What are Demodex mites?
Demodex mites are tiny mites that live in the hair follicles and oil glands of human skin. There are two species that live on humans:
- Demodex folliculorum – Lives in the hair follicles
- Demodex brevis – Lives in the sebaceous glands
These mites are very small, only about 0.3-0.4 mm long. They are transparent and worm-shaped. Demodex mites are a normal part of human skin flora. Nearly every adult human has them living on their skin.
Are Demodex mites harmful?
For most people, Demodex mites do not cause any problems or symptoms. They live harmlessly on the skin, only coming out at night to mate and feed on skin oils and dead skin cells. However, in some cases, having too many mites can lead to skin disorders like demodicosis.
What is demodicosis?
Demodicosis refers to skin conditions caused by an overgrowth of Demodex mites. When mite populations get out of control, they can cause irritation, inflammation, and other skin issues. There are two main types of demodicosis:
- Demodicosis folliculorum – Caused by D. folliculorum mites in the hair follicles. This leads to itchy rashes, acne-like breakouts, and scaly skin on the face, cheeks, forehead, or nose.
- Demodicosis brevis – Caused by D. brevis mites in the oil glands. This causes red swollen bumps, pustules, and skin thickening on the face.
What causes demodicosis?
It’s not fully understood why Demodex mites multiply out of control in some people. Possible causes include:
- Weakened immune system – Allows mites to proliferate.
- Hormonal changes – Such as during puberty, pregnancy, or menopause.
- Skin inflammation – From conditions like rosacea, eczema, or sun damage.
- Stress
- Poor hygiene
- Genetics
Certain medications and health conditions are also linked to increased risk of demodicosis, such as:
- Immunosuppressant drugs
- Cancer chemotherapy
- Diseases like diabetes, leukemia, HIV/AIDS
- Long-term steroid use
For most healthy individuals, outbreaks of demodicosis are sporadic and temporary. But people with weakened immune systems may deal with chronic, recurrent episodes.
What are the symptoms of demodicosis?
Symptoms of demodicosis can include:
- Itchy, irritated skin
- Redness and inflammation
- Rashes or bumps on the face
- Flaky, scaly skin
- Enlarged pores
- Thickened skin
- Eye inflammation or styes
The exact symptoms depend on the type of demodicosis:
Demodicosis folliculorum symptoms:
- Itchy rashes on the face, especially cheeks, chin and forehead
- Acne-like breakouts
- Greasy skin
- Scaly or crusted skin patches
Demodicosis brevis symptoms:
- Firm, swollen, red bumps and pustules
- Oily, thickened skin
- Rosacea-like facial flushing
- Blepharitis (eyelid inflammation)
In rare cases, a severe Demodex infestation can even lead to skin disfigurement and scarring if left untreated.
How is demodicosis diagnosed?
To diagnose demodicosis, a skin scraping is done to look for an overabundance of mites under the microscope:
- The doctor scrapes a small amount of skin from the affected area onto a slide.
- This sample is examined under a microscope to look for Demodex mites.
- A diagnosis is made if there are more than 5 mites per 1 cm square area of skin.
Other tests may include a skin biopsy to examine tissue samples. Your doctor will also look for characteristic symptoms of demodicosis. Multiple areas are often sampled because mites can be localized.
How is demodicosis treated?
There are several ways to treat an overgrowth of Demodex mites on the skin:
Medicated creams and lotions
Creams and lotions containing insecticides or anti-parasitic drugs can kill mites. Common prescription medications used include:
- Crotamiton (Eurax)
- Permethrin (Elimite)
- Ivermectin (Sklice, Soolantra)
- Metronidazole
- Benzyl benzoate
These are applied to affected areas of skin and left on for a period before washing off. Treatments are typically continued for 2-3 weeks.
Oral medications
Oral ivermectin tablets can be prescribed for more severe, widespread demodicosis cases. It works by paralysing and killing mites systemically after absorption into the bloodstream.
In-office procedures
For severe demodicosis, doctors may use:
- Acaricidal agents – Applied in office to kill mites
- Skin scrapings – To manually remove mites from lesions
Supportive care
Other ways to help treat demodicosis include:
- Face washing with anti-mite cleansers
- Avoiding irritants like harsh soaps
- Topical steroids to reduce inflammation
- Antibiotics for secondary bacterial infections
Properly treating any underlying conditions, such as rosacea, can also help lower mite counts. With consistent treatment, demodicosis usually clears up within a few weeks.
Are Demodex mites contagious?
Demodex mites are not considered contagious under normal circumstances. Nearly all adult humans already have them living on the skin. Close contact like touching or kissing does not typically spread mites from person to person.
However, people with weakened immune systems may be susceptible to mite transfer. For example, Demodex mites have been reported to sometimes spread between sexual partners or from mother to newborn at birth. But this kind of transmission seems to be rare.
How can I prevent demodicosis?
To help prevent problematic overgrowths of Demodex mites:
- Wash your face regularly with tea tree, neem, or sulfur-containing cleansers to control mite populations.
- Avoid irritating the skin with harsh scrubs or astringents.
- Treat skin conditions like acne, rosacea, and eczema to minimize skin inflammation.
- Reduce stress, get adequate sleep, and eat a healthy diet to support immune function.
- Avoid sharing towels, bedding, or pillows if you have a weakened immune system.
Conclusion
Demodex mites are normal skin inhabitants that only cause issues for some people. Overgrowths can lead to demodicosis, causing itchy rashes and skin inflammation. People with weakened immune systems or certain skin conditions are most at risk. Diagnosis involves skin scrapings to look for excessive mites under a microscope. Treatments include medicated creams, oral ivermectin, and in-office procedures. Preventing demodicosis involves keeping mite populations in check, avoiding skin irritation, and supporting overall immune health. While contagious spread is unlikely, those with compromised immunity should take precautions. With proper treatment, most cases of demodicosis resolve quickly without complication.