Scabies Treatment and Transmission
For scabies treatment, use permethrin 5% cream applied to all areas of the body from the neck down and washed off after 8-14 hours, OR oral ivermectin 200 μg/kg repeated in 2 weeks. 1
Recommended Treatment Regimens
The 2015 CDC guidelines establish clear first-line options 1:
Permethrin 5% cream: Apply to entire body from neck down, wash off after 8-14 hours
- Most effective, safe, and less expensive than ivermectin
- Preferred for infants, young children, and pregnant/lactating women
Oral ivermectin 200 μg/kg: Repeat dose in 2 weeks (14 days)
- Must be taken with food to increase bioavailability and epidermal penetration
- Limited ovicidal activity necessitates the second dose
- Not for children <15 kg or <10 years old
- One study showed increased mortality in elderly debilitated patients, though not confirmed in subsequent reports
Lindane 1%: Only if patient cannot tolerate recommended therapies or they have failed
- Apply thinly from neck down, wash off after 8 hours
- Avoid in children <10 years, pregnant/lactating women, and those with extensive dermatitis
- Risk of seizures (especially after bathing) and aplastic anemia
- Resistance reported in parts of the United States
Transmission Mechanisms
Scabies spreads primarily through prolonged direct skin-to-skin contact 1, 2:
- In adults, frequently sexually acquired
- In children, usually NOT sexually transmitted
- Close personal or household contact within the preceding month
- The scabies mite (Sarcoptes scabiei var. hominis) burrows into the skin
- Crusted scabies is transmitted MORE easily due to enormous mite burden 1
Environmental Management
Decontaminate bedding and clothing 1:
- Machine-wash and machine-dry using hot cycle, OR
- Dry clean, OR
- Remove from body contact for at least 72 hours
- Fumigation of living areas is unnecessary
- Keep fingernails closely trimmed to reduce scratching injury
Special Situations
Crusted (Norwegian) Scabies
Occurs in immunodeficient, debilitated, or malnourished persons 1:
- Combination treatment required: Topical permethrin 5% cream (daily for 7 days, then twice weekly) PLUS oral ivermectin 200 μg/kg on days 1,2,8,9, and 15
- Additional ivermectin on days 22 and 29 may be needed for severe cases
- Avoid lindane due to neurotoxicity risk with denuded skin
Contact Management
All sexual, close personal, or household contacts within the preceding month should be examined and treated 1, even if asymptomatic.
Common Pitfalls
Rash and pruritus may persist up to 2 weeks after successful treatment 1—this is NOT treatment failure. Symptoms persisting >2 weeks may indicate:
- True treatment failure (medication resistance or faulty application)
- Reinfection from untreated contacts or contaminated fomites
- Cross-reactivity with other household mites
- Allergic dermatitis
Retreatment at 2 weeks should be considered only if live mites are observed or symptoms persist beyond the expected post-treatment period 1.
Institutional Outbreaks
In nursing homes, hospitals, or residential facilities, control requires treating the entire population at risk simultaneously 1. Ivermectin can be considered in these settings, especially if topical scabicides fail. Manage in consultation with a specialist.