Scabies — Burrows + Pruritus

A 7-year-old boy from rural Maharashtra presents with intense itching that worsens at night, causing significant sleep disturbance. On examination, the structure marked **A** in the diagram — linear burrows — is visible on the web spaces of his fingers, wrists, and axillae. His mother reports that two other siblings have developed similar symptoms over the past 3 weeks. Based on the pathognomonic finding at **A**, what is the causative organism responsible for this condition?