BLOODSUCKERS
JOHN COLAPINTO. The New Yorker. New York: Jul 25, 2005.

 

On a recent morning in Hendy, a tiny, rain-drenched town in southern Wales, a young man named Ioan Cunningham appeared at Biopharm, a commercial leech farm housed in a long, low brick building that sits on thirty-five acres of marshland near the center of town. Cunningham plays rugby for the local team, the Llanelli Scarlets, and during a match two days earlier he had slammed into another player and suffered a cauliflower ear. When the ear did not improve--it remained purplish-black and had swollen nearly inside out--the team's doctor sent him to Biopharm. There he was greeted by Carl Peters, the farm's thirty-year-old assistant manager, who pronounced the injury "one of the worst cauliflower ears I've seen." He invited Cunningham to take a seat in the small front office, and went down the hall to fetch some leeches.

Peters entered a large windowless room maintained at eighty-two degrees Fahrenheit. Dimly lit and quiet, the room contained sixty-seven aquariums stacked on steel racks that stretched from the floor to a height of six feet. From a shelf in an adjoining room, Peters removed a plastic jar filled with purified water and about ten dark, ribbonlike creatures. He lifted the lid and peered inside. Five hundred years ago, Leonardo da Vinci, in a sketch, attempted to capture the mesmerizing rippling motion with which leeches propel themselves through water. Peters was merely trying to identify the fastest swimmers--"Since those are hungriest," he said.

He darted his bare hand into the jar and, as though he were plucking a cigarette from an ashtray, seized a leech between his index and middle fingers and flicked it into a small plastic container. He repeated this feat, then clipped on the lid and carried the wriggling leeches back to the office where his patient sat, stoically waiting. Peters placed some cotton wool in Cunningham's ear canal--leeches can move with startling speed and are apt to crawl into any available orifice--and, with a pair of plastic forceps, brought one of the animals to the injured ear. The leech recoiled, curling back against the forceps' tongs. The second leech reacted similarly. "It's your hair products," Peters told Cunningham. With a wet cloth, he cleaned the hair around the ear and tried again. This time, the leech brushed its head against the bruised flesh and latched on.

The leeches used for medicinal purposes are parasites, typically between two and four inches long, with disklike suction cups at either end of their bodies. They subsist on the blood of mammals, and have evolved over millions of years to take their meals with efficiency and stealth. At the center of a leech's head sucker are three jaws, arranged in a Y-shaped pattern and each containing about a hundred teeth, which penetrate the skin in a sawing motion. An anesthetic in the leech's saliva is pumped into the bite from minute ducts between its teeth. This is what had started to happen to Cunningham. "I felt a slight prick, then nothing," he said. As the leech began to suck, it released several other substances into his ear: a powerful anti-coagulant, which prevented his blood from clotting; a vasodilator, which opened his vessels, helping to increase blood flow; and a spreading factor, which moved these chemicals quickly into tissue farthest from the bite, liquefying any hardening blood. The leech grew bloated as it dangled from the ear, expanding to roughly seven times its normal size until it resembled a plump, glistening cigar. After twenty minutes, the animal released its jaws, dropped into the container Cunningham held open beneath it, and lay sated and immobile.

Cunningham was feeling better, too. His ear was noticeably pinker and smaller, but the full effect of the leeching would become apparent only over time, as his wound, infused with the animal's anti-clotting enzymes, continued to bleed heavily for the next few hours. "Come back in two days for one more leech and you'll be right as rain," Peters told him. Then he doused the leech in a weak solution of alcohol to knock it out--"More humane," he said--followed by a strong solution of alcohol, which killed it. He placed the dead leech in its container in the trash can beside his desk. "Think about it," he said. "It's like a dirty needle--that can walk."

