Epidemiology and pathogenesis of scabies

Background: Scabies infestation is known to be more common in hot and humid climates, areas with low medical accessibility, and households with many family members living together. Recently, the number of collective residence facilities for chronic patients and elderly people has increased in developed countries. Furthermore, mass infections are occurring in these facilities. Current Concepts: The cause of scabies infestation is Sarcoptes scabiei var. hominis. It takes about 9 to 15 days for an egg to hatch and grow into an adult mite. Adult mites have an oval body and four pairs of legs. Female mites lay eggs and live for 4 to 6 weeks. In order to spread, mites from an existing host must transfer to a new host. Therefore, external environments such as temperature and humidity are advantageous for the survival of mites, and the closer the distance to other hosts, the higher the infestation rates. In general, scabies infestation induces T helper (Th) 1 cell-mediated reaction, which can prevent the proliferation of mites to some extent. However, in crusted scabies infestations, Th2 cell-mediated response is mainly induced. This response does not suppress the proliferation of the mites and makes them more contagious. Discussion and Conclusion: It is necessary to keep in mind and accurately know the characteristics of scabies when diagnosing skin diseases. The Korean Society of Dermatology has selected eradication of the scabies infestation as a key project and is actively providing support to group residential facilities such as nursing hospitals.