Hirudo medicinalis (also called European medicinal leech, medicinal leech or formerly sometimes leech) is one of the medicinal leech species that have been and are still used in medicine for their ability to extract blood, but also for hirudin ( powerful anticoagulant) and other protease inhibitory molecules that they secrete.
This strongly regression species has disappeared from a large part of its natural range of distribution; it is often confused with other species resembling it more or less, to the point that most leeches marketed under this name are actually other species (and most often: Hirudo verbana as has been recently (2007) confirmed by biomolecular analyzes1.
This species may be confused (as was the case until 2005 by taxonomists) with Hirudo orientalis, which is phylogenetically closest to it among all medicinal leeches, but which nonetheless constitutes a species considered today. as distinct.
However, in many countries (including the United States), only the true European medicinal leech is officially authorized for hirudotherapy and it is not certain that other species, even close ones, have exactly the same medicinal properties. For the same reasons, studies of microbiota2, behavioral and biological studies done in the laboratory have conclusions that may have been falsified by a misidentification of the species.