History of the Leech Trade in Ireland, 1750–1915: Microcosm of a Global Commodity

In the nineteenth century the medicinal leech Hirudo medicinalis evolved into a lucrative commodity in great demand throughout the western world. In less than a century its trade became big business by any measure, involving tens of millions of animals shipped to every inhabited continent. In this context Ireland is particularly instructive in that it was the first country in Europe to exhaust its supply of native leeches. Concomitantly, it was also the first country to import leeches from abroad, as early as 1750. Being an island with manageable border controls, and a clearly definable medical market, Ireland serves superbly as a microcosm of the leech as a worldwide commodity. Being a relative small country it is possible for the first time to gain a balanced perspective of various economic factors underlying this trade, including supply and demand, exploitation of natural resources, and an evolving network of competitive traders. This paper addresses these and other aspects of the leech trade in Ireland. The principal, and unexpected, finding of this paper is that leeches were unequivocally very expensive in Ireland and became a significant drain on hospital budgets. As such, they found little use amongst the Irish poor. An estimate of several million leeches were imported into Ireland in the nineteenth century, a practice which continued into the twentieth. They were imported initially from Wales and then from France following the defeat of Napoleon, but the bulk came ultimately from Hamburg, via importers in England.