Scabies presentation for Aiman Allawi.pptx

Scabies presentation

1. Done By : AIMAN ALLAWI AUS YAHYA Scabies

2. Definition Scabies is a highly contagious parasitic skin infestation caused by the mite Sarcoptes scabiei var. hominis . Mite burrows into the skin, where it lays eggs, leading to intense pruritus (itching) and a characteristic rash due to hypersensitivity reaction . 2

3. Epidemiology Affects over 200 million people worldwide annually Common in crowded living conditions, low socioeconomic status , and institutional settings. Outbreaks occur in households, nursing homes, prisons, and childcare centers . No age or sex predilection, but higher risk in: Children Elderly Immunocompromised individuals Sexually active adults (genital scabies)

4. Pathophysiology Transmission : Direct, prolonged skin-to-skin contact (≥15–20 minutes). Rarely via fomites (clothing, bedding), especially in crusted scabies. 4

5. Pathophysiology Life cycle: Female mite burrows into stratum corneum of epidermis (2–3 mm/day) Lays 2–3 eggs per day. Eggs hatch in 3–4 days into larvae. Develop into adult mites in 10–17 days. 5

6. Pathophysiology Immune Response Itching is due to delayed-type hypersensitivity (Type IV) to mites, eggs, and feces First infestation : Symptoms appear 2–6 weeks after exposure Re-infestation : Symptoms begin within 1–3 days due to prior sensitization. 6

7. Clinical Features Classic Scabies Intense pruritus , worse at night Papules, vesicles, and excoriations from scratching 7

8. Clinical Features Classic Scabies Burrows (pathognomonic but not always seen): Thin, S-shaped, grayish-white lines (3–10 mm long) 8

9. Clinical Features Distribution (Key Sites) Common : Web spaces between fingers Flexor surfaces of wrists Elbows Axillae Periumbilical area Buttocks Genitalia (penis, scrotum in males; areolae in females) 9

10. Clinical Features Special Forms Nodular scabies Firm, itchy, red-brown papules or nodules (especially in genitalia, axillae, groin ) — common in children 10

11. Clinical Features Special Forms Crusted (Norwegian) scabies Hyper infestation with thick, crusted scales containing thousands of mites. Seen in i mmunocompromised, elderly, disabled, or neurologically impaired Highly contagious. Often minimal itching due to poor immune response 11

12. Clinical Features Special Forms Infantile scabies Atypical presentation: vesicles, pustules on scalp, face, palms, soles 12

13. Diagnosis Clinical Diagnosis History of close contact with infected person Nocturnal pruritus Characteristic rash and distribution Burrows (if visible)

14. Test Procedure Finding Skin scraping + microscopy Scrape burrow with scalpel, apply mineral oil, cover slip, examine under microscope Mites, eggs, or fecal pellets ( scybala ) – diagnostic Ink test (Burrow ink test) Draw over suspected burrow with pen; wipe off; burrow appears as dark line Visualizes burrows Dermoscopy Handheld device to magnify skin Delta gladiator sign – mite at end of burrow Adhesive tape test Apply tape to burrow, remove, examine under microscope May capture mite or eggs ✅ One positive finding (mite, egg, or scybala ) confirms diagnosis Diagnosis Confirmatory Tests

15. Differential Diagnosis Atopic dermatitis Flexural, personal/family history of atopy, less nocturnal itching Contact dermatitis History of allergen/irritant, localized to contact area Papular urticaria Crops of itchy papules from insect bites; children; seasonal Psoriasis Thick silvery scale, well-demarcated plaques; extensor surfaces Tinea corporis Annular, scaly, central clearing; KOH positive Lichen simplex chronicus Lichenified plaques from chronic scratching; no burrows

16. Management Pharmacologic Treatment All household/sexual contacts must be treated simultaneously First-Line: Topical Scabicides Agent Dose & Application Notes Permethrin 2.5%, 5% cream Apply from neck to toe ; leave on 8–14 hours , then wash off. Drug of choice Safe in infants ≥2 months, pregnancy, breastfeeding. Repeat in 7 days if new burrows appear . Benzyl benzoate 25% (adults) or 10% (children) Apply overnight, wash off in morning . Alternative ; can be irritating. Not for infants or pregnant women .

17. Management Pharmacologic Treatment Second-Line: Oral Therapy Agent Dose Notes Ivermectin 200 µg/kg orally , repeat in 7 days Preferred in crusted scabies , institutional outbreaks. Not for children <15 kg or pregnant/nursing women. Often used with topical therapy . ✅ Combination therapy (e.g., permethrin + ivermectin) is common in crusted or resistant cases.

18. Management Supportive & Symptomatic Care Antihistamines : Diphenhydramine , hydroxyzine , or cetirizine – for pruritus (especially at night) Topical corticosteroids : Low-potency (e.g., hydrocortisone 1%) for residual itching or eczematous changes. Avoid long-term use. Emollients to soothe dry, irritated skin ⚠️ Post-scabies itch can persist for 2–4 weeks after cure due to residual hypersensitivity — does not mean treatment failed.

19. Management Environmental Decontamination To prevent reinfestation: Wash all clothing, bedding, and towels in hot water (≥50°C/122°F) and dry on high heat. Items that can't be washed : Seal in plastic bag for ≥72 hours (mites die without human contact). Avoid close contact until treatment is complete.

20. Management Treatment of Special Populations Group Recommendations Infants & young children Permethrin 2.5% (≥2 months); avoid ivermectin in <15 kg Pregnant/breastfeeding women Permethrin is safe; avoid ivermectin and lindane Crusted scabies Requires aggressive treatment: Oral ivermectin (2–3 doses). Permethrin 5% every 2–3 days for 1–2 weeks. Nail trimming, keratolytics (e.g., salicylic acid. Strict isolation and contact precautions ❌ Lindane 1% is not recommended (neurotoxic; banned in many countries)

21. Prognosis Excellent with proper treatment Symptoms improve within days; mites die within 24–48 hours of effective treatment. Itching may persist 2–4 weeks (post-scabies syndrome). Reinfestation is common if contacts are not treated

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