Biopharm is one of the world's largest commercial leech farms. (There are three others, in France, Germany, and Russia.) Last year, Biopharm sold approximately fifty thousand leeches, most of them to hospitals in Britain and the United States. Once symbols of medical ignorance and barbarity, leeches are now on hand at many major American hospitals, where they owe their unlikely rehabilitation to a high-tech branch of medicine that emerged in the nineteen-eighties: microsurgery, in which doctors repair tiny blood vessels while peering through a microscope.

Bruce Minkin, a surgeon in Asheville, North Carolina, who performs microsurgery to reattach severed fingers, keeps leeches in a jar of distilled water in his office. "When you're sewing on a finger, it's relatively easy to join up the arteries that pump blood into the digit, because they're big and they've got thick walls," he says. "But it's tougher to connect the tiny veins that drain the blood away from the finger and back to the heart." When veins fail to connect properly, venous congestion--what Minkin calls the "sludging up" of excess blood--can occur. A congested finger will turn blue and cold and, unless circulation is quickly restored, will die.

A hungry leech drinks only about two teaspoons of blood during a typical feeding--not enough to drain a congested finger. The prolonged bleeding caused by the chemicals in the animal's saliva is what makes leeching so effective. Until recently, doctors lanced congested veins, or dripped anti-coagulants into the wound. But none of these techniques work as well as a leech bite, which creates what one expert calls an "artificial circulation," keeping a reattached appendage alive while the patient grows new veins. Last summer, the F.D.A. approved the leech for use as a medical device, making this only the second time that the agency has authorized such a use for a live animal. (Maggots, which can be applied to wounds to consume infected tissue, were approved in January, 2004.) Additional medical uses for the leech may be forthcoming: during the past decade, scientists have isolated enzymes and proteins in the animal's saliva that show promise for the treatment of eye disorders, cardiovascular disease, and osteoarthritis.

There are more than six hundred and fifty documented species of leech, and much of what is known about many of them is the result of research by Roy T. Sawyer, an American-born zoologist, who is Biopharm's founder. Sawyer, who is sixty-two, has studied leeches in more than thirty-five countries, and his three-volume, twelve-hundred-and-fifty-page study, "Leech Biology and Behavior," which was published in 1986, is unrivalled in authority and exhaustiveness. Lorna, Sawyer's wife of thirty-five years, who helps to manage Biopharm, says, "I knew that leeches would always be the first love of his life."

The Sawyers live with their adopted teen-age daughter, Bethany, in a handsome nineteenth-century stucco house on the Biopharm property. Sawyer's office, where he spends most of his time, is in the attic, and is reached through a large room lined with glass-fronted cases containing leech and bloodletting paraphernalia: antique leech jars, lancets, fleams, scarificators, cupping devices, bleeding bowls, and barber poles. (Nineteenth-century "barber-surgeons" not only cut hair but also bled patients, thus the red-and-white striped poles outside barbershops, which represent blood and bandages.) Sawyer's walls are covered with leech-themed prints and paintings, among them murky nineteenth-century oils of bewigged apothecaries, and a garish promotional poster for a 1960 pulp movie, "The Leech Woman." These items constitute a mere fraction of Sawyer's collection, the bulk of which he put on display in 1997 in a building in Charleston, South Carolina, which he maintained as a leech museum. (He closed the museum in 1999, and most of his collection is now in storage.) Sawyer's office is dominated by a desk on which are heaped unfinished manuscripts about aspects of the leech that he has somehow not yet managed to address in his published journal articles on the animal. A vigorous man with graying blond hair, a chiselled, ruddy face, and an unwavering gaze, Sawyer is simultaneously defensive about his chosen field--"By its very nature," he wrote at the beginning of "Leech Biology and Behavior," "a work like this prompts questions such as 'Why study leeches?' "--and self-deprecating. "I've only known one person to read it," he says of his magnum opus. "And he used it for insomnia."

