They're Back!

In his Academy Award performance of years past, star Humphrey Bogart hauls himself out of the murky swamp water and onto the deck of the African Queen. He discovers that he is covered with leeches. The horror and disgust he shares with co-star Katherine Hepburn is a reaction to the loathsome little creatures common to mankind since the Stone Age.

Yet these slimy, wriggly little bloodsuckers have enjoyed a medical history that can be traced almost without interruption back to the second century BCE. Bleeding, cupping, and leeching were grouped together under the term "bloodletting," the most common medical practice performed by physicians from antiquity to the late 19th century, a span of 2,000 years. Its popularity began to decline when George Washington died following treatment for a throat infection. He had been bled four times in two days, losing four pounds of blood. Even his close friend and personal physician Dr. James Craik felt bleeding may have been at least partly to blame for Washington's death. "Bloodletting" thereafter began to fall from favor. Recently, however, the indefatigable leech has resurfaced, enjoying approval by the FDA for a handful of medical maladies. Look for jars of these hungry, ugly little things to reappear on pharmacy shelves.

The word "leech" is derived from the Anglo-Saxon word "loece," meaning to heal. The ancient physician was called a leech and his textbook of therapy a leechdom. It is an interesting play on words. Leech is no longer a laudatory term. Today a leech is one who deliberately benefits from another's work without offering anything in return. He is a parasite or "free rider"!

The leech is a freshwater, parasitic, invertebrate belonging to the same phylum as the earthworm. A large sucker at one end attaches to the victim, or patient as the case may be, and makes a small triangular puncture. About one ounce of blood is removed in one hour. The satiated animal then drops off. However, the wound continues to bleed, in distinction to other small wounds in which the blood coagulates rapidly. In 1884 this curious difference led the English chemist Haycroft to discover in the leech saliva one of the earliest anticoagulants, "hiruden!"

Yet even in its heyday, the leech was not for the meek or faint hearted. From an 18th century text: "The appearance of the animal is repulsive and disgusting. Delicate and sensitive persons find it difficult to overcome their repugnance to contact with the cold and slimy reptile." Most of us today can include ourselves in this "delicate and sensitive" group. All of which makes it very difficult to understand the astounding popularity of leeches in 18th and 19th century France. In Paris alone as many as 6 million leechings were performed annually! Hundreds of leech farms were established to meet the demand. The leech was still in short supply. The demand led to some of the most bizarre instruments that can be found in the annals of medical history, the "leech machines." These unbelievable contraptions included the "Heurteloup leech, Damoiseau's terabdella, Sarlandiere's bdellometer, and Tiemann's automatic piston," among others.

Therapeutic bloodletting was largely cast aside by physicians more than 100 years ago. But looking back over so solid a cornerstone in the history of medical therapeutics, one finds a quote by no less noteworthy a physician than William Harvey, the discoverer of the circulation of the blood. In 1628 he wrote, "Daily experience satisfies me that blood letting has a most salutary effect in many diseases." Harvey was a careful observer, but it is still very difficult for the modern doctor to fully comprehend such a statement.

With some misgivings then, let us welcome back the trusty leech. Apparently, there is little that is new under the sun!