Who can live on hair besides lice? - briefly
Mites (e.g., Demodex), certain fungi, and bacterial colonies can also inhabit hair shafts. While usually harmless, they may contribute to conditions such as blepharitis or dandruff.
Who can live on hair besides lice? - in detail
Hair supports a diverse community of microscopic and macroscopic organisms that are not lice. These inhabitants fall into several categories: arachnids, fungi, yeasts, bacteria, and occasional insects.
-
Mites
Demodex folliculorum and Demodex brevis reside within hair follicles and sebaceous glands. They feed on skin cells and sebum, reaching densities of several hundred per follicle in some individuals. Overpopulation can contribute to blepharitis, rosacea, and facial dermatitis. Diagnosis relies on microscopic examination of expressed follicular contents; treatment options include topical acaricides such as tea‑tree oil or ivermectin. -
Fungal pathogens
Dermatophytes (Trichophyton, Microsporum, Epidermophyton) colonize the keratinized shaft, causing tinea capitis. Infections manifest as scaling, alopecia, and sometimes pustules. Laboratory confirmation uses culture or molecular assays. Systemic antifungals (e.g., griseofulvin, terbinafine) are required for cure. -
Yeasts
Malassezia species inhabit the scalp surface, metabolizing lipids and producing irritating metabolites. Their proliferation underlies dandruff and seborrheic dermatitis. Antifungal shampoos containing ketoconazole, selenium sulfide, or zinc pyrithione reduce yeast load and alleviate symptoms. -
Bacterial flora
The hair environment hosts commensal bacteria such as Staphylococcus epidermidis, Cutibacterium acnes (formerly Propionibacterium acnes), and various Corynebacterium spp. These organisms form a stable microbiome that competes with pathogens. Disruption by harsh detergents or excessive moisture can shift the balance toward opportunistic infections like folliculitis, which responds to topical antibiotics or antiseptic washes. -
Occasional insects
Flea larvae, dust mites, and stray beetles may be found on hair, especially in unsanitary conditions. Their presence is transient; removal typically involves thorough cleaning and environmental control rather than pharmacologic therapy.
Understanding the full spectrum of hair‑dwelling organisms informs accurate diagnosis and targeted management. Microscopic analysis, culture, and molecular testing remain essential tools for distinguishing among these entities.