Sawyer was born in southern Virginia, where his father was an administrator at Langley Air Force Base. As a child, Sawyer made frequent trips to the tiny town of Gum Neck, North Carolina, to visit his maternal grandmother, who lived near the Dismal Swamps, which are among the world's most biologically diverse temperate wetlands. Sawyer was six when, during one of these visits, he caught a turtle that had a slimy creature attached to its shell. "My grandmother explained to me that it was a leech," Sawyer says. "We kept it as a pet." Soon, he had a large jar of water filled with leeches. Early on, he recalls, his shadow fell across the jar, and the slumbering leeches instantly sprang to life, lunging at the shadow as if they were piranhas. "That's when I really started thinking seriously about leeches," he says. "How many animals have this kind of behavior? How many invertebrates could be so quiet one moment and so aggressive the next?" At fourteen, while digging in the sand near his grandmother's home, he found a leech attached to his hand. He took it home--it was a species that he had never seen before--and dissected it. He wrote up his observations for a school biology report, his first paper on leeches.

The first member of his family to attend college, Sawyer received a degree in biology from Wofford College, in South Carolina, and a master's in zoology from the University of Michigan, in Ann Arbor. Michigan was "leech heaven," he says, because of the huge numbers and varieties that inhabit the state's ponds and lakes. In 1967, he enrolled at the University of Wales at Swansea, to study for his doctorate under Professor E. W. Knight-Jones, at that time the world's leading authority on leeches. It was there that he met Lorna, an undergraduate majoring in English literature. "He was going to write the definitive book on leeches," she says. "It was his primary ambition in life."

Leeches are found in virtually every kind of habitat--polar oceans, deserts, freshwater lakes, tropical marshes--and Sawyer knows something about all of them, including a species in the Sahara that lives in the noses of camels; one that resides in the anuses of hippopotamuses; a cave-dwelling leech in New Guinea that sucks on the blood of bats; and one that attacks the armpits of turtles. Only one species, however, is considered suitable for medicinal purposes: Hirudo medicinalis, a freshwater leech once abundant in the lakes and streams of Europe, whose highly sophisticated mouthparts make it ideal for feeding on the blood of mammals.

According to Sawyer, the earliest references to medicinal leeching appear in ancient Sanskrit writings by the Indian physicians Caraka and Sushruta, who recommended that leeches be applied to snakebites and boils, and around diseased eyes. For centuries, Asian healers concocted a beverage from dried leeches and water, which they used, Sawyer says, for a variety of complaints, from uterine inflammation to "inflamed nose." Galen, the second-century Greek physician, advocated leeching as a supplement to bloodletting, on the theory that health was maintained through a proper balance of the four humors: blood, phlegm, and yellow and black bile. In the early nineteenth century, the practice became a mania throughout Europe; leeches were prescribed for every human ill, from obesity to nymphomania, colds, asthma, vomiting, consumption, and dysentery.

This period of frenzied use, which peaked between 1820 and 1845, was largely due to the influence of Francois Joseph Victor Broussais, a surgeon for Napoleon's armies. Broussais's enthusiasm for the animal derived from his belief that all disease was caused by inflammation of the gastrointestinal tract; his remedy was to starve patients while aggressively bleeding them through leeching and venesection--opening a vein in the arm. He prescribed the use of as many as thirty leeches at one time, sometimes bleeding patients into unconsciousness. Sawyer calls Broussais an "extremist," whose indiscriminate use of leeches reflected the medical ignorance of the day. Yet some of the leeching treatments no doubt worked, he says, particularly in cases involving inflammation and localized swelling.

In the mid-eighteen-hundreds, some six million leeches a year were used in Paris hospitals alone. Young women waded into lakes and ponds to lure the animals onto their bare legs. According to the nineteenth-century French pharmacist M. C. Femnd (who published a monograph on the leech trade), in the Gironde, in France, each year some twenty thousand horses were driven into marshes to attract leeches, and many bled to death. In the United States, the indigenous species, Macrobdella, is not as effective a bloodsucker as its European counterpart, and during the nineteenth century Americans imported millions of leeches from Hamburg. By the end of the century, they had become extinct in Germany through overcollection.

