Leeches, maggots and parasitic worms can play healing role

At first blush, most trauma patients told they may become host to a slippery, blood-sucking little worm aren't particularly fond of the notion.

For many, mention of leeches recalls their famous cameo appearance in "The African Queen," with the ever-less prim Katharine Hepburn bravely plucking the slimy suckers off Humphrey Bogart's bare chest.

Still, patients in danger of losing a finger, part of an ear or a piece of scalp quickly warm to Hirudo medicinalis when educated about its near-miraculous ability to reduce swelling and save their body part, says Dr. Nicholas Vedder, chief of the division of plastic surgery at the University of Washington and Harborview Medical Center.

"I've never had a patient say no," says Vedder, who orders leeches from Harborview's pharmacy, where several dozen wriggle around in a fish tank. "Once you understand it's the leech or you lose your finger," he says, patients get downright cozy with their little friends.

Rick Koch, 25, was airlifted from Twin Falls, Idaho, to Harborview on July 19 after a table-saw accident at work removed the thumb and fingers of his right hand. All but one finger was reattached, including his ring finger, which sported a fat black leech.

"I'm game for anything," said Koch, watching as a nurse coaxed a new leech into place after the last one had done its job. He said he hadn't heard about medical leeches before he came to Harborview, but after an all-night surgery to reattach his digits, he was willing to trust his doctors.

The federal Food and Drug Administration, which considers leeches to be medical devices, recently approved a French firm's request to market them in the U.S.; two existing U.S. distributors of medicinal leeches were grandfathered into the rules.

Leeches aren't the only critters to make a medical comeback.

Maggots, who in literature are often associated with decay and death, are considered invaluable by some practitioners in healing certain kinds of wounds.

In January, Dr. Ronald Sherman, a California doctor, received FDA approval to market "medical maggots" for use in removing dead tissue from wounds such as pressure ulcers and nonhealing traumatic or post-surgical wounds. Over the past seven years, Sherman notes, some studies and much anecdotal evidence indicate maggots can help some wounds heal more quickly, helping prevent the need for amputation.

Even parasitic worms, a target of many public-health efforts, may have beneficial effects. In a small study by University of Iowa researchers presented at a prestigious gastroenterology conference earlier this year, 72 percent of patients with inflammatory bowel disease who downed a Gatorade cocktail containing parasitic-worm eggs found symptoms relieved within three months.

Could it be that bugs are sometimes best? Proponents say the proof is in the healing.


Used by practitioners of the healing arts as early as 1500 B.C., leeches have been employed ever since for a variety of medical purposes. In medieval Europe, they were used for general bloodletting on patients suffering from everything from malaise to cancer.

In the 1800s, French physicians alone used a billion leeches a year, according to historians, draining "bad humours" and other ills.

Not surprisingly, leeches got a bad reputation, sort of the crawling version of snake oil.

But over the past decade, with the advent of advanced reconstructive surgery, leeches have, shall we say, crawled back into good repute as an accepted treatment for circulatory difficulties in the microsurgical reattachment of skin or body parts.

Some studies say transplanted tissue flaps are much more likely to thrive when treated with leeches, compared with drug treatment or surgery alone.

In the past year, Vedder estimates Harborview's leeches get credit for saving a half-dozen digits that had been surgically reattached but were in deep trouble.

Typically, what happens is this: Microsurgeons have learned to reconnect small blood vessels so that a finger cut off by a saw, say, can be re-attached. But often, the trauma damages the fragile veins too much to reconnect them, or they're blocked by blood clots when they're attached.

With arteries re-attached, blood comes in, but without working veins, the blood can't go out. That means oxygenated blood can't come in to heal the tissue, which will then begin to swell and turn dark. At that point, the body part is in trouble.

Enter the leech, says Vedder. Leeches, marvelous "devices" that they are, carry all their medications on board in their saliva: an anesthetic, so you won't notice their tiny, sharp teeth; a substance that dilates blood vessels; and finally, hirudin, which Vedder calls the most potent anti-coagulant known to medicine.

"The act of injecting that hirudin is the most important thing it does," says Vedder, because even after a half hour or so when the leech gets full and "kicks back to digest," the anti-coagulant keeps working, so the wound continues to bleed, allowing healing oxygenated blood to flow into tissues.

Vedder and other surgeons who use leeches always prescribe antibiotics for patients, too, because even leeches bred specifically for medical use can't be sterile.

Current interest in leeches revived after a 1985 case in Boston in which surgeons successfully re-attached a boy's severed ear with the help of leeches, said Lisa Darmo, a biologist with Carolina Biological Supply, a distributor for Biopharm.

Biopharm, a Welsh company, is one of two main sources of medicinal leeches in the U.S. The company has about 100 regular hospital customers around the country, mostly trauma centers like Harborview, Darmo said. Harborview sometimes ships "emergency" leeches to other local hospitals, said Drew Edwards, Harborview's director of pharmacy operations.

Darmo's company also gets calls from individual surgeons, mostly plastic or reconstructive specialists with a patient having a sudden problem with venous circulation; her company often provides emergency, same-day delivery of leeches, she said.

"Sometimes they call, they've never used them before, but they're in a tough situation, and they hear from a colleague that this is a viable treatment option," Darmo said.


Sharon Mendez, a registered nurse and certified wound-care specialist at Holy Family Hospital in Spokane, has used maggots in wound therapy for more than 20 patients in and out of the hospital. They're used to remove or "debride" dead tissue in a process called "maggot debridement therapy" or MDT.

