A 68-year-old man with poorly controlled diabetes mellitus type 2 and chronic corticosteroid use (for COPD) presents with severe, widespread pruritus and generalized erythema with numerous crusted lesions over his entire body, including the scalp, face, and intertriginous areas. He reports symptom onset 2 weeks ago. Skin scraping and microscopy reveal numerous mite burrows and mites at all stages of development. His wife, who is immunocompetent, has no symptoms. What is the most likely diagnosis and the most appropriate management?