In England, shortages began much earlier. Wordsworth wrote about a dispirited leech collector in his 1802 poem "Resolution and Independence. " "Once I could meet with them on every side," the collector says mournfully of the leeches that once abounded in his pond. "But they have dwindled long by slow decay / Yet still, I persevere and find them where I may." Other Romantic poets had firsthand encounters with leeches. In 1824, Byron denounced his doctors as "a damned set of butchers" when they insisted on a treatment that included attaching twenty leeches to his brow as a cure for fever. He died a few days later.

The misuse of leeches by nineteenth-century physicians reached a ghoulish crescendo in the case of the Russian writer Nikolai Gogol, who was treated for acute anemia in March, 1852. Vladimir Nabokov, in his book on Gogol, describes the "diabolically energetic physicians" who soused him with cold water and put him to bed with six "plump leeches affixed to his nose." Gogol, he writes, "kept pleading to have the leeches removed: they were dangling from his nose and getting into his mouth."

With Pasteur's discovery of germs, in the mid-eighteen-hundreds, and the publication, in 1892, of William Osler's textbook "Principles and Practice of Medicine," which helped to make germ theory the basis of medical practice, the leech fell out of favor--though it did not disappear from the sickbed. (In 1922, James Joyce, in an effort to halt his advancing blindness, was leeched around one eye, and in 1953 Stalin, dying from cerebral bleeding, was leeched by the physicians charged with keeping him alive by any means possible.) Still, by the time Sawyer began to write "Leech Biology and Behavior," in 1972, his professed goal of rehabilitating the leech as a therapeutic device seemed an eccentric fantasy.

Sawyer's book contains entire chapters on leech feeding habits, skin, mucous glands, connective tissue, pigmentation, foraging behaviors, and muscles. In the course of writing it, Sawyer said, he became convinced that the medicinal use of leeches in the past "was not accidental but instead was based on a high degree of evolutionary adaptation." Or, as he explains in the book's preface, "the leech is a living pharmacopoeia which is the mirror image of human physiology." In 1884, John Berry Haycraft, a British physiologist, had identified in Hirudo medicinalis's saliva a powerful anti-coagulant--the first natural anti-clotting substance ever discovered. It was purified in the mid-nineteen-fifties by Fritz Markwardt, a German scientist, and cloned in 1986. (A drug called hirudin, made from the anti-coagulant, is used to treat patients recovering from heart attacks.) But Sawyer, believing that more than two thousand years of leeching had to have produced some therapeutic benefits, suspected that the leech's saliva contained other healing compounds.

In the summer of 1983, when he completed his book--much of which he wrote in longhand, in an unheated cottage on Wales's Gower Peninsula, while Lorna supported them by teaching elementary school--Sawyer decided to create a "California-style biotechnology company," with the goal of identifying curative chemicals in the leech. That fall, he started Biopharm and began selling leeches in order to raise money for his own research. He financed the business with a bank loan of forty thousand pounds, secured with the only asset he and Lorna had, their cottage.

At first, the couple bred leeches in buckets in their garage. Their main customers were other scientists. The leech has unusually large and easily dissected nerve cells, which are ideal for studying nerve communication. John Nicholls, a neurobiologist at Harvard, mapped the leech's nervous system in the sixties, and his work was carried on by Gunther Stent, at the University of California in Berkeley, with whom Sawyer worked as a research associate for two years in the mid-seventies. As the Sawyers' customer base expanded to include microsurgeons, they were able to move their business to a warehouse in the nearby city of Swansea. But many doctors were resistant to leeching. Sawyer recalls addressing a conference of plastic surgeons shortly after Biopharm opened: "This doctor stood up and said, in a very condescending tone, 'Do you mean that you're starting a business based on the hope that we're going to be buying leeches from you?' " Some physicians argued that poor venous drainage in transplanted tissues indicated a surgeon's lack of skill in connecting veins, and balked at the idea of ceding control of a patient's treatment to a slug.

