1. DEMODEX MITE

2. INTRODUCTION
• Gk - Demos -
Fat ; Dex - Wormwood
• ‘The Mighty Mite’ aka ‘Eyelash Mite’ or ‘Face Mite’
• 65 known species, mostly commensal
• Phylum Arthropoda Family Demodicidae ; Suborder ;
Prostigmata
• Demodex aries aurati brevis bovis canis caprae caballi
cati cornei criceti equi folliculorum gapperi gatoi injai ovis
phyloides zalophi

3. INTRODUCTION
• Isolated from Cerumen by Jakob Henle (1841)
• Gustav Simon described as Acarus folliculorum
(1842)
• Demodex coined by Richard Owen (1843)

4. DEMODEX
• Obligate Pilosebaceous gland parasites – Man /
Dogs / Cats (Mange)
• 02 main species :
D. Folliculorum
(Longer 0.2 – 0.4 mm)
D. Brevis
(0.1 – 0.2 mm / Sebaceous)

5. • A

6. • aa

7. PATHOGENESIS
• Contain Lipase ; found in areas high with sebum viz
forehead, cheeks, nasolabial folds, scalp, external ear, in eyelash
follicles meibomian glands, upper chest and nipples
• D. folliculorum - head-down position in the follicle, often with the
tip of the abdomen protruding from the follicular orifice.
• Follicle mites are quite motile, and migrate from follicle to follicle.
Most infested follicles contain two to six mites, but occasionally
they are much more numerous.
• Mites have been isolated from individuals of all ages, except
neonates (close maternal contact?)
• Prevalence inc with age
• Skin-surface biopsy / scraping identifies clusters

8. CLINICAL FEATURES
• 02 distinct presentations:
• 1) PITYRIASIS FOLLICULORUM
Earlier described in Middle-aged or older women who rarely
washed their faces, but used large quantities of make-up and
cleansing creams.
Diffuse facial erythema and follicular plugs, which impart a
‘nutmeg grater’ appearance to the skin
Skin scrapings contained unusually large numbers of Demodex

9. • aa

10. CLINICAL FEATURES
•
2) ROSACEA-LIKE ERUPTION
Rosacea merely provides Environment for multiplication of the mites, or whether the
mites play a role in initiating the disease.
?Local, delayed hypersensitivity response to Demodex antigens - inflammatory
component of rosacea
Bacterial antigens associated with Bacillus oleronius, isolated from D. folliculorum,
stimulate inflammatory response in PapuloPustular rosacea
Extrafollicular Demodex or fragments of Demodex may be found in the granulomatous
lesions of rosacea – immune-mediated destruction and extrusion of mite remains
Mite identified from Papulo-Pustular Rosacea but not from Pustular Acne
Response to Miticidal agents, not to Metronidazole

11. CLINICAL FEATURES
• Implicated in papular and papulopustular lesions in
immunosuppressed indls - Leukemia / MF / HIV-positivity
• Facial lesions attributed to Demodex have been described in
immunocompetent children
• D. folliculorum density in perioral dermatitis suggested that
increased mite density was a secondary phenomenon related to
topical steroids, and also showed that mite density increased
significantly in relation to the length of treatment
• Presence in Eyelash follicles has been implicated in the
pathogenesis of blepharitis

12. OTHER ASSOCIATIONS
• Fungal spores and Mycobacterium leprae within
Demodex mites – Vectors ??
• LMDF
• SEBORRHOEIC DERMATITIS
• GROVER’S DISEASE
• AGA

13. • aa

14. • aa

15. DDx
•
•
•
•
•
•
•
Rosacea (Papulo-Pustular)
Acne Vulgaris
Eosinophillic Folliculitis
Hydroa Vacciniforme
Folliculitis
LMDF
Trichoepithelioma / Syringoma
• Phthiriasis Pubis (Eyelids)

16. DIAGNOSIS
• Direct Microscopy / KOH Mount of expressed
pilosebaceous contents by Comedone
Extractor
• Skin Surface Biopsy
• Skin Biopsy

17. SKIN SCRAPING

18. TREATMENT
• Cleansing with Soap / Water
• Miticidal agents – Benzoyl Benzoate / Lindane
1%
• BPO 5%
• Precipitated Sulphur 5%
• Permethrin 1% X 10 mins
• Ivermectin 0.5% Lot X 10 mins
• Ivermection Oral – Off label in Blepharitis

19. THANK YOU