Demodex mites are tiny mites that live in the hair follicles and oil glands of human skin. While they are a normal part of skin flora, an overgrowth of demodex mites can lead to a condition called demodicosis or demodex infestation. In this article, we will explore what causes demodex mites to proliferate and lead to infestation.
What are demodex mites?
Demodex mites are tiny arachnids that belong to the species Demodex folliculorum and Demodex brevis. They are naturally found on human skin and measure only 0.3-0.4 mm long – making them invisible to the naked eye. These mites feed on skin cells and oils inside hair follicles, most commonly on the face including cheeks, nose, chin and forehead.
While demodex mites inhabit most adult humans, they normally exist in balance with the immune system and do not cause issues. The mites become problematic when their population grows out of control, leading to skin conditions like demodicosis.
What causes demodex mite overgrowth?
In healthy individuals, demodex mites are kept under control by the body’s immune responses and self-grooming habits like regular face washing. However, certain factors can disrupt this balance and promote demodex proliferation and infestation:
Weakened immune system
Demodex mites are naturally suppressed by the skin’s immune defenses. Conditions that weaken immunity like malnutrition, HIV, immunosuppressive drugs or chemotherapy can impair control over mite populations.
Hormonal changes
Hormonal fluctuations during adolescence, pregnancy or menopause may increase sebum production and provide more food for mites.
Genetics
Studies suggest genetics can predispose some individuals to having higher baseline numbers of demodex mites.
Skin damage
Skin damage from conditions like rosacea, burns, dermatitis or wounds can allow more mites to penetrate deeper into the skin.
Age
Older adults tend to harbor more mites as immune function declines with age. Numbers increase after age 50.
Poor hygiene
Infrequent face cleaning or makeup removal prevents manual removal of mites and oils on which they feed.
Steroid creams
Long-term use of topical steroid creams like hydrocortisone can thin the skin and suppress immune defenses.
Other skin conditions
Rosacea, eczema, seborrheic dermatitis and blepharitis (eyelid inflammation) provide favorable environments for mites.
Risk factors for demodex infestation
While anyone can get demodex overgrowth, certain groups are at higher risk:
- Teenagers – hormonal changes stimulate oil production
- Pregnant women – increased hormones enlarge oil glands
- Menopausal women – hormonal shifts can increase oil gland activity
- Patients on immunosuppressive medications
- Patients undergoing chemotherapy
- People with HIV/AIDS
- People with chronic skin conditions like eczema or rosacea
- Elderly individuals – increased mite colonization with age
Symptoms of demodex infestation
Most people with demodex mites do not experience symptoms. However, some individuals with excessive proliferation develop the following:
- Itching or stinging skin
- Redness and rashes, sometimes with scaly texture
- Pimple-like bumps or pustules
- Eye inflammation and styes
- Crusting or scaly eyelashes and eyebrows
Symptoms are usually localized to the face, cheeks, nose, chin, forehead and eyelids – areas rich in oil glands where mites thrive. In rare cases, large infestations may spread to the neck, chest and back.
Diagnosing demodex infestation
Demodex overgrowth is often overlooked or misdiagnosed because symptoms resemble other conditions like acne, rosacea or allergic reactions. However, a dermatologist can identify demodicosis through the following methods:
Skin scraping
Using a scalpel, the doctor gently scrapes cells from affected areas onto a microscope slide. This reveals adult mites, eggs and larvae if infestation is present.
Skin biopsy
A minor surgery extracts a small skin sample to be examined under a microscope. A biopsy can provide a definitive diagnosis by showing mites embedded in the skin.
Slide presses
Clear adhesive tape applied to the face lifts away debris. Microscopic inspection of the tape detects eggs and mites.
Treating demodex infestation
Treatment aims to eliminate excessive mites and manage symptoms. Options may include:
Prescription creams and lotions
Medications like crotamiton 10%, sulfur preparations, benzyl benzoate, permethrin and ivermectin 1% kill mites through various mechanisms.
Oral ivermectin
For severe or resistant cases, oral ivermectin tablets can reduce mites systemically. Effects may take several weeks.
Hygiene measures
Diligent face washing, scrubbing with antibacterial soap and hot compresses can help manually decrease mite populations and oils.
Topical antibiotics
If pustules and bumps become infected, antibiotic creams/gels treat secondary bacterial infection.
Topical corticosteroids
Short-term steroid creams like hydrocortisone provide relief from itching and skin inflammation.
Adjunct oral antibiotics
Oral antibiotics may help reduce skin bacteria and inflammation but have limited direct effect on mites.
Home remedies for demodex mites
In addition to medical therapies, some home remedies may help reduce mite populations:
Tea tree oil
Tea tree oil is thought to kill mites through solvent properties. Dilute before applying a few drops to the skin.
Natural oils
Plant-based oils like coconut, olive and jojoba oils may help suffocate mites and dissolve oils on which they feed.
Aloe vera gel
Pure aloe vera gel has anti-inflammatory properties to soothe irritated skin and antimicrobial effects to kill mites.
Honey
Honey is a natural antibacterial agent. Applying small amounts overnight and rinsing in the morning may reduce mites.
Neem
Neem oil and neem leaf extracts have antifungal and anti-inflammatory properties to fight infestations.
However, note that these natural remedies have limited evidence for demodex mites specifically. Consult a dermatologist before using to avoid complications.
Prevention of demodex mite overgrowth
Preventing excessive proliferation of demodex mites involves:
- Washing the face twice daily with soap to remove dirt, oil and mites
- Using a facial cleanser formulated for your skin type
- Exfoliating regularly with scrubs or brushes to slough off dead skin cells where mites reside
- Avoiding sharing towels, linens and pillowcases to limit mite transfer
- Treating underlying skin conditions like rosacea that can foster mite growth
- Moisturizing to improve skin barrier function
- Removing makeup thoroughly before bedtime
- Using over-the-counter acaricides and anti-mite ingredients like benzyl benzoate
- Keeping makeup brushes clean and replacing them regularly
Improving hygiene and skin health creates an unfavorable environment for demodex mites to thrive.
Conclusion
In summary, demodex mite infestation results from overproliferation of these microscopic mites that normally live in small numbers on human skin. Weakened immunity, hormonal shifts, poor hygiene, skin damage and age allow mite populations to expand. Symptoms include itching, rashes, pimples and eye inflammation. Diagnosis involves skin scraping and biopsy, while treatment options include topical and oral medications alongside hygiene measures. Preventing excessive growth of demodex mites relies on face cleansing, exfoliating, treating underlying skin conditions and improving skin barrier health.