Although long dismissed as quackery, the medicinal leech has recently made a modern medical comeback and is now being used by doctors to treat everything from reattaching severed fingers and salvaging necrotic tissue to treating potentially fatal circulation disorders.
Picture a four-inch-long carnivorous, hermaphroditic, segmented worm with a sucker on each end and five pairs of eyes. Now picture the bloodsucking parasite starting to burrow into your skin.
While simply imagining the work of Hirudo medicinalis, more affectionately known as the leech, tunneling into your body is enough to make anyone squirm, the alternative of losing a finger or a limb is far less pleasant. “There aren’t many options,” said Ronald M. Friedman, M.D, a plastic surgeon in private practice in Plano, Texas. “For someone whose finger has just been reattached, the choice is brutally simple: ‘We can cut your finger off again or use a leech.'”
According to Naomi Rogers, a History of Medicine professor at Yale University, medicinal leeches have been a physician favorite even before the time of Hippocrates. Thirty-five hundred years ago, the bloodsuckers were used as a cure-all by the Egyptians to treat everything from headaches to yellow fever to hemorrhoids. Writer Mitchell Leslie in an American Chemical Society publication said, “A leech enthusiast might treat tonsillitis, for example, by securing a leech with thread, lowering it into the patient’s throat, and allowing it to feed on the swollen glands.”
When Hippocrates introduced the idea of the four humors – blood, phlegm, black bile, and yellow bile, many thought that the imbalance of the four humors were the cause of all disease, and thus most treatments consisted of draining blood, the dominant humor, to restore balance to the body. Leech therapy became the standard for medical treatment. In fact, the modern word “leech” is derived from the Latin word for “physician.” This practice of bloodletting was later introduced to Rome and remained especially popular throughout the Middle Ages.
With the advent of antibiotics in the 20th century, however, the practice of leech therapy gradually lost favor. Although long dismissed as quackery, the persistent bloodsuckers have recently made a modern medical comeback and are now being used by doctors to treat everything from reattaching severed fingers and salvaging necrotic tissue to treating potentially fatal circulation disorders.
The use of medical leeching in modern microvascular surgery and tissue transfer began when two Slovenian surgeons used the parasites to assist with circulation after a tissue-flap transplantation. Then, in 1985, Harvard physician Joseph Upton used medicinal leeches to successfully reattach the ear of a five-year-old boy. Since then, leeches have been widely used to reduce venous congestion in fingers, toes, ears, and scalp reattachments, as well as to salvage vascularly compromised flaps, or muscle, skin, and fat tissue surgically removed from one part of body to another, and replants, limbs or other body parts reattached after traumatic amputation. Without leeching, blood clots often kill the repaired or transplanted tissue.
Often during reattachment surgery, it is relatively simple to reconnect the larger arterial blood vessels but almost impossible to reconnect the thinner, more delicate venous vessels. This leads to pooling of blood and swelling, which may cut off the flow of fresh arterial blood to the reconnected limb completely. “If we can’t get the vein to remain open after surgery,” said Louis P. Bucky, M.D., a plastic and reconstructive surgeon at the University of Pennsylvania in Philadelphia, “then the patient will run into trouble.” Medicinal leeching drains the local blood and decompresses the pressure within the reattached limb, ensuring blood flow to the reattached tissue until the venous blood vessels can reconnect and survive.
When the leech is brought into contact with a patient, it attaches itself with its suckers, injects a natural anesthetic, and the three jaws of its head sucker slice into the patient’s skin with a sawing motion. The leech’s natural anticoagulant, hirudin, inhibits platelet aggregation and keeps blood flowing, which results in a marked relief of venous congestion. The secretions of one leech can prevent up to half a cup of blood from coagulating for up to 48 hours following detachment. “The idea behind the leeches is to cause blood to ooze so that the body’s own blood supply will eventually take over and the limb can go on and survive,” says Rod J. Rohrich, M.D., president of the American Society of Plastic Surgeons and chairman of the Department of Plastic Surgery at the University of Texas Southwestern Medical Center.
The medicinal leech is also used to ensure venous return when small veins cannot accommodate the arterial blood after digit replantations and transfer flaps. “It’s a time-honored method that works extremely well in the right patients, the right clinical situation, the right application. It’s a living drug therapy,” said L. Scott Levin, M.D., professor and chief of plastic surgery at Duke University Medical Center.
Of course, despite their splendor, leeches are far from a surgeon’s first choice. “We don’t want to use them unless we have to,” said Friedman. “It’s a salvage situation.” However, when small veins do not connect and anticoagulants do nothing to help, the centuries old bloodsucker may be a patient’s only option. A 1996 Meta-Analysis published by the National Review of Medicine reported that medicinal leeches saved 70-80% of grafted tissue that would otherwise have died. “Nothing is as effective as a leech,” according to Donald Mackay, M.D., a Pennsylvania State University College of Medicine professor who has been prescribing leeches since 1988.
On June 28, 2004, the Food and Drug Administration (FDA) cleared the commercial marketing of leeches for medicinal purposes and determined that leeches meet the definition of a medical device. Prior to the FDA’s approval, a 1976 law allowed companies growing medicinal leeches before that year to continue doing so but required newcomers to gain FDA approval. In the agency’s review of medicinal leeches, safety was their primary concern. “You won’t find the type of leeches approved for medical use in a lake, river, or swamp,” said Rudy Rosenburg, owner and vice president of Leeches USA Ltd., one of the world’s largest distributors of medicinal leeches today. “The leeches are raised under optimal conditions in controlled basins and laboratories, and patients are perfectly protected from infection. No cases of leech-borne infection have ever been reported.”
In fact, it seems that the hype of leeches has even caught onto Hollywood as a form of extremely alternative beauty therapy, valuable for detoxification and rejuvenation of the body. Actress Demi Moore, while in New York to promote her film Flawless a few years ago, told US talk show host David Letterman that she is always “looking for the cutting edge of things that optimize [her] health,” and that as part of her body cleansing treatment she went to the leech doctor to “detoxify [her] blood”. Moore, satisfied by the process, said that she intends to go for more sessions in the future. “You first feel worse, then you feel better,” said Moore, “but I’m going back – I only got four leeches and I feel a bit cheated.”
While the effectiveness of leech therapy as a form of beauty treatment is still debatable, the leech’s position as surgeon’s helper seems secure. “Leeches are preadapted to human physiology,” said Roy Sawyer, owner of Biopharm, the world’s largest modern leech farm that supplies tens of thousands of medicinal leeches to hospitals worldwide each year. “The secretions from leech saliva cross the entire spectrum of physiology. Blood clotting, digestion, connective tissue, disease, pain, inhibition of enzymes, anti-inflammation – you name it, the leech has it.”