[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Microbiology](https://durgical.com/en/microbiology/) › [Ectoparasites](https://durgical.com/en/microbiology/groups/ectoparasites/) › Demodex folliculorum and Demodex brevis

# Demodex folliculorum and Demodex brevis

- Parasite
- For completeness

Microscopic mites that live in almost everyone's hair follicles and oil glands. In large numbers they inflame the eyelids and face.

Updated Nov 13, 2026

Also called: follicle mites, eyelash mites

## Quick facts

**Type**
Parasite · [Ectoparasites](https://durgical.com/en/microbiology/groups/ectoparasites/)

**Gram / shape**
Worm-like

**Spread**
Close contact · Shared towels

**Causes**
Demodex blepharitis · Rosacea · Demodicosis

**Treatment**
Eyelids

On this page

- The basics Key points
- At a glance
- Morphology
- Transmission
- Life cycle
- Memory aid
- What the colours mean

- Clinical Virulence factors
- Diseases it causes
- Clinical picture
- Diagnosis

- Treatment Treatment
- Prevention

- Study Test yourself

- Connections Connections

## Key points

- Two human species: D. folliculorum (follicles, lashes) and D. brevis (sebaceous and meibomian glands).
- Almost universal in adults; disease when numbers rise.
- Collarettes at the base of the lashes: the hallmark of Demodex blepharitis.
- Linked to papulopustular rosacea; more than 5 mites per square centimetre supports demodicosis.
- Treatment: lid hygiene, tea tree oil, topical ivermectin or metronidazole.

## At a glance

**Shape**
Worm-like, elongated body with 4 pairs of stubby legs at the front

**Family**
Demodicidae

**Type**
Mites (arachnids), permanent commensal ectoparasites of human follicles

**Size**
D. folliculorum about 0.3–0.4 mm; D. brevis about half that

## Morphology

- Elongated, transversely striated body, with the legs and mouthparts at the front end.
- D. folliculorum lives in groups in hair follicles, including eyelashes.
- D. brevis lives alone deeper, in sebaceous and meibomian glands.

## Transmission

- Close contact: acquired from parents soon after birth; few in children, more with age.
- Shared towels, pillows and cosmetics may play a part.
- Almost all adults carry them; disease depends on mite numbers and the host's response.

**Reservoir:** Humans only (each mammal has its own Demodex species)

### Isolation precautions

What the care team adds to standard precautions.

- Standard

## Life cycle

- Adults mate at the follicle opening, mostly at night.
- The female lays eggs inside the follicle or gland.
- A six-legged larva hatches and becomes a protonymph, then a deutonymph.
- Nymphs move to new follicles and moult into eight-legged adults.
- The whole cycle takes about two to three weeks and happens on the human host.

## Virulence factors

- Mites block follicles and glands and damage the lining by feeding on cells and sebum.
- Dead mites and their bacteria trigger inflammation and immune reactions.
- Overgrowth in older adults, people with immunosuppression (such as HIV) and with topical corticosteroid use.
- In the eyelids, mites at the lash base cause collarettes, lash loss and meibomian gland dysfunction.

## Diseases it causes

- Demodex blepharitis [Blepharitis →](https://durgical.com/en/conditions/blepharitis/)
- Rosacea: higher mite numbers, especially in papulopustular forms [Rosacea →](https://durgical.com/en/conditions/rosacea/)
- Demodicosis: follicular scaling (pityriasis folliculorum), papules and pustules on the face
- Perioral-like dermatitis and conjunctival inflammation

## Clinical picture

- Itchy, red eyelid margins with cylindrical waxy dandruff (collarettes) around the lash base.
- Lash loss, gritty or burning eyes and dry eye symptoms.
- Face: fine follicular scaling, redness, papules and pustules, often asymmetric.

## Diagnosis

- Slit-lamp view of collarettes at the lash base strongly suggests ocular Demodex.
- Light microscopy of plucked eyelashes shows mites.
- Skin: standardised skin surface biopsy or scraping; more than 5 mites per square centimetre supports demodicosis.
- Dermoscopy may show spiky white structures plugging follicle openings.

## Treatment

Eyelids: daily lid hygiene, warm compresses, tea tree oil preparations or a topical acaricide approved for Demodex blepharitis. Skin: topical acaricides such as ivermectin cream, metronidazole, permethrin or benzyl benzoate; oral ivermectin in severe or immunosuppressed patients.

Drug class only; doses and regimens are set by the clinician from the current guideline.

In Pharmacology:

- [Ivermectin](https://durgical.com/en/pharmacology/ivermectin/)
- [Metronidazole](https://durgical.com/en/pharmacology/metronidazole/)
- [Permethrin](https://durgical.com/en/pharmacology/permethrin/)
- [Benzyl benzoate](https://durgical.com/en/pharmacology/benzyl-benzoate/)

## Prevention

- Regular lid and facial cleansing with non-oily products.
- Avoid heavy oil-based creams and unnecessary topical corticosteroids on the face.
- Do not share towels, pillowcases or eye cosmetics; replace old eye make-up.

## Memory aid

Folliculorum lives in the follicle, brevis goes briefly deeper into the gland; a collar on the lash means mites at home.

## Test yourself

Think of the answer, then tap the question to see it.

## What eyelid sign is typical of Demodex blepharitis?

Collarettes: cylindrical waxy dandruff wrapped around the base of the eyelashes.

## Where does Demodex brevis live?

Alone, deeper in sebaceous glands and in the meibomian glands of the eyelids.

## Which skin disease is associated with higher Demodex density?

Rosacea, especially the papulopustular form.

## How is demodicosis of the skin confirmed?

By standardised skin surface biopsy or scraping showing more than about 5 mites per square centimetre.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/microbiology/demodex-folliculorum-and-demodex-brevis/)

## What the colours mean

**Gram-positive**
Thick peptidoglycan wall: stains purple.

**Gram-negative**
Thin wall with an outer membrane: stains pink.

**Acid-fast**
Lipid-rich wall (mycobacteria): Ziehl–Neelsen stain.

## Connections

## Related 3

- [Sarcoptes scabiei](https://durgical.com/en/microbiology/sarcoptes-scabiei/)
- [Trombicula, Cheyletiella and bird mites](https://durgical.com/en/microbiology/trombicula-cheyletiella-and-bird-mites/)
- [Dermatophagoides and Blomia tropicalis](https://durgical.com/en/microbiology/dermatophagoides-and-blomia-tropicalis/)

## Related conditions 2

- [Blepharitis](https://durgical.com/en/conditions/blepharitis/)
- [Rosacea](https://durgical.com/en/conditions/rosacea/)

[← Back to the group: Ectoparasites](https://durgical.com/en/microbiology/groups/ectoparasites/)

Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: [Demodex, demodicosis](https://dermnetnz.org/topics/demodex) (DermNet, 2023); [Blepharitis: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/001619.htm) (MedlinePlus (NLM), 2024); [Arthropod infestations. Arachnid bites and stings](https://dermnetnz.org/cme/arthropods/arachnid-bites-and-stings) (DermNet, 2023).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/microbiology/demodex-folliculorum-and-demodex-brevis/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/microbiology/demodex-folliculorum-and-demodex-brevis/