"My patients treated with MDT demonstrate pretty spectacular outcomes," says Mendez, who wrote the hospital's protocol for maggot use in wound therapy.

Dr. Loren Engrav, a professor at Harborview in the UW's division of plastic surgery who has used maggots for difficult wounds, says they're a "marvelous debriding device, because they only debride what's dead and not what's alive."

No surgeon, even the most skilled, can excise dead tissue with the precision of maggots, Vedder agrees.

Sherman, the California doctor, has been sharing medical-grade maggots with other medical practitioners for the past decade.

Sherman, who had a lifelong interest in insects, began his focus on maggots during his medical training in the 1980s. "After seeing the miraculous results, I have continued to do everything in my power to help others who want to try maggot therapy," he said.

In a journal article in 2002, Sherman noted that there are no formal guidelines for the medical use of maggots.

"Practitioners' treatment decisions have been made primarily on the basis of available medical literature, personal experience, and sheer desperation."

One patient who became a believer is Pam Mitchell, an Akron, Ohio, diabetes patient who got a cut that wouldn't heal on her foot about five years ago. A break in the skin on her other foot led to another nonhealing wound. Many rounds of antibiotics later, she had two toe-tips amputated. Later, an infection in her heel became so bad doctors told her foot amputation would soon be her only option.

"Then by chance I was talking to a co-worker who had seen maggot therapy on the Learning Channel and how well it worked in Europe," she said, and she persuaded her doctor to try it. "My orthopedic surgeon was amazed," said Mitchell, whose foot now has only a small scar.

Engrav, at Harborview, stopped using maggots about a decade ago because of the disconnect between the hospital environment and maggots.

It's the "yuck" factor, Engrav said. On a scale of 0 to 10, "a leech is maybe a 3 or a 4. But a mass of crawling maggots is maybe a 9."

Sherman, in a journal article, noted "patient anxiety," as well as anxiety among nursing and medical staff, which he says can be addressed by education. "We have not found any successful methods of relieving the anxiety of hospital administrators," he conceded.

For patients with a nonhealing wound, says Mendez, the Spokane nurse, the "yuck" factor is relative: "What's yuckier than an ugly, smelly wound on your body that's affecting your life and health?" she asks. "Or the doc saying 'I'm gonna have to amputate?' "

In some cases, even 48 hours of treatment can do "amazing things," Mendez says. "And when you take that dressing off and see a clean, healthy, healing wound that completely turns a person's life around — it's great."

Carol M. Ostrom: 206-464-2249 or costrom@seattletimes.com


International Biotherapy Society:

Biopharm (leeches):

Leeches USA:

King County's leech page:

Dr. Ronald Sherman's "Maggot Therapy Project":

Worm therapy for inflammatory bowel symptoms:

Leeches and maggots and worms, oh my!

Yucky though they may be, these critters are very good at what they do best. In fact, advocates say, for certain jobs, they're the best alternative modern medicine can offer.


There are hundreds of varieties; the most common in microsurgery is Hirudo medicinalis, a 5-inch dark-skinned native of southeast Asia and Europe. Primary use is to relieve congestion in a re-attached body part or flap of skin such as a lip, eyelid, ear, piece of scalp or finger.

One leech can suck 5-15 ml of blood (about six to 10 times a leech's body weight), usually within 15 to 60 minutes.

When it's "full," and detaches, the bite site may bleed for 10 hours or more, releasing as much as 150 ml of blood.

A leech secretes three main substances: hirudin, which keeps blood from clotting; a vasodilator that relaxes smooth muscles of blood vessels; and a morphinelike substance that usually makes the bite painless.


Specially raised, disinfected maggots, typically the larvae of Lucilia (or Phaenicia) sericata, the green blowfly, help clean wounds such as pressure sores and diabetic ulcers. They eat only dead tissue.

First medical use was after World War I military surgeons noted better healing in maggot-infested wounds.

In 1934, maggots were used by an estimated 1,000 American, Canadian and European surgeons.

In 1940s, after antibiotics came into widespread use, maggots fell out of favor.

Dr. Ronald Sherman, whose maggots recently were cleared for medical use by the FDA, has shown in studies that maggots are more effective than conventional treatment in excising dead tissue and reducing wound size in nonhealing foot and leg ulcers in diabetics.

The number of practitioners or centers using maggots has swelled from fewer than a dozen in 1995 to almost 1,000, including more than 70 U.S. practitioners, says Sherman, one of two U.S. suppliers.

Parasitic worms

Gastroenterologist Joel Weinstock of the University of Iowa noticed there was more inflammatory bowel disease when public-health sanitation efforts improved, yet it was nearly nonexistent in less-developed countries where intestinal parasites are common.

He theorized that the human immune system evolved to cope with a gut full of worms, and without them, it can become hyperactive, triggering an autoimmune response.

Over 24 weeks, he studied 29 patients with autoimmune inflammatory bowel diseases, such as Crohn's disease and ulcerative colitis. Every three weeks, they drank a cocktail containing 2,500 eggs of the pig parasite Trypanosoma suis.

By the 12th week, the disease was in remission for 21 of the 29 patients.

Sources: Kowalczyk, "A low-tech approach to venous congestion," RN, Oct. 1, 2002; University of Michigan Museum of Zoology Animal Diversity Web (animaldiversity.ummz. umich.edu/site/index.html); Sherman, "Maggot Therapy for Foot and Leg Wounds," Lower Extremity Wounds, 1(2), 2002, Sherman, "Maggot therapy for treating diabetic foot ulcers unresponsive to conventional therapy," Diabetes Care, Feb. 2003; Knight Ridder News Service.