Leech therapy


Leech therapy is the use of leeches in the treatment of medical conditions. Leeches are carnivorous or bloodsucking aquatic or terrestrial worms typically having two "suckers," one at each end. The back end suction cup helps the leech to ambulate on dry surfaces, and to attach to its host; the front-end suction cup also contains the mouth with three sharp jaws that leave a Y-shaped bite. The medicinal leech lives in clean waters. Leeches swim free in the water, with an undulating motion. When attached to its host for feeding, the leech remains in place for 30 minutes to 6 hours or more, as it fills with blood. During feeding,leeches can suck 5-15mL of blood, which is several times its own body weight.
The first medical use of leeches is thought to have taken place in ancient India in 1000 BC. The ancient Indians used leeches to treat a wide range of conditions including headaches, ear infections and hemorrhoids. In pre-scientific medicine, the medicinal leech was used to remove blood from a patient as part of a process to "balance the humors" that, according to Hippocrates, must be kept in balance in order for the human body to function properly. The four humors of ancient medical philosophy were blood, phlegm, black bile, and yellow bile. According to this theory, any sickness that caused the subject's skin to become red (e.g. fever and inflammation), must have arisen from too much blood in the body. Similarly, any person whose behavior was strident and sanguine, meaning animated, was thought to be suffering from an excess of blood. By the mid-1800s, the demand for leeches in Europe was so large that the exporter in Germany shipped over 30 million leeches a year.
Leeches (Hirudo medicinalis) historically used to remove "bad blood," are now used extensively by reconstructive surgeons needing to remove stagnant blood from a flap or reattached limb. When the venous blood does not return to the heart, it pools in the wounded area, increasing pressure and preventing fresh arterial blood from entering the area with oxygen and nutrients. The venous blood must be removed and the pressure must be reduced in order to save the flap or limb. The leech is able to do this exceptionally well, because its saliva contains biochemicals including vasodilators, anticoagulants, and anesthetics.
Perhaps the best-known advocate of medical leeches today is Roy Sawyer, an American researcher. Several decades ago, he noted the potential benefits of leech therapy and started one of the world's first modern leech farms. Today, the company BioPharm, which is based in Britain, provides tens of thousands of leeches every year to hospitals in dozens of countries.
In 2001, the mechanical leech was developed, in part by Nadine Connor, a University of Wisconsin at Madison scientist. The device, which looks a little like a small bottle attached to a suction cup, delivers an anti-clotting drug, similar to that in a leech's saliva, to damaged tissue and then gently sucks out as much blood as needed. Unlike real leeches, the mechanical version is insatiable and can remove as much blood as doctors think is necessary.

Related Terms

Blood-letting, hirudin, Hirudo medicinalis, hirudotherapy, mechanical leech, medicinal leech therapy, phlebotomy, Rob Sawyer.