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Methods for Quantifying Demodex Mites


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Quantification for Demodex Density Counts

What are the numbers revealing? In normal humans demodex density is reported to be "1 or 2 per square centimetre of skin". In rosacea sufferers with demodectic rosacea "the number rises to 10 to 20." [1]

Methods and Tools Used to Quantify 

There are a number of methods or tools used to quantify demodex density counts. We will continue to update this page as we learn more. 

Cellophane Tape Method, Scraping, Plucking Eyelash and Eyebrow Hair

"Methods used to collect Demodex mites from humans include biopsy, the cellophane tape method (placing tape on the face to stick to the mites), scraping areas where mites are likely to reside, and plucking eyelash and eyebrow hairs." [2]

Confocal Laser Scanning Microscope (CLSM)

confocal-laser-scanning-microscope_thumb.jpg

A paper published by the British Journal of Dermatology reports, "With the help of CLSM it is possible to non-invasively detect, image and quantify Demodex mites in facial skin of patients with rosacea." [3]

The Confocal Laser Scanning Microscope [CLSM] hopefully will be in every dermatologist's office so that we can get some data on how may sufferers have demodectic rosacea. [4]

Another paper discusses the Confocal LS Microscope and stated, "there are limitations to the use of this method to accurately detect absolute numbers of mites in human skin." [5]

An article in 2014 says, "Reflectance confocal microscopy is a fast, direct and noninvasive method for Demodex-associated diseases and it is superior to SSSB for Demodex mite detection." [6]

According to a Russian study, the CLSM in vivo method is the best method of quantifying demodex density counts which needs to be validated by comparing the other tools used. 

Cellophane Tape Method (CTP, Squeezing Method, Skin Scrapings, and the Standardized Skin Surface Biopsy (SSSB)

"To collect mites for further research, the cellophane tape method (CTP), squeezing method, or skin scrapings can be used. CTP seems to be more effective with a positive rate at 91%, whereas squeezing gives a 34% positive diagnosis. Standardized Skin Surface Biopsy (SSSB) is the most commonly used method for comparing densities of mites between patients with dermatoses and healthy controls." [7]

SNS [superficial needle-scraping

Direct Microscopic Examination (DME) & SSSB

168px-Compound_Microscope_(cropped).jpg
Compound Microscope image courtesy of Wikimedia Commons

"Standardized skin surface biopsy (SSSB) and direct microscopic examination (DME) are commonly used to determine Demodex mites density (Dd)." [8]

Another paper in Thailand states that SSSB has been 'considered to be the gold standard technique' but after careful investigation that the Skin Scraping technique is just as valid. [9]

Microscope (simple)

Potassium Hydroxide (KOH)

"Potassium hydroxide (KOH) preparation of skin scrapings is a much simpler procedure that can be used to detect pathogens in the superficial skin...Potassium hydroxide preparation of skin scrapings is an effective, time saving and practical technique to detect Demodex mites with accuracy comparable to the standard biopsy method." [9]

SLI [scattered light intensity]

SSSB with DME Better Than CLSM?
According to one report,  if you use a skin scraping with a light microscope, no, which says, "The severity of the condition does not depend on the quantitative load of the mites in the scrape." However when using a 'Confocal laser scanning in vivo microscopy', yes, which this same report concludes, "Confocal laser scanning in vivo microscopy is an effective diagnostic method to detect Demodex mites that does not require preliminary preparation for analysis and allows detecting Demodex mites at the level of the spiky epidermis layer, which is not accessible for scarification, to identify the species belonging to the size of Demodex mites (from 100 up to 200 μm - Demodex brevis, 200 to 400 μm – Demodex folliculorum)." [10]

SSSB [standardized skin surface biopsy

DERMOSCOPY

dermoscopy.png

The advantage of dermoscopy can be shown in a report by Friedman et al which states,"Our case is an example of how dermoscopy could have helped in demodicidosis recognition, since the patient was incorrectly treated with topical steroids possibly with the diagnosis of seborrheic dermatitis. However, when we evaluated the patient, dermoscopy did not reveal what would be expected for seborrheic dermatitis (dotted vessels in a patchy distribution and fine yellowish scales), but revealed, instead, features associated with demodicidosis (“Demodex tails” and “Demodex follicular openings”). [11]

"In 54 patients, the dermoscopy examination yielded a specific picture consisting of Demodex "tails" and Demodex follicular openings. In patients with an inflammatory variant of demodicidosis, reticular horizontal dilated blood vessels were also visualized. Microscopically, skin scrapings demonstrated Demodex in 52 patients. Overall, the dermoscopy findings showed excellent agreement with the microscopy findings (kappa value 0.86, 95% CI 0.72–0.99, P < 0.001)." Dermoscopy of demodicidosis shows the so-called "Demodex tails", which are visualised as creamy/whitish gelatinous threads protruding out of follicular openings (black arrow), and “Demodex follicular openings”, which appear as round and coarse follicular openings containing light brown/greyish plugs surrounded by an erythematous halo (black arrowhead) (f).  See Fig 4, Item f  [12]

A paper by Karabay et al shows photos of using SSSB. [13]

"Besides diagnostic purposes, dermoscopic assessment in erythro-telangiectatic rosacea may also be helpful in monitoring post-treatment changes (with reduction of vascular and non-vascular findings, especially when treated with lasers) and predicting therapeutic response to topical treatments [32]. Indeed, according to a preliminary analysis on 20 patients suffering from erythro-telangiectatic rosacea, the presence of protruding follicular plugs is associated with a better response to an 8-week course of ivermectin 10 mg/g cream compared to metronidazole 1% gel used for the same time span (personal observations). This would be due to the possible active effect of the former therapy on Demodex folliculorum as there is a correlation between protruding follicular plugs on dermoscopy and a higher mite density that may be seen in rosacea (typically less than 5 mites/cm2)." [15]

Dermatoscopy

Fluorescence-advanced videodermatoscopy

What is Dermatoscopy?