Biopharm was struggling to break even when, on the morning of August 16, 1985, Guy Condelli, a five-year-old boy who lived in the Boston suburb of Medford, Massachusetts, had his right ear bitten off by a dog. During a twelve-hour operation, Joseph Upton, a reconstructive plastic surgeon at Children's Hospital Boston and a professor at Harvard Medical School, reattached Condelli's ear. Three days later, however, it turned blue-black from venous congestion. The boy was given blood thinners and his ear was lanced, but the organ was dying. Upton had once read an article about the use of leeches to drain congested tissue and, desperate, decided to track some down.

Upton had always been an adventurous doctor. As an Army surgeon during the Vietnam War, he had been posted at a large hospital in Augusta, Georgia, where soldiers wounded in Southeast Asia were flown for treatment. Many arrived with infections. Upton knew that Civil War battlefield doctors had used maggots to remove infected tissue from wounds. (Maggots feed only on necrotic flesh, leaving healthy tissue untouched.) He tried the technique and got splendid results. But when the Army hospital's chief of professional services realized what Upton was doing--some maggots hatched in a soldier's cast--he was threatened with a court-martial. With this experience in mind, Upton refrained from telling his superiors at Children's Hospital Boston about his plan to leech Condelli's ear. "If I had asked around Harvard--are you kidding me?" he says. Eventually, he reached Biopharm by telephone and spoke to Lorna, who drove a consignment of thirty leeches three hours from Swansea to London's Heathrow Airport and put them on a plane to Boston.

Upton attached two of the leeches to the upper helix of Condelli's ear, where the congestion was greatest. Within minutes, the organ began to turn pink, and after a few days it completely recovered. Upton became the first doctor to perform a successful microsurgical reattachment of a child's ear. The story became national news, and Upton began to get calls in the middle of the night from colleagues around the world, asking, "Where do we get the leeches?"

At first, American microsurgeons who used leeches tended to be daring physicians, like Upton. During the past decade, however, leeching has become part of the routine training for reconstructive plastic surgeons. Leeches are rarely used in cosmetic facial surgery, says Jeffery E. Janis, a plastic surgeon at the University of Texas Southwestern Medical Center, since procedures such as eye lifts and chin tucks tend not to cause acute venous congestion. "I've used them in breast reconstruction, on lower-extremity reconstruction, on hand and microsurgery, and scalp replants," Janis says. "You don't want to have to use them, but it's always nice to know that they're there, and it's kind of an ace in the hole."

No living organism can be made completely sterile, however, and the leech's gut contains a digestive enzyme, Aeromonas hydrophilia, that can be harmful to humans whose immune system is weak. Sawyer estimates that one in every two thousand patients contracts a bacterial infection from a leech. At Biopharm, the leeches, which can live for more than a year on a single meal, are starved for at least twelve months before they are sold, in order to reduce the bacteria and insure that the animals will be hungry when they are introduced to a patient. But starvation cannot entirely eliminate the bacteria, so antibiotics are frequently administered to patients before a leeching.

Some patients struggle with what Janis calls "the psychological ramifications" of leeching--particularly in cases of prolonged treatment involving multiple leeches for up to ten days at a time, which may be necessary in order to relieve major congestion in large body parts or tissue grafts. "I spend a lot of time with those patients, knowing that it's a very unusual circumstance for any layperson and even for most medical people," Janis says. "Usually, it's after they've undergone hours and hours of surgery--some nights, we'll be up all night putting on five fingers, or a whole hand, or doing a bilateral breast reconstruction that'll take six to ten hours. At that point, the patients are, like, 'I'm in your hands, I'm in God's hands. Do whatever you want, pull out all the stops.' " Janis and Minkin, the North Carolina surgeon, say that none of their patients have ever refused a leeching. "When it's a choice between having a leech and losing a finger, they always choose the leech," Minkin says.

