What is the most important complication of systemic scabies?

Sepsis is the Most Important Complication of Systemic Scabies

Systemic sepsis is the most important and potentially fatal complication of crusted (Norwegian) scabies, particularly in immunocompromised individuals. 1

Understanding Crusted Scabies

Crusted scabies (Norwegian scabies) is an aggressive form of scabies infestation that typically occurs in:

• Immunodeficient individuals
• Debilitated or malnourished persons
• Patients receiving systemic or potent topical glucocorticoids
• Organ transplant recipients
• Persons with HIV infection
• Patients with hematologic malignancies

Unlike regular scabies, crusted scabies is characterized by:

• Hyperkeratotic plaques containing thousands to millions of mites
• Higher contagiousness than regular scabies
• Potential for reduced or absent pruritus in some cases
• Extensive skin involvement

Progression to Sepsis

The pathway from crusted scabies to sepsis follows this progression:

1. Skin Barrier Disruption: Extensive epidermal involvement with crusting and fissuring
2. Secondary Bacterial Colonization: Initially by Staphylococcus aureus and later by Gram-negative rods from digestive flora, especially Pseudomonas aeruginosa 1
3. Invasive Infection: Bacteria enter the bloodstream through compromised skin
4. Systemic Inflammatory Response: Leading to sepsis, septic shock, and multi-organ failure

Risk Factors for Sepsis in Crusted Scabies

Several factors increase the risk of developing sepsis:

• Immunosuppression (especially corticosteroid use) 2
• Diabetes mellitus 3
• Advanced age
• Malnutrition
• Delayed diagnosis and treatment
• Extensive skin involvement

Clinical Evidence of Sepsis Risk

Case reports demonstrate the serious nature of this complication:

• A 65-year-old male with epilepsy and diabetes developed staphylococcal bacteremia and multi-organ failure despite aggressive treatment 3
• A patient with systemic lupus erythematosus on immunosuppressive therapy developed crusted scabies with secondary bacterial infection 4
• A 69-year-old male on omalizumab and corticosteroids developed crusted scabies and ultimately succumbed to bacterial sepsis 2

Detection of Sepsis in Crusted Scabies

Detecting sepsis in crusted scabies patients can be challenging as:

• Fever may be present due to the scabies disease process itself
• Patients should be monitored for other signs of systemic infection:
  • Confusion
  • Hypotension
  • Reduced urine output
  • Reduced oxygen saturation
  • Increased skin pain
  • Rise in C-reactive protein and neutrophilia 1

Management Implications

To prevent sepsis in crusted scabies:

1. Early Diagnosis: Prompt recognition of crusted scabies, especially in high-risk individuals
2. Aggressive Treatment: Combination therapy with:
   • Topical scabicide (5% permethrin cream applied daily for 7 days then twice weekly until cure)
   • Oral ivermectin (200 μg/kg on days 1,2,8,9, and 15, with additional doses on days 22 and 29 for severe cases) 1
3. Infection Control: Decontamination of bedding and clothing
4. Monitoring: Close observation for signs of secondary infection
5. Targeted Antibiotics: Only when clinical signs of infection are present (not prophylactically) 1

Prevention of Transmission

Preventing transmission is crucial to avoid institutional outbreaks:

• Isolation of affected individuals
• Proper hand hygiene
• Decontamination of clothing and bedding
• Treatment of close contacts

While other complications of scabies exist, including secondary impetigo and post-streptococcal glomerulonephritis, sepsis represents the most immediate life-threatening complication and the leading cause of mortality in patients with crusted scabies.