Leech Definition

Posted by Jelio Mir on

The term 'leech' comes from the archaic word for 'healer, physician'. It came from the archaic forms in different languages, which all mean enchanter, healer, physician, counselor'. Leeches are any carnivorous or bloodsucking water or terrestrial worms of the class Hirudea. Leeching refers to placing leeches on the skin, in order to release blood, although the old term of the word literally means 'to cure'. Leeches have been used for as long as human history has been recorded. Records of ancient Egypt, Mesopotamia, Greece, the Mayans and the Aztecs all show the use of medicinal leeches for curing different medical conditions - from headaches to hemorrhoids. They were used by Hippocrates and Herophilos to balance the humours, who believed that an imbalance of the four humours- blood, phlegm, yellow bile and black bile - was at the root of all diseases. The bringing of the leech therapy to the western world is owed to Aelinus Galenus (AD 129-200), a renowned physician, who practiced bloodletting actively and introduced it to Rome. It was the Romans who gave the leeches the name 'hirudo' which is used to this day. Leech therapy remained popular throughout the ages, in all parts of the world, for treating various illnesses. By the mid 1800's the popularity and demand on leeches was so high, that France imported about forty million leeches yearly and England had to buy leeches from the French, since their leech production was insufficient. Leeches were widely used in Asia and the Middle East. With the invention of the antibiotics in the 1930's leeches were abandoned, although they were still used in surgery, to remove stagnant blood from a flap or reattached limb, as well as non-invasive therapy outside hospitals. The use of leeches in Germany and Russia still remains very popular, with Russia being the biggest export of medicinal leeches in the world at this point in time. With the mutating of bacteria and viruses, which makes antibiotics ineffective as time goes by, the use of leeches is slowly regaining it's prominent position in treatment of various illnesses.

Anatomically, leeches are bloodsucking or carnivorous worms of the class Hirudinea, with flat segmented body, up to 20 cm long, with suckers at both ends - an anterior and posterior one. Their body is divided into 33 or 34 segments. They have five pairs of eyes. The anterior end of them has three bladed teeth, which slice through the skin of their host, leaving a Y-shaped mark. When biting, they release anticoagulants and anesthetics into the blood, preventing it from clotting, and other chemicals, which inhibit microbial decay of the blood. Hence, their medicinal properties. The most common leech used for therapy purposes is the Hirudo medicinalis, which is the European medicinal leech.  They suck about 5-15 ml of blood, which is an amount which can last them a whole year. The sucking takes about thirty minutes, until they are fed, more rarely up to two hours.

 Leeches  usually live in freshwater, although there are some marine and terrestrial forms. Their ecosystems range in all of Europe and into Asia. They prefer muddy freshwater pools, which lots of plant growth. Overuse of leeches in the 19th century and the reduction of their natural habitats has contributed to their decline. Also, the stop of horse use for farming has stripped them of their primary food source in their natural habitats. Today the biggest part of the leeches are bred in artificial pools, which grow them for therapy purposes.