Skin Mites — Scabies & Demodex (स्केबीज़ / डेमोडेक्स)
MBBS/MD level clinical guide • हिंदी (primary) + English medical terms • Ready for Blogger paste
- Introduction — क्या हैं Skin Mites?
- Pathophysiology & Incubation
- Clinical Presentation — Scabies vs Demodex
- Differential Diagnosis & Complications
- Investigations / Pathology Tests
- Treatment — Topical & Systemic (age-wise doses)
- Supportive medicines & Symptomatic Care
- Environment & Contact Management
- Diet / Foods to Avoid & Recommend
- Follow-up, Prevention & Public Health
- FAQ (schema included)
- References
Overview
Clinical
Introduction — क्या हैं Skin Mites?
"Skin mites" का सामान्य रूप से आशय Sarcoptes scabiei (scabies mite) और Demodex spp. (face/eyelash mites: Demodex folliculorum, Demodex brevis) से होता है। Scabies एक contagious ectoparasitic skin infestation है जो तीव्र itching और characteristic burrows देता है; Demodex सामान्यतः मानवीय तवचा का commensal है पर overgrowth पर rosacea-like या blepharitis symptoms दे सकता है। 0
Pathophysiology & Incubation
- Sarcoptes scabiei: female mite epidermis के stratum corneum में burrow बनाती है, eggs एवं faeces immune response trigger करते हैं → severe pruritus (यह type IV hypersensitivity मे शामिल माना जाता है)। Initial infestation में symptoms प्रायः 2–6 सप्ताह बाद आते हैं; re-infestation में तेज़ (days) पर लक्षण दिखते हैं। 1
- Demodex spp.: hair follicles और sebaceous glands में रहते हैं; sebaceous/immune dysregulation पर overpopulation → papulopustular eruptions, rosacea-like inflammation, blepharitis. Diagnosis often requires mite counts by standardized sampling. 2
Clinical Presentation — Scabies vs Demodex
Scabies (Sarcoptes scabiei)
- Intense nocturnal pruritus (रात में बढ़ती खुजली) — hallmark.
- Typical sites: interdigital web spaces, flexor aspects of wrists, anterior axillary folds, periumbilical, waistline, genitalia; infants/young children may have scalp, face, palms, soles involved.
- Signs: burrows (thin gray-brown lines), papules, vesicles, secondary excoriations, crusting (severe/crusted scabies)।
- Systemic features uncommon unless secondary bacterial infection (e.g., streptococcal cellulitis) develops.
Crusted (Norwegian) Scabies
Immunocompromised patients में hyperinfestation — thick crusts, extremely high mite burden, high transmission risk; requires combined topical + systemic regimens and infection control. 3
Demodex (face / eyelash mites)
- Often asymptomatic; symptomatic cases: facial prickling, burning, persistent erythema, papulopustular lesions (esp. T-zone), blepharitis (crusting at lash base), and rosacea exacerbation.
- Risk factors: oily skin, steroid overuse, immunosuppression, cosmetic practices (extensions, poor eyelid hygiene).
Differential Diagnosis & Complications
- Contact dermatitis, atopic dermatitis, insect bite reactions, papular urticaria
- Pityriasis rosea, folliculitis, bacterial impetigo (secondary infection)
- Complications: secondary bacterial infection (impetigo, cellulitis), post-streptococcal glomerulonephritis (rare after streptococcal skin infections), severe outbreaks in institutions
Investigations / Pathology Tests
- Direct microscopy (skin scraping): mineral oil skin scraping examined under light microscope to identify mites, eggs, fecal pellets — diagnostic for scabies.
- Dermoscopy: “jet with contrail” or delta-wing sign for scabies burrows; useful bedside tool.
- Lash sampling / standardized skin surface biopsy (SSSB): for Demodex density quantification.
- Skin swab & culture: if secondary bacterial infection suspected — for pathogen ID & sensitivity (esp. streptococci/staphylococci).
- Blood tests: CBC (leukocytosis with secondary infection), ESR/CRP if systemic signs; blood cultures if sepsis suspected.
