Demodex mites are tiny mites that live in or near hair follicles. There are more than 50 known species of Demodex mites, but only two are found on humans: Demodex folliculorum and Demodex brevis.
What are Demodex Mites?
Demodex mites are microscopic arachnids that are related to spiders and ticks. They are obligate parasites, meaning they require a host to survive. Demodex mites feed on skin cells and oils inside hair follicles.
Demodex Folliculorum
Demodex folliculorum is the most common species found on humans. These mites are elongated in shape and typically measure 0.3-0.4 mm long. D. folliculorum live inside the hair follicles, primarily on the face, forehead, cheeks, nose, and eyelashes.
Demodex Brevis
Demodex brevis is shorter and stouter than D. folliculorum, measuring 0.2-0.3 mm long. D. brevis resides deeper in the sebaceous glands connected to hair follicles and meibomian glands on the nose and eyelids.
Can Demodex Mites Be All Over the Body?
Demodex mites are most commonly found on the face and eyelashes, but can also occur on other parts of the body. Whether Demodex mites can be found all over the body depends on the species.
Demodex Folliculorum
D. folliculorum prefers to reside in the hair follicles on the face near the sebaceous (oil) glands. However, D. folliculorum has been found in lower numbers on the scalp, neck, chest, back, genital area, and buttocks. Overall, D. folliculorum tends to concentrate around the face and upper body.
Demodex Brevis
D. brevis has been found on the face, nose, ears, eyelids, chest, forearms, genital area, and buttocks. One study found D. brevis mites in the external auditory canal in over 60% of ear wax samples analyzed. Compared to D. folliculorum, D. brevis appears to have a wider distribution around the body.
Factors Affecting Demodex Distribution
Several factors can influence where Demodex mites reside on the body:
- Oil production – Demodex mites prefer to live in areas with high sebum production, such as the face, scalp, and upper back.
- Hair follicles – Demodex are found inside hair follicles, so they will be limited to hairy regions of the body.
- Hormones – Androgens may stimulate mite growth, partially explaining the concentration on the face and scalp.
- Immune suppression – Weakened immune function can lead to increased mite density and distribution.
Can Demodex Mites Spread Across the Entire Body?
Healthy adults generally do not have Demodex mites spread across the entire body. However, there are some circumstances in which Demodex mites can potentially occur over the whole body:
Newborns
Demodex mites are transferred from mother to child during birth and breastfeeding. For the first few months of life, infants may have a more generalized distribution of mites that eventually concentrates to the face as the immune system matures.
Immunosuppression
People who are immunosuppressed, such as chemotherapy patients or those taking immunosuppressant medications, are more prone to develop generalized demodicosis with mites all over the body. This is due to their weakened immune system being unable to control mite proliferation.
Skin and Hormonal Disorders
Certain skin disorders, such as rosacea and eczema, can create an environment suitable for Demodex mites to spread across the skin. An excess of male hormones or clogged pores may also encourage mite dispersal. Overall skin inflammation seems to contribute to mite propagation beyond their normal facial territory.
Is it Possible to Completely Eradicate Demodex Mites?
It is very difficult to fully eradicate Demodex mites from the skin. Even with treatment, some mites are likely to remain.
Reasons Demodex Mites Persist After Treatment
- Mites have a short reproductive cycle – eggs can hatch in as little as 20-24 hours, allowing quick repopulation.
- Mites reside deep in hair follicles and sebaceous glands, making it hard for treatments to penetrate.
- Some individuals may be genetically predisposed to carry higher mite loads.
- Mites transfer between close human contacts.
However, reducing mite density through hygiene and topical treatments can control symptoms and minimize risk of spreading.
Treatment Options for Demodex Mites
While eradication is difficult, treatments are available to reduce Demodex mite density:
Over-the-Counter Treatments
- Tea tree oil
- Sulfur creams or soap
- Salicylic acid
- Benzoyl peroxide
Prescription Medications
- Ivermectin
- Crotamiton
- Metronidazole
Improving hygiene by washing bedding frequently and avoiding sharing towels or makeup can also minimize mite transmission. Overall, a combination approach is best.
Conclusion
In summary, while Demodex mites prefer the face, they can occasionally be found all over the body, especially in certain conditions like immunosuppression. Generalized demodicosis is more common with D. brevis than D. folliculorum. Although eradication is not really feasible, reducing mite density through hygiene and medications can control symptoms. More research on the triggers for atypical Demodex spread could help target treatments more effectively.