The history of leeching and hirudin

This historical article traces the practice of leeching from ancient Egypt through its peak in the late 18th and early 19th centuries and chronicles the scientific characterization of hirudin — from Haycraft's 1884 observation of leech saliva's antithrombotic properties, to Jacoby's 1904 isolation and naming of the active anticoagulant, to Markwardt's 1957 crystallization, and finally to genetically engineered production in 1986. For ASH's domain, it provides essential foundational context showing how hirudotherapy and the leech salivary secretome evolved from empirical practice to defined pharmacology, while noting that several biologically active substances beyond hirudin in leech saliva were, at the time of writing, under active investigation. As a historical article, it contains no original experimental data, no clinical outcomes, and no new primary findings; it is a retrospective narrative of previously established milestones and therefore offers background perspective rather than evidence for contemporary practice.