A 32-year-old woman presents with intense itching for the past 3 weeks, worse at night. She has multiple burrows on her wrists, interdigital spaces, and lower abdomen. Her 6-year-old son and husband also have similar symptoms. Dermoscopy shows the characteristic 'delta wing' or 'jet with contrail' sign. What is the most appropriate first-line treatment for this patient and her family?

Explanation

## Diagnosis and Management of Scabies ### Clinical Recognition **Key Point:** The combination of intense nocturnal pruritus, characteristic distribution (wrists, interdigital spaces, abdomen, genitals), burrows on dermoscopy, and **household transmission** (son and husband affected) confirms scabies. ### First-Line Treatment **High-Yield:** Permethrin 5% cream is the gold standard first-line treatment for scabies in most populations, including children and pregnant women. #### Permethrin 5% Cream — Standard Protocol - **Application:** Apply to entire body surface from neck downward - **Duration:** Leave on skin for 8–14 hours (overnight application is typical) - **Repeat:** Apply again after 7 days to catch newly hatched mites - **Advantages:** - Safe in children (>2 months) and pregnancy - Low systemic absorption - High efficacy (95%+) - Kills mites and eggs ### Family and Close Contact Management **Clinical Pearl:** All household members and sexual contacts must be treated simultaneously, even if asymptomatic, to prevent reinfection. Fomites (bedding, clothing) should be washed in hot water. ### Comparison of Scabies Treatments | Agent | Formulation | Frequency | Notes | Limitations | |-------|-------------|-----------|-------|-------------| | **Permethrin 5%** | Cream | 2 applications, 7 days apart | First-line; safe in children | Rare contact dermatitis | | Sulfur 5–10% | Ointment | Daily × 7 days | Safe in infants, pregnancy | Messy, slow-acting, odor | | Ivermectin | Oral | 2 doses, 7 days apart | Useful in institutional outbreaks, crusted scabies | Teratogenic; not for children <15 kg | | Crotamiton 10% | Cream | 3 consecutive nights | Alternative if permethrin unavailable | Less effective; requires longer application | **Mnemonic:** **PECS** — **P**ermethrin (first-line), **E**very 7 days (repeat), **C**ontacts treated (family), **S**kin from neck down. ### Why Permethrin is Preferred Here 1. **Household transmission** → need safe agent for children → permethrin ideal 2. **Efficacy** → 95%+ cure rate in single course 3. **Safety profile** → minimal systemic absorption, safe in pediatric population 4. **Compliance** → simple two-application schedule [cite:Irvine 3e Ch 8]