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It's Official: Leeches Are Medical Applications

Bloodsuckers win FDA nod for treating skin grafts

TUESDAY, June 29, 2004 (HealthDayNews) -- The ultimate hangers-on are making a comeback: Leeches -- used for centuries to rid the sick of "bad humors" -- received U.S. Food and Drug Administration approval Monday for use in draining blood around skin grafts.

"The FDA is validating current studies, and we applaud the FDA for doing this," said Dr. Rod J. Rohrich, president of the American Society of Plastic Surgeons and chairman of the department of plastic surgery at the University of Texas Southwestern Medical Center in Dallas.

According to an agency statement, the Food and Drug Administration has "for the first time cleared the commercial marketing of leeches for medicinal purposes."

Rohrich noted, however, that plastic surgeons have been using Hirudo medicinalis -- the species most favored by doctors -- in "off-label" applications for decades.

In fact, "medicinal leeches have been used for hundreds and hundreds of years, going back to the Middle Ages," Rohrich said. Even barbers once were allowed to use leeches to draw blood from their ill customers. They'd advertise this service by hanging out their used bandages, which would swirl around a post outside their shop -- hence the origin of the red and white stripes on a barber pole.

Scientific advances caused leech therapy to fall into disfavor at the beginning of the 20th century. But over the past few decades, surgeons began rediscovering the quiet efficiency with which these aquatic worms drain excess blood from serious wounds, such as those created by skin grafts.

When re-grafting amputated fingers or toes, especially, blood can pool around the wound because veins are so damaged they lack the ability to clear the area of blood. According to Rohrich, "if you don't have working veins that take the blood out, the area will turn blue" -- a sign the patient could lose the digit altogether.

Leeches fight this syndrome with a one-two chemical punch. Clamping on with three tiny teeth, they emit a natural anesthetic to minimize any pain involved as they settle in for dinner. They also secrete hirudin, a powerful blood-thinner, which breaks up pooled blood for better evacuation from the wound.

"Hirudin sticks around and causes the wound to bleed for hours and hours," Rohrich explained. "That's actually good, because it allows time then for normal blood vessels to form." Eventually, the area around the graft will develop a normal, functioning venous system.

And the leech? Ingesting many times its own weight in blood, it drops off within a few hours of application. In fact, leech therapy usually means applying teams of leeches, each working different shifts until the wound is completely cleared.

"You put on two or three leeches until they fall off, then you put on two or three more leeches until those fall off," Rohrich said.

The bloodsucking therapy won't drain hospital budgets, though: Sold by special leech farms, the critters cost only about $7.50 each. These farms "grow leeches for just this reason -- these aren't the leeches you'd get from swimming in a swamp," Rohrich said. "They are very clean the way they've been raised, and I've never heard of a [leech-borne] infection in a patient."

A French company that raises leeches for medicinal purposes, Ricarimpex SAS, requested the FDA marketing clearance. According to the FDA, "the firm has been breeding leeches for 150 years. They are handled in a certified facility that tracks each lot."

Before approving leeches as a "medical device," the FDA said, it reviewed the current literature on the safety and effectiveness of leeches as therapy, and also looked over data "on how the leeches are fed, their environment, and the personnel who handle them."

And while the FDA has cleared its use for skin grafts, the lowly leech may have other medicinal gifts for humankind. Last year, German researchers reported that the application of leeches to arthritic knees beat out a popular medication when it came to reducing joint pain. And in a preliminary study, Indian researchers say they've used leeches to treat especially difficult cases of varicose veins. In some parts of the world, they're used to treat black eyes.

Most patients aren't put off by the thought of having the slimy creatures hanging around, either, Rohrich said. While their initial reaction may be "Ugh!" he said, "patients know that the leeches are trying to save their life, so they don't have a problem with them."

More information

To learn more about medicinal leeches, visit the University of Michigan.

SOURCES: Rod J. Rohrich, president, American Society of Plastic Surgeons and chairman, department of plastic surgery, University of Texas Southwestern Medical Center, Dallas; June 28, 2004, U.S. Food and Drug Administration Talk Paper
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