demodectic

Demodectic refers to Demodex mites, tiny parasitic arachnids that inhabit the hair follicles and sebaceous glands of mammals, including humans and many domestic animals. The two species most commonly found on humans are Demodex folliculorum and Demodex brevis. In people, these mites are typically harmless residents, and many individuals carry them without symptoms. Prevalence tends to increase with age.

Biology and ecology: Demodex mites live in follicles and sebaceous glands on the face, scalp, and eyelids, among other sites. They have a small life cycle that includes egg, larval, nymph, and adult stages. Transmission is usually by close contact, such as between partners or household members, and populations can rise when the host’s immune response is altered.

Pathology: When mite numbers become excessive or trigger inflammation, the condition is termed demodicosis or demodectic mange in animals. In humans, overgrowth has been associated with disorders such as rosacea and blepharitis. Symptoms, when present, can include itching, facial redness, scaling, and changes to hair or eyelashes.

Diagnosis: Diagnosis is made by detecting mites in skin or lash samples. Techniques include skin surface biopsy, skin scrapings, or eyelash plucking followed by microscopic examination to count mites.

Treatment and management: Management aims to reduce mite burden and control inflammation. Approaches may include eyelid hygiene, antiseptic or acaricidal agents, and, in some cases, prescription medications such as ivermectin or other antiparasitics. In animals, demodectic mange is treated under veterinary supervision with species-appropriate regimens. Prognosis varies with host factors and the presence of concurrent conditions.