Profits from leech sales rose during the nineteen-eighties, and in 1990 Sawyer moved Biopharm from Swansea to Hendy. Leeches are fussy, and it took Sawyer years to perfect his breeding technique. "You can spend such a long time feeding them to the right size to lay cocoons," he says. "But if you do something wrong--if you give them a cold shock, a blast of cold air, anything like that, they won't bother breeding, or they won't lay many cocoons, or their embryos will be malformed." He credits Carl Peters, who joined Biopharm fourteen years ago as a teen-ager, with making the farm more efficient. Peters designed Biopharm's unique water-filtration system--which incorporates ultraviolet-light sterilization, carbon filters, and something called "foam fractionation"--and his labor-saving innovations have allowed Sawyer to reduce his staff from ten workers to two. (In addition to Peters, there is a manager, Marian Gower, who has been with the company for eighteen years.)

The farm's breeding room is adjacent to the front office, where Peters and Gower take phone orders, and contains sixty-seven aquariums, each tilted at a thirty-degree angle, the lower end filled with a few inches of water, the raised end lined with a bed of soft sphagnum moss. The leeches--eight to a tank--spend most of their time in the water breeding. Because leeches are hermaphrodites, they can fertilize each other during the act of reproduction. The act itself is low-key: two leeches interlock and lie still. A few days later, a gravid leech will swim up to the dry end of the tank, slither into the moss, and secrete a foamy football-shaped cocoon containing twelve to fifteen infants. The babies stay in their cocoons for eighteen to twenty-five days before they hatch. Hatchlings are notoriously active, and, in the past, when Sawyer allowed them to emerge from their cocoons naturally they ended up all over the room. Peters now controls the process by snipping off one end of the cocoon with scissors and squeezing the pale-pink, wriggling hatchlings into a container, which he seals with a tight mesh fabric.

When the hatchlings are a few weeks old, Peters gives them their first meal: a jelly-like cake of hardened pig's blood, collected from a local slaughterhouse. The hatchlings feed on the blood through the mesh fabric. Full-grown leeches take their meals differently. One morning, I watched Peters drop about thirty adult leeches into a tank filled with water. Then he poured fresh sheep's blood through a funnel into a two-foot length of cellulose sausage casing, tied off the end, and placed the blood-filled sausage in the tank. The leeches swarmed the sausage, latching on in thick clusters, and began to feed. The sausage slowly wilted, and the water blossomed with red gore as the leeches, having completed their meal, detached and floated lazily away.

The biggest leeches are returned to the tilted tanks to become breeders. The others are taken to a cold, windowless room containing eighteen shallow vats, each of which holds purified water and two thousand leeches. Here they remain, unfed, before they are shipped to clients. Nearly every day, Peters prepares several orders of between ten and thirty leeches for hospitals in the United Kingdom, and in the course of a month he gathers about five thousand leeches to be divided among Biopharm's distribution centers in Italy, South Africa, Japan, Korea, and the United States. Since medicinal leeches are an endangered species in Europe (they have never recovered from the aggressive collecting of the nineteenth century and the later draining of their habitats for farmland), they are subject to the Convention on International Trade in Endangered Species of Wild Fauna and Flora, or cites, which allows them to enter this country only in limited numbers.

In the United States, Biopharm's leeches are sold by the Carolina Biological Supply Company, in Burlington, North Carolina, which charges eight dollars per leech--more for same-day delivery. Lisa Darmo, a biologist who is the head of marketing for the company's Live Biology Group, says that she has received requests for leeches from producers of reality shows, including "Fear Factor," on which contestants have eaten the animals. "I always try to talk them out of it," Darmo says. "They never ask if it's O.K. to eat them. They just worry if it's entertaining." (Apart from the slight risk of bacterial infection, eating a leech shouldn't hurt you, she says, "especially if it's cooked.")

By 1990, Sawyer had raised enough money through a combination of grants and loans to subsidize the biochemical research that had prompted him to take up leech farming in the first place. A large room at the facility was converted into a laboratory, and Sawyer began to pay six full-time Ph.D. students to conduct experiments on leech saliva. He was particularly interested in the giant Amazon leech, a near-mythic creature that he had rediscovered nearly a century after its last known sighting.

