Scabies

Patients with Norwegian (crusted) scabies might describe severe itching (pruritis), especially at night, and could also report a history of exposure to individuals with similar symptoms. Family members or close contacts often have itching, which can be suggestive of scabies. The condition is more frequent in immunocompromised individuals, such as those on immunosuppressive therapies, elderly patients, and those with HIV. These cases can also involve mild symptoms or atypical presentations, making scabies difficult to diagnose without clinical suspicion.

Scabies is often identified by the presence of small, serpiginous (wavy or S-shaped) white lines where mites have burrowed. Affected areas typically include the webs between fingers, the axillae, umbilicus, groin, and genital areas, and in crusted scabies, the lesions may become thick and crusted over with millions of mites present. In some cases, erythematous papules (red bumps) may form due to hypersensitivity reactions, and secondary bacterial infections, such as impetigo, are common due to skin damage from scratching.

First-Line Treatments:

1. Topical Permethrin 5% Cream: It should be applied to the entire body (neck down in adults, full body in infants), left on for 8 hours, and rinsed off, with a second application after one week. Permethrin kills mites and their eggs, but adherence to application instructions is essential.

2. Oral Ivermectin: Often used in cases of scabies resistance, outbreak settings, or patient preference. Ivermectin (not FDA-approved for scabies but widely used) is given once and repeated after two weeks. This method is more practical for large populations due to ease of administration at 200 microgram per kg single dose (under 25 kg: 3 mg, 25-35 kg: 6 mg, 36- 50 kg: 9 mg, 51-65 kg: 12 mg, > 65 kg: 15 mg) plus sulphur 5-20% ointment..

Alternative Treatments:

• Lindane and Precipitated Sulfur: Lindane is used less frequently due to neurotoxicity risks, and sulfur ointment is safer for use in pregnant women and children but has a lower patient preference due to its strong odor.

• Malathion Lotion and Topical Ivermectin: Additional options but less commonly used as first-line therapy.

Treatment for Crusted Scabies:

• Repeated Oral Ivermectin (multiple doses over weeks) may be necessary for patients with crusted scabies, combined with topical keratolytics to soften and remove thickened crusts, allowing medications to penetrate deeper.

• Moxidectin may be effective in patients showing resistance to ivermectin.

Adjunctive Measures:

1. Treat Close Contacts: All household members and close contacts should be treated simultaneously, even if asymptomatic, to prevent reinfection.

2. Environmental Control: Machine-wash bedding, towels, and clothes in hot water (above 75°C) and dry on high heat. Isolate infected individuals in settings like hospitals to prevent outbreaks.

3. Post-Treatment Considerations: Persistent itching post-treatment may occur due to immune responses. Secondary infections like impetigo should be treated with antibiotics if present. For follow-up, videodermatoscopy or dermatoscopy may be used to confirm eradication or detect persistent mites.

Ensuring compliance with the treatment regimen and patient education on hygiene and preventive steps are key to successful treatment and limiting scabies outbreaks.