WHAT IS DEMODEX?

Demodex is an eight-legged mite from the family Demodicidae. There are many species of Demodex, but only two of them are found in humans, demodex folliculorum and demodex brevis. Demodex mites are naturally present on the human face from childhood, but especially after the age of 18. Their presence on the skin increases with age. They live in or around the hair follicles (where the hair grows) and sebaceous glands (glands attached to the hair follicles that secrete sebum, an oily substance that prevents the skin and hair from drying out).1 They form part of the microorganisms that naturally live on our skin.

LIFE PROCESS

Demodex mites need humans to live, they develop naturally on our skin until their death2. The life cycle from egg to adult mite takes 14 to 18 days. Eggs are deposited in sebaceous glands and hair follicles, then they develop into larvae until they develop into adult form. In some cases, larger numbers of Demodex develop, which is thought to cause significant inflammation and lead to the appearance of skin lesions. However, the mechanism behind these reactions is not fully understood. WHAT ARE THE SYMPTOMS OF DEMODEX? Demodex mites are not considered to be true disease carriers. However, when these parasites are more numerous on the skin, they can create conditions that favor the appearance of certain symptoms and pathologies. The waste that accumulates in their abdomen during their life is only released at their death. In cases where they become very common, this residue can cause skin irritation and redness due to the development of chronic inflammation and vascular abnormalities.

EYELIDS, BLEPHARITIS AND DEMODEX

Demodex may be the cause of blepharitis, an inflammation of the eyelid margin.
Demodex blepharitis manifests as non-specific clinical symptoms in all types of blepharitis, regardless of the cause (bacteria, virus, etc.), including
- Redness and itching at the edge of the eyelid,
- Sensation of sand or foreign body,
- Eyelash loss,
- In severe forms, swelling of the eyelids, painful ulcers on the eyelid margins.
It may include some symptoms such as the following:
- Pigmentation of the eyelid margin
- Presence of transparent or whitish scales forming a crusted rash about 1 mm from the base of the eyelashes: this is the most characteristic and frequent symptom and is called cylindrical dandruff.
The diagnosis of Demodex blepharitis is confirmed by microscopic analysis of an eyelash sample or by seeing the parasites with a slit lamp (40-fold magnification) during an ophthalmologist's examination.

DEMODEX AND ROSACEA MANIFESTATIONS

Demodex also creates conditions that favor the development of Rosacea, which causes the small vessels under the skin of the face to dilate. Redness appears on the cheeks, sides of the nose, forehead and chin. As the disease progresses, the symptoms become permanent. As the disease develops, it often causes the appearance of small red pimples (or papules). This facial pathology usually affects adults over the age of 20 and peaks between the ages of 40 and 508. The severity of Rosacea is linked to ocular conditions such as Xerophthalmia (dry eye), Conjunctivitis or even Keratitis or Blepharitis (see above). Excessive Demodex can be demonstrated by skin squamous analysis.

DEMODEX TREATMENT

BLEPHARITIS TREATMENT

After diagnosis, your Ophthalmologist will recommend treating Demodex blepharitis with a specific daily eye care routine. As described in a recent international guideline9 , the treatment of Demodex blepharitis requires specialized treatments, such as topical products containing tea tree oil. Where treatment is not successful or for more severe forms of the condition, an antibiotic or anti-parasitic treatment may be prescribed by an ophthalmologist and used in addition to a daily cleansing routine.