Scabies:: a ubiquitous neglected skin disease

Scabies has been a scourge among human beings for thousands of years. Its worldwide occurrence with epidemics during war, famine, and overcrowding is responsible for an estimated 300 million people currently infested. Scabies refers to the various skin lesions produced by female mites, and their eggs and scybala that are deposited in the epidermis, leading to delayed-type hypersensitivity reaction. Recent immunological findings such as cross-reactivity with house dust mite allergens and an altered T-helper-1/T-helper-2 pattern contribute to a better understanding of the pathomechanism. Furthermore, progress in molecular biology and cloning of relevant antigens could enable the development of a diagnostic ELISA system and candidate vaccines in the near future. Typical and atypical clinical presentations with pruritus as a hallmark of scabies occur in young, pregnant, immunocompromised, and elderly patients and include bullous and crusted (Norwegian) manifestations as well as those masked by steroid use (scabies incognito). This article reviews scabies management strategies in developed countries and resource-poor communities as well as typical complications, including the emergence of resistance and drug-related adverse events. Other problems such as post-scabies eczema and reinfestation, and newer treatments such as ivermectin are also discussed.