"Improvements with dermatoscope attachments to mobile devices enable dermatoscopic images to be easily uploaded into patients’ medical records. Dermatoscopes will continue to become smaller. Hopefully, image uploading capabilities will become integrated into these devices. Eventually, dermatoscopes will utilize MBL algorithms to offer diagnostic suggestions." [14]

Do It Yourself (DIY)

Supereyes Macro Lens-Disposable Dermatoscope

Supereyes Smartphone Microscope Camera Adapter

Thumbnail-squeezing method

End Notes

[1] Demodex Density Count - What are the Numbers?

[2] Plos | One
Ubiquity and Diversity of Human-Associated Demodex Mites
Megan S. Thoemmes , Daniel J. Fergus, Julie Urban, Michelle Trautwein, Robert R. Dunn

[3] Br J Dermatol. 2012 Jun 20. doi: 10.1111/j.1365-2133.2012.11096.x.
 
Non-invasive in vivo detection and quantification of Demodex mites by confocal laser scanning microscopy.
Sattler EC, Maier T, Hoffmann VS, Hegyi J, Ruzicka T, Berking C.

[4] Counting Demodex Mites with a Confocal Laser Microscope
David Pascoe, Rosacea Support Group

[5] Br J Dermatol. 2013 Feb 16. doi: 10.1111/bjd.12280. 
Demodex quantification methods: Limitations of Confocal Laser Scanning Microscopy (CLSM).
Lacey N, Forton FM, Powell FC.

[6] Skin Res Technol. 2014 Feb 13.
Reflectance confocal microscopy vs. standardized skin surface biopsy for measuring the density of Demodex mites.
Turgut Erdemir A, Gurel MS, Koku Aksu AE, Bilgin Karahalli F, Incel P, Kutlu Haytoğlu NS, Falay T.

[7] Iran J Parasitol. 2017 Jan-Mar; 12(1): 12–21. PMCID: PMC5522688
Human Permanent Ectoparasites; Recent Advances on Biology and Clinical Significance of Demodex Mites: Narrative Review Article
Dorota LITWIN,  WenChieh CHEN, Ewa DZIKA, and Joanna KORYCIŃSKA

[8] Ann Dermatol. 2017 Apr; 29(2): 137–142.
Demodex Mite Density Determinations by Standardized Skin Surface Biopsy and Direct Microscopic Examination and Their Relations with Clinical Types and Distribution Patterns
Chul Hyun Yun, Jeong Hwan Yun, Jin Ok Baek, Joo Young Roh, and Jong Rok Lee

[9] Indian J Dermatol Venereol Leprol [View Image]
Skin scrapings versus standardized skin surface biopsy to detect Demodex mites in patients with facial erythema of uncertain cause – a comparative study
Sumanas Bunyaratavej, Chuda Rujitharanawong, Pranee Kasemsarn, Waranya Boonchai, Chanai Muanprasert, Lalita Matthapan, Charussi Leeyaphan

[10] Dermatol Reports. 2019 Jan 23; 11(1): 7675.
Clinical picture, diagnosis and treatment of rosacea, complicated by Demodex mites
Alexey Kubanov, Yuliya Gallyamova, and Anzhela Kravchenko

[11] Dermatol Pract Concept. 2017 Jan; 7(1): 35–38.
Usefulness of dermoscopy in the diagnosis and monitoring treatment of demodicidosis
Paula Friedman, Emilia Cohen Sabban, and Horacio Cabo

[12] Int J Dermatol. 2010 Sep;49(9):1018-23.
Dermoscopy as a diagnostic tool in demodicidosis.
Segal R, Mimouni D, Feuerman H, Pagovitz O, David M.

[13] An Bras Dermatol. 2020 Mar-Apr; 95(2): 187–193.
Demodex folliculorum infestations in common facial dermatoses: acne vulgaris, rosacea, seborrheic dermatitis
Ezgi Aktaş Karabay and Aslı Aksu Çerman

[14] J Am Acad Dermatol. 2019 Apr; 80(4): 1121–1131.
Emerging imaging technologies in dermatologyPart II: Applications and limitations
Samantha L. Schneider, MD, Indermeet Kohli, PhD, Iltefat H. Hamzavi, MD, M. Laurin Council, MD, Anthony M. Rossi, MD, and David M. Ozog, MD

[15] Dermatol Ther (Heidelb). 2020 Oct 08;:
Dermoscopy in Monitoring and Predicting Therapeutic Response in General Dermatology (Non-Tumoral Dermatoses): An Up-To-Date Overview.
Errichetti E

 

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