Highly contagious skin infestation caused by the mite Sarcoptes scabiei

Aetiology

• Sarcoptes scabiei is spread by direct contact

Pathophysiology

• A delayed type IV hypersensitivity reaction results in symptoms around 30 days after the initial infection

Clinical features

• It presents with an intensely itchy rash that usually affects the inter-web spaces, flexures of the wrist, axillae, abdomen and groin
• The itch is classically worse at night
• The rash is usually papular or vesicular and superficial burrows may often be seen

Norwegian (crusted) scabies

• Norwegian (or crusted) scabies is where an individual is affected by millions of mites causing a generalised scaly rash - it is seen in immunocompromised patients

Management

• The first line management of scabies is topical permethrin 5%
• Malathion 0.5% should be used 2nd line as there is limited evidence for its effectiveness
• To minimise chance of reinfection it is very important that all contacts, included members from the same household, are treated on the same day