Treatment — Principles
Goal: eradicate mites, relieve pruritus, treat secondary infection, and prevent transmission. Treatment choice depends on infestation type (classical vs crusted), patient age, pregnancy/lactation status, weight, and local availability/resistance patterns. Permethrin topical and oral ivermectin are the mainstays. 4
Topical Agents (First-line for classic scabies)
| Agent | How to use / Dose | Notes |
|---|---|---|
| Permethrin 5% cream | Apply neck-to-toe (including flexures, groin, genitalia); leave 8–14 hours (overnight). Repeat once after 7 days if persistent. For infants, apply to scalp as per local guidance. | Safe in pregnancy & lactation per many guidelines; treatment of choice in many countries. Ensure whole household treated simultaneously. 5 |
| Benzyl benzoate 25% lotion | Apply to whole body below neck; repeat as per product instructions (often nightly for 2–3 nights). Dilute in children per regimen. | More irritating; avoid on broken skin; used in resource-limited settings. 6 |
| Topical ivermectin 1% cream | Apply once (some regimens repeat after 7–14 days) as per product insert. | Effective for scabies and Demodex; useful when permethrin unavailable or not tolerated. 7 |
Oral Agents
| Agent | Adult dose | Paediatric / Notes |
|---|---|---|
| Ivermectin (oral) | 200 μg/kg per dose; commonly given as two doses 7–14 days apart for classic scabies. For crusted scabies, multiple doses (e.g., days 0, 1, 7, 8, 14; regimen guided by specialist) combined with topical therapy. 8 | Not recommended in pregnancy; caution in children <15 absorption.="" by="" children.="" dose="" food="" for="" guideline="" increase="" kg="" take="" td="" to="" variable="" weight-based="" with=""> |
| Oral antibiotics | Only if secondary bacterial infection: e.g., for cellulitis — oral cephalexin / flucloxacillin according to local protocols. | Culture & sensitivity if severe or non-responsive. Treat secondary infection per standard guidelines. |
Demodex — Treatment
- Topical ivermectin 1% cream or permethrin preparations can reduce Demodex density; tea tree oil (terpinen-4-ol) products useful adjuncts for lid hygiene and blepharitis. Evidence supports topical ivermectin and TTO in reducing mite counts and symptoms. 10
- Ocular demodicosis (blepharitis): lid hygiene + tea-tree based cleansers; topical ivermectin formulations or lotilaner ophthalmic solutions emerging as effective options (specialist/ophthalmology management advised). 11
Practical Age-wise / Special Groups Notes (MBBS level)
- Infants and young children: many guidelines permit permethrin 5% cream use (with careful application) even in infants — follow local pediatric guidance. Ivermectin oral often avoided in children <15 kg.="" li="">
- Pregnancy & breastfeeding: permethrin usually preferred; ivermectin generally avoided in pregnancy (insufficient safety data). Consult obstetrician/dermatologist. 12
- Crusted / immunosuppressed patients: combined topical + multiple doses oral ivermectin under specialist supervision; strict infection control (isolation, PPE) often required. 13
Important dosing reminder: Ivermectin dose is weight-based (200 μg/kg). Permethrin regimen requires full-body application and treatment of close contacts simultaneously. Always check local formularies & product inserts for paediatric dilutions and exact application instructions.
Supportive medicines & Symptomatic Care
- Antihistamines (oral): e.g., cetirizine 5–10 mg once daily (adult) for pruritus relief; sedating H1 at night (promethazine/loratadine alternatives) for sleep disturbance. Adjust pediatric dosing by weight. (Symptomatic only.)
- Topical emollients & antipruritics: calamine lotion, topical 1% hydrocortisone (short course) for severe inflammation — avoid masking infection.
- Antibiotics: for secondary bacterial infection — choose agent per culture & local guidelines (e.g., oral cephalexin for streptococcal/staphylococcal cellulitis unless MRSA suspected).
- Pain control: paracetamol / NSAIDs as required (follow contraindications).
Environment & Contact Management
- Treat household contacts and close contacts simultaneously even if asymptomatic (high secondary attack rate).
- Wash bedding, clothing, towels in hot water (≥60°C) and tumble-dry on high heat; or seal items in plastic bag for ≥72 hours (mites survive off-host only ~48–72 h). 14
- Vacuum furniture & carpets; clean commonly touched surfaces. Staff in institutional outbreaks may require work restrictions until treated per public health guidance. 15
Diet — Foods to Avoid & Recommend (Adjunctive care)
No specific diet eradicates mites; however, optimizing skin health and immune function helps recovery and prevents secondary infection.
Recommended
- Protein-rich foods (lean meat, eggs, legumes) — wound healing & immune support.
- Vitamin C rich fruits & vegetables (citrus, guava, bell peppers) — collagen synthesis & immunity.
- Omega-3 fatty acids (fish, flaxseed) — may modulate inflammation.
- Probiotics / fermented foods in patients on long antibiotics to maintain gut flora (optional, per physician).
Avoid / Minimize
- Excess refined sugars and ultra-processed foods (can exacerbate inflammation and skin microbiome imbalance).
- Topical oily cosmetic products that may occlude follicles (esp. Demodex prone skin) — avoid heavy greasy creams on T-zone.
- Avoid OTC topical steroids on undiagnosed pruritic eruptions — may worsen Demodex proliferation / mask scabies features.
Follow-up, Prevention & Public Health
- Re-examine after 1–2 weeks to confirm clinical response; persistent pruritus can persist 2–4 weeks post-treatment (post-scabetic pruritus) despite cure — differentiate from treatment failure.
- For outbreaks (schools, nursing homes), coordinate with local public health — mass drug administration (ivermectin MDA) effective in high prevalence settings per WHO recommendations. 16
- Educate patients on hygiene measures, household cleaning, and need to treat contacts.
FAQ — Frequently Asked Questions
क्या scabies contagious है?
हाँ — skin to skin संपर्क और infected bedding/clothes से फैलता है; household contacts का simultaneous treatment जरूरी है. 17
Permethrin कैसे और कब लगाएँ?
Permethrin 5% cream: रात में गले से नीचे पूरी body पर लगाएँ, 8–14 घंटे बाद धो दें; close contacts को भी treat करें; repeat if necessary after 7 days per guideline. 18
Ivermectin कब उपयोग करें?
Oral ivermectin (200 μg/kg) used for classic scabies (two doses 7–14 days apart) and as part of crusted scabies regimens; contraindicated in pregnancy and used cautiously in small children — consult specialist. 19
References (authoritative sources)
- CDC — Clinical Care of Scabies. 20
- World Health Organization — Scabies fact sheet & MDA guidance. 21
- CDC — Crusted scabies overview. 22
- PubMed / Systematic reviews on Demodex & topical ivermectin/tea tree oil. 23
- Mayo Clinic — scabies diagnosis & treatment patient info. 24
- Primary Care Dermatology Society (UK) — scabies guidance (permethrin preference and pregnancy notes). 25
- RIVM / Health Agencies — permethrin application instructions & public health control. 26