Sawyer had first read about the giant leech in 1975, in the papers of an obscure Italian naturalist, Vittore Ghiliani, who in 1849 described a species of monstrous leech in the Amazon basin which grows to the length of a man's forearm and feeds on the blood of mammals through a six-inch-long needlelike proboscis that it inserts into its host. Ghiliani brought a specimen to Italy and deposited it at the University of Turin's zoology museum. Fifty years later, a French scientist reported seeing giant leeches in the swamps of French Guiana, and claimed that "a few of these enormous leeches are sufficient to kill a cow or a horse." Sawyer knew of proboscis leeches that feed on fish, frogs, and reptiles, but he had never heard of one that feeds on mammals.

In 1976, while researching leech embryology with Gunther Stent, at Berkeley, Sawyer proposed an expedition to find the giant leech, and, in August of the following year, he set out for the coastal marshes of French Guiana with a team that included a doctor, a lab technician, a chemical engineer, and a reporter for the Los Angeles Times. The group waded barelegged into the water, in the hope of luring the leech onto their flesh. Sawyer later described the trials that they faced in an article published in Natural History: possible attack by "electric fishes," virulent mosquitoes, biting flies, bedbugs, and a vampire bat that tried to squeeze through a window screen into their lodgings. After six days without a sign of the giant leech, the team moved to a new location, closer to the sea. In a marshy area, they found a submerged boat that was mired in vegetation and rolled it over. Something large and dark swam out from underneath. James Bleakley, the chemical engineer, grasped it in his hands. It was the giant Amazon leech: a greenish-brown, eighteen-inch specimen, which he flung onto the grassy shore. Only when Sawyer picked up the leech did he realize that there were hundreds of minuscule hatchlings attached to its belly. Dozens of babies fell off the mother and onto his hands. The Los Angeles Times reporter later described Sawyer frantically calling to his colleagues to help him remove the animals before they started feeding.

During the next five weeks, the team bagged thirty-five giant leeches, many of them juveniles, which they shipped back to California. Sawyer was convinced that the animal's unusual feeding system meant that the chemicals in its saliva were likely to be very different from those of the medicinal leech--or of any other leech. In the early eighties, he formed a research partnership with Andrei Budzynski, a professor of biochemistry at Temple University School of Medicine, in Philadelphia. Budzynski isolated an enzyme from the giant leech's salivary glands which he and Sawyer called hementin. Unlike the chemicals in the saliva of jawed leeches, which produce substances that prevent clots from forming, the hementin in the giant leech's saliva breaks down blood clots after they have formed--an adaptation, Sawyer theorized, of the animal's long feeding tube. "In sucking blood through this long tube, the giant leech has to cope with hematologic circumstances faced by no other animal species on Earth," he later wrote. "It takes about a minute for blood to pass along the length of the proboscis; this is slow enough for platelets to aggregate." Hementin's ability to dissolve clots gave it an advantage over existing cardiovascular drugs, but Sawyer was not able to begin the laborious and expensive process of developing the substance into a patent-worthy drug until he established a research team at Biopharm.

Most of the giant leeches from Sawyer's 1977 expedition had died by the time he started his farm, but he replenished his stock during two subsequent trips to the Amazon. Biopharm's staff tried to re-create the giant leech's tropical environment, including the twelve-hour cycle of equatorial light. Each feeding took a worker fifteen hours, since the leeches had to be tricked into thinking they were sucking on a living host. They were fed cow's blood, which was collected within thirty minutes of slaughter and placed, still warm, inside animal hides. The workers often used cow skin, but rabbit skin was also popular. "I ran over a squirrel one day on the way to work," Peters recalls. "It went straight into the boot." Peters also found that, to encourage the leeches to breed, it helped to stimulate them with gentle vibrations, which he generated by playing soft music--"Bach or a bit of Brahms," he says. The breeding room had to be kept at exactly eighty-six degrees, or the leeches would fail to get into the mood.

In 2000, after harvesting as many chemicals from the leeches' salivary glands as he could, Sawyer allowed the colony to die out. "I have regrets about it, but not serious ones," he said. "You could always do it again if you wanted to." He paused, and added dubiously, "But you'd have to go into the Amazon."

During the nineteen-nineties, Biopharm patented more than a dozen substances from the secretions of six leech species. From the European medicinal leech, the researchers isolated the spreading factor hyaluronidase (an enzyme that breaks down an acid that is a major component of the jelly of the human eyeball), and developed drugs that are currently being tested as treatments for ophthalmologic diseases, including glaucoma. The spreading factor, which Sawyer called orgelase (Welsh for "from the leech"), also dissolved the protective coating around many types of bacteria and enabled the body's immune system to attack the exposed germ--a possible explanation for the leech's prominent role in pre-modern medicine.

Sawyer is no longer the only scientist who believes that the leech has untapped potential as a treatment device. During the past several years, a team of doctors in Essen, Germany, have published a series of papers in leading medical journals, claiming extraordinary success in using Hirudo medicinalis to treat knee pain caused by osteoarthritis. The principal author of the studies is Andreas Michalsen, a German internist and cardiologist. For years, Michalsen had heard about lay healers in rural Germany, Austria, and Switzerland who treated arthritis pain with leeches. In 1999, he took a job at the Essen Clinic, which blends modern Western medicine and ancient healing practices (acupuncture, massage, Chinese medicine), and decided to try leeching his patients. He enlisted the help of his boss, Gustav Dobos, who is also an internist. Their first patient was a man in his nineties who was suffering from severe osteoarthritis of the knees. Michalsen applied four leeches to each knee. Two days later, the patient reported that his pain had vanished. The effect lasted for weeks. Then Michalsen and Dobos designed a small experiment involving sixteen patients. Ten were leeched; six used a topical gel. The control group experienced little improvement, but the leeched patients reported "rapid relief"--and remained free of knee pain at an examination twenty-eight days later. Michalsen and Dobos's study was featured in Annals of the Rheumatic Diseases in October, 2001.

A randomized controlled trial by Michalsen and Dobos involving fifty-one patients, twenty-four of whom were leeched while twenty-seven used the gel, obtained equally promising results. Every patient who was leeched reported not only greatly reduced pain but also increased mobility and function of the knee joints. The effect of a single leeching lasted up to three months in some of the patients and six months in others. The results were published in Annals of Internal Medicine in November, 2003. Since then, Michalsen and Dobos have conducted a larger study, yet to be published, involving four hundred subjects, of whom more than eighty per cent reported a significant reduction in pain.

In March, I visited Michalsen at the Essen Clinic, a sleek fifty-four-bed facility on the wooded banks of the Ruhr. Michalsen, a youthful forty-three-year-old who used to play guitar in a rock band, was trained in Western medicine but says that he became convinced that the use of bloodsuckers by lay healers must be based on sound medical principles. "Leeches were a mainstay of treatment for thousands of years," he said. "People weren't silly. For short periods of time, a crazy system of thought can prevail--I think we Germans know that best." He smiled ruefully. "But not for thousands of years."

From a closet near the reception desk, he took a plastic jar filled with Evian water and several leeches, and entered a room in which there were two hospital beds. On the bed nearest the window, an eighty-one-year-old woman with bright-blue eyes and a face like a dried apple lay on her right side, her hospital gown open to reveal her lower back, hip, and legs. Michalsen told me that she had arthritis in her spine and hip and suffered from severe pain that radiated down her leg. Red pinpoint bruises ran in a line down her left leg, marks left by a leeching five days earlier. The woman told me that before she received leech therapy she had been unable to walk. Michalsen handed the jar to Nina Roy, a colleague, who was examining the woman's back. Roy dropped a leech into a small glass receptacle with a curled lip--a cupping instrument--and placed the cup against the woman's back, imprisoning