The rain forests of South-East Asia represent a biodiversity hotspot of terrestrial leeches, but we have only fragmentary and often anecdotal information on this component of tropical communities. To address the foraging tactics of terrestrial leeches, we studied the vertical distribution of Haemadipsa picta on foliage in a Bornean tropical rain forest. We investigated the links between leech body length and the above-ground height of their ambush positions under natural conditions and in a choice experiment performed under semi-natural conditions. We studied 167 leeches, which varied considerably with respect to body length (4–29 mm). On average, the leeches ambushed at lower heights under natural conditions than under experimental conditions (47.7 cm vs. 67.5 cm), though the heights of ambush positions overlapped considerably. Leeches that chose higher ambush positions under natural conditions consistently chose higher ambush positions in the experiment (Pearson r = 0.29). Under both natural and experimental conditions, leech body length was positively correlated with the height of ambush positions (Pearson r = 0.48); on average, a 1-mm increase in body length corresponded to a 2–3 cm higher ambush position. Our findings suggest that H. picta individuals actively choose hunting locations according to their above-ground height, shifting their ambush sites over ontogeny to higher foliage. We hypothesize that growing leeches might target different prey following ontogenetic shifts in the foraging optima, ultimately decreasing intraspecific competition.

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.

The evolutionary history of leeches is employed as a general framework for understanding more than merely the systematics of this charismatic group of annelid worms, and serves as a basis for understanding blood-feeding related correlates ranging from the specifics of gut-associated bacterial symbionts to salivary anticoagulant peptides. A variety of medicinal leech families were examined for intraluminal crop bacterial symbionts. Species of Aeromonas and Bacteroidetes were characterized with DNA gyrase B and 16S rDNA. Bacteroidetes isolates were found to be much more phylogenetically diverse and suggested stronger evidence of phylogenetic correlation than the gammaproteobacteria. Patterns that look like co-speciation with limited taxon sampling do not in the full context of phylogeny. Bioactive compounds that are expressed as gene products, like those in leech salivary glands, have ‘passed the test’ of evolutionary selection. We produced and bioinformatically mined salivary gland EST libraries across medicinal leech lineages to experimentally and statistically evaluate whether evolutionary selection on peptides can identify structure-function activities of known therapeutically relevant bioactive compounds like antithrombin, hirudin and antistasin. The combined information content of a well corroborated leech phylogeny and broad taxonomic coverage of expressed proteins leads to a rich understanding of evolution and function in leech history.

This is a report of two patients with leech inhalation. The first patient presented with severe attacks of inspiratory stridor, cyanosis and cough of five days duration. He had no fever. Indirect laryngoscopy revealed a black, smooth foreign body between the vocal folds. Lateral soft tissue X-ray of the neck revealed shadow involving the glottic and the subglottic areas of the larynx. Laryngoscopy under general anaesthesia showed a living leech. This was removed and the patient improved.

The second patient presented with difficulty of breathing, dysphagia, and spitting of blood of two weeks duration. Indirect laryngoscopy revealed a brown foreign body in the larynx. Laryngoscopy under general anaesthesia showed a living leech. This was removed by forceps.

A case of severe macroglossia. following intraoral surgery, causing respiratory distress is described. Because conventional therapy appeared inadequate, leeches were used and proved an efficient method of reducing this life-threatening swelling of the tongue.