Epidemic Norwegian scabies.

Norwegian scabies is an ectoparasitic infestation by Sarcoptes scabiei, characterized by hyperkeratotic lesions of the hands, feet, ears, and scalp, which contain many mites. An epidemic of Norwegian scabies involved 22 patients in a 25-patient ward of mentally and physically handicapped persons (mostly mongoloids). The pathogenesis of the prolific mite population is unclear, but either a specific immunologic deficit or the inability to effectively eliminate the mites by scratching is a plausible possibility.