Crusted scabies complicated by septic shock: a fatal case report with incidental detection of Sarcoptes scabiei DNA in peripheral blood.

Crusted scabies is a severe form of scabies characterized by massive mite burden and profound immune dysregulation. Secondary bacterial infection is common and may progress to sepsis with fatal outcomes. We report a fatal case of crusted scabies complicated by septic shock in a 58-year-old man with diabetes mellitus and chronic dermatitis. The patient presented with diffuse erythroderma, extensive hyperkeratotic crusts, and deep skin fissures, and several household members had similar pruritic skin lesions. Laboratory investigations revealed marked eosinophilia, extremely elevated serum immunoglobulin E levels, and multiorgan dysfunction. Peripheral blood metagenomic next-generation sequencing identified multiple bacterial pathogens and incidentally detected Sarcoptes scabiei DNA. Despite broad-spectrum antimicrobial therapy, antiparasitic treatment, and intensive supportive care, the patient deteriorated and died. This case highlights crusted scabies as a potentially lethal condition when complicated by severe bacterial infection and underscores the need for cautious interpretation of parasitic DNA detected in blood, particularly in non-invasive ectoparasitic diseases.