Where did these blood suckers come from?
Medical leeches where first discovered in Europe and as their popularity in medical treatments grew so did their location in the world. Leeches started in England, Scotland, France, Hungary, Ukraine, Turkey, and spread into Iran, Russia, Romania, Algeria, and Egypt. In 1846, 30 million leeches were used in France and 13 million leeches were used in London and Paris in a single year (Rubin 2004). People even created leech farms, shown above, to keep up with the high demand of these invertebrates at the time. Leeches are also held in massive quantities in labs for medical needs.
Habitat
Medical leeches can be usually found in small pools with muddy bottoms and fringed with reeds. They are amphibious freshwater animals meaning that they are capable of living both on land or water. Other animals that share this environment are frogs, toads or newts. Leeches prefer water that is eutrophic, meaning it is high in nutrients (Sawyer 1986). The favorable temperature for leech survival is 20 degrees Celsius, and since shallower water warms up more quickly that's where leeches will be found.