How can scabies mites be treated in humans? - briefly
First‑line therapy uses a topical scabicide, typically permethrin 5 % cream applied to the entire body for 8–14 hours and repeated after one week. Oral ivermectin (200 µg/kg) serves as an effective alternative, especially for crusted disease or when topical treatment fails.
How can scabies mites be treated in humans? - in detail
Scabies is caused by the microscopic mite Sarcoptes scabiei that burrows into the superficial layers of the skin. Effective eradication requires agents that either kill the parasite on contact or disrupt its life cycle.
First‑line pharmacotherapy
- 5 % permethrin cream applied from the neck down (including scalp in infants) and left on the skin for 8–14 hours before washing off; repeat after 7 days.
- Oral ivermectin 200 µg/kg as a single dose, repeated after 7 days; preferred for extensive disease, crusted scabies, or when topical treatment is impractical.
Alternative topical agents
- Benzyl benzoate 10–25 % lotion, applied for 24 hours and repeated after 48 hours.
- Crotamiton 10 % cream, applied nightly for 3 days, then a second course after 7 days.
- Sulfur 5–10 % ointment, left on the skin for 24 hours and repeated daily for 3 days; safe for infants and pregnant women.
- Lindane 1 % lotion, single application; limited use due to neurotoxicity risk.
Dosing considerations
- Oral ivermectin is contraindicated in children under 15 kg and in the first trimester of pregnancy.
- Permethrin is safe for all ages, including neonates, when applied correctly.
- Sulfur preparations are the only option universally accepted for pregnant patients and newborns.
Management of contacts
- All household members and close contacts receive prophylactic treatment, regardless of symptom presence.
- Simultaneous treatment of contacts prevents re‑infestation.
Environmental control
- Wash bedding, clothing, and towels in hot water (≥50 °C) and dry on high heat.
- Items that cannot be laundered should be sealed in plastic bags for at least 72 hours, a duration exceeding the mite’s survival window.
Resistance and treatment failure
- Documented resistance to permethrin and ivermectin is rare but reported; in such cases, combine oral ivermectin with a topical agent.
- Persistent pruritus beyond 2 weeks may indicate secondary infection; evaluate for bacterial superinfection and prescribe appropriate antibiotics.
Special populations
- Infants under 2 months: sulfur ointment preferred; permethrin can be used with caution.
- Immunocompromised patients: consider higher‑dose ivermectin (400 µg/kg) and extended topical therapy.
- Pregnant or lactating women: sulfur ointment or low‑dose permethrin are recommended; avoid lindane and high‑dose ivermectin.
Successful clearance is confirmed by the cessation of new burrows and the absence of active lesions after the second treatment cycle. Follow‑up evaluation should occur 2–4 weeks post‑therapy to ensure complete resolution.