% of peo- discovered the mites in 78.7% of people with ple with oily skin, in 26.6% of people with dry skin, chronic blepharitis. However, Kemal et al. [33] did and in 33.9% of people with a mixed complexion. not observe any statistically significant difference of People with dermatological illnesses such as rosacea the prevalence of Demodex spp. in patients with and and skin acne are more susceptible to Demodex spp. without blepharitis. Wesołowska et al. [16] similarly infection (62%) than healthy people (27.6%). did not observe any higher prevalence of demodi- A higher infection rate has been also observed in pa- cosis in people wearing eyeglasses or contact lenses. tients living in areas of humid climate (67.9%) than in people living in areas of dry climate (24.5%) [19]. Wesołowska et al. [16] described a higher prevalence PATHOGENESIS of Demodex spp. infection among people living in Demodex mites feed on the cells lining hair older housing (43.5%) than among people living follicles. Metabolites and undigested leftovers can in newer housing (39.4%). However, the difference accumulate at the base of eyelashes and create cy- was not statistically significant. lindrical dandruff, which is pathognomonic for oc- Some researchers have described the prevalence ular demodicosis [12]. Demodex spp. mechanically of Demodex spp. infection to be related to the sex of block sebaceous glands, irritate the eyelids, and in- the examined patients. Raszeja-Kotelba et al. [20] duce hypertrophy of the epithelium and hyperkera- and Forton et al. [21] have given a higher intensity tinisation. Demodex spp. may induce in the host of infection in women than in men, which was at- a granulomatous inflammation and immunologic tributed to the use of creams and powders as well as response [34–35]. Köksal et al. [36] have observed being influenced by sex hormones. However, Hor- a granuloma within a Meibomian gland harbouring váth et al. [22] observed that the infection rate was Demodex spp. and surrounded by epithelial cells, higher in men than in women. Yamashita et al. [23] stromal cells, fibroblasts, lymphocytes, and plasmat- and Kuźna-Grygiel et al. [14] as well as Wesołows- ic cells. In studies carried out by Liang et al.