What is the recommended treatment for recurrent scabies?

Treatment of Recurrent Scabies

For this elderly patient with recurrent scabies after previous ivermectin treatment, prescribe permethrin 5% cream applied to the entire body from neck down (including scalp given his age and recurrent nature), left on for 8-14 hours, then washed off, with a mandatory second application 7-14 days later. 1, 2

Why Permethrin Over Repeat Ivermectin

• Permethrin 5% cream is the first-line treatment recommended by the American Academy of Dermatology and CDC for scabies, and should be prioritized when oral ivermectin has already been tried without sustained success 1, 2
• The patient received a 14-day course of ivermectin previously with only temporary improvement, suggesting either treatment failure, reinfection from untreated contacts, or inadequate environmental decontamination 1, 3
• Permethrin has a more rapid onset of action compared to ivermectin, which may provide faster symptom relief for this symptomatic patient 4

Critical Application Instructions to Prevent Treatment Failure

Application technique is the most common reason for treatment failure - ensure the patient understands these specific steps: 1, 5

• Apply to ALL skin surfaces from neck down, including under fingernails, between toes, in body folds, and the genital area 1, 2
• In elderly patients, also treat the scalp, face, and neck - these areas are commonly affected in older adults and immunocompromised patients 5, 6
• Leave cream on for the full 8-14 hours (overnight application is practical) 1, 2
• Mandatory second application 7-14 days later to address newly hatched mites from eggs that survived the first treatment 1, 3

Addressing the Root Cause of Recurrence

The return of symptoms after initial improvement strongly suggests one of these failures: 1, 3

• Untreated close contacts - all household members, caregivers (including the wound care provider), and close contacts from the past month must be treated simultaneously, even if asymptomatic 1, 2
• Inadequate environmental decontamination - all bedding, clothing, and towels must be machine washed and dried on hot cycle, or dry-cleaned 1, 2
• Items that cannot be washed should be sealed in plastic bags for at least 72 hours (or 2 weeks to be rigorous) 1, 5
• The wound vac dressing and any fabric components should be changed after treatment 1

Special Considerations for This Patient

This patient has multiple risk factors that require attention: 1, 2

• Diabetes with poor glycemic control (readings up to 300 mg/dL) increases risk of treatment failure and secondary bacterial infection 1
• Active wound with wound vac creates additional fomite risk and potential for secondary infection 1
• Multiple comorbidities and polypharmacy - permethrin is safe with his current medications and has minimal systemic absorption 1, 7
• Avoid lindane in this elderly patient with multiple comorbidities due to neurotoxicity risk, especially given his diabetes and potential for compromised skin barrier 1, 2, 3

Managing Expectations About Symptom Resolution

• Pruritus and rash may persist for up to 2 weeks after successful treatment due to hypersensitivity reaction to dead mites and their debris 1, 2, 3
• This does NOT indicate treatment failure and should not prompt immediate retreatment 1, 3
• Consider short-term oral antihistamines or topical corticosteroids for persistent pruritus after treatment 1

Follow-Up Plan

• Reevaluate in 2 weeks after the second permethrin application 1, 3
• If symptoms persist beyond 2 weeks or worsen, consider: 1, 3
  • Combination therapy with both permethrin AND oral ivermectin if simple scabies treatment continues to fail 1
  • Evaluation for crusted (Norwegian) scabies, though less likely given the clinical presentation 1, 2
  • Dermoscopy or skin scraping to confirm live mites versus post-scabetic dermatitis 5

Additional Management Issues

Address the blood pressure elevation (154/83 mmHg) - this may be related to discomfort from scabies but requires optimization of his antihypertensive regimen [@General Medicine Knowledge]

Provide new glucometer as requested to improve diabetes monitoring and identify patterns contributing to hyperglycemia [@General Medicine Knowledge]

Evaluate the persistent cough - while the patient attributes it to a cold, consider medication-induced cough from ACE inhibitor (though he's on losartan, an ARB), GERD exacerbation despite pantoprazole, or other pulmonary causes given his cardiovascular history