Scabies: Diagnosis, Treatment, and Institutional Outbreaks

Overview / Definition Scabies is a cutaneous infestation caused by the mite Sarcoptes scabiei. It is characterized by severe pruritus and a rash that typically appears in intertriginous areas, between fingers, and on other body sites. The condition is highly contagious and can spread rapidly in crowded conditions, such as nursing homes and schools. Epidemiology Scabies affects individuals of all ages and socioeconomic backgrounds, but certain populations are at increased risk: Residents of institutional settings (e.g., nursing homes, prisons) Individuals with compromised immune systems Children and adolescents The global prevalence of scabies is estimated to affect up to 300 million people annually, with outbreaks commonly reported in developing regions. Pathophysiology / Mechanism The Sarcoptes scabiei mite burrows into the stratum corneum of the skin, where it lays eggs and defecates, leading to an inflammatory response. The immune reaction to mite antigens results in intense itching and the development of papules and vesicles. The life cycle of the mite is approximately 30 days, during which it can produce many offspring, contributing to the rapid spread of the infestation. Clinical Presentation Patients with scabies typically present with: Intense pruritus: Often worse at night Rash: Characteristically presents as small papules, vesicles, and burrows, often located in: Interdigital spaces Wrists Elbows Axillae Genital area Secondary infections: Resulting from scratching, leading to potential complications like impetigo Diagnosis / Workup The diagnosis of scabies is primarily clinical, but confirmatory tests can include: Skin scraping: Microscopic examination of skin scrapings can reveal mites, eggs, or fecal pellets. Dermatoscopy: Can help visualize burrows and mites. Clinical criteria: Presence of pruritus and typical rash in the context of an outbreak or known exposure. It is important to consider differential diagnoses such as: Atopic dermatitis Contact derma