Treatment of Norwegian (Crusted) Scabies
Norwegian scabies requires aggressive combination therapy with both topical permethrin 5% cream applied daily for 7 days then twice weekly until cure, plus oral ivermectin 200 μg/kg on days 1,2,8,9, and 15. 1
Why Combination Therapy is Essential
Norwegian scabies is fundamentally different from ordinary scabies and demands a more intensive approach:
- The mite burden is massive (thousands to millions of mites versus 10-15 in typical scabies), making single-agent therapy inadequate 1
- The condition is far more contagious than typical scabies and occurs predominantly in immunodeficient, debilitated, or malnourished patients 1
- Single-dose topical scabicide or oral ivermectin alone results in substantial treatment failure according to both the American Academy of Dermatology and CDC 1
Specific Treatment Protocol
Topical Component
- Apply permethrin 5% cream daily for 7 consecutive days, then continue twice weekly until discharge or cure 1
- Apply to all areas of the body from neck down, including under fingernails and all body folds 1
- Do NOT use single-application permethrin as recommended for ordinary scabies—this will fail 1
Oral Component
- Ivermectin 200 μg/kg on days 1,2,8,9, and 15 1, 2
- Take with food to increase bioavailability and epidermal penetration 1
- The multiple-dose schedule addresses ivermectin's limited ovicidal activity and the massive mite burden 1
- Do not skip the oral component—topical therapy alone is insufficient given the mite burden and thick crusts 1
Critical Treatment Pitfalls to Avoid
- Never use lindane in Norwegian scabies patients, as they are often immunocompromised or debilitated, making them vulnerable to neurotoxicity 1
- Failure to use combination therapy is the most common cause of treatment failure 1
- Not treating all close contacts simultaneously leads to reinfection 1, 2
Contact Management and Infection Control
- Examine and treat all persons with close personal, sexual, or household contact within the preceding month, even if asymptomatic 1, 2
- Isolate the patient during treatment, as Norwegian scabies is highly contagious and can cause nosocomial outbreaks 3
- Decontaminate all bedding, clothing, and towels by machine washing/drying with hot cycles or dry cleaning 1
- Items can alternatively be removed from body contact for at least 72 hours 1
- Fumigation of living areas is unnecessary 1
Follow-Up Expectations
- Pruritus and rash may persist up to 2 weeks after successful treatment—this does not indicate treatment failure 1, 2
- Reevaluate at 2 weeks and consider retreatment only if symptoms persist or live mites are observed 1, 2
- Prolonged surveillance is required for eradication, particularly in institutional settings 4
Special Considerations for High-Risk Patients
- Immunocompromised patients require closer monitoring as they are at increased risk for treatment failure 1
- Norwegian scabies can lead to secondary bacterial infections, sepsis, and multi-organ failure if not treated aggressively 5
- In cases with severe plaque formation, surgical debridement may be complementary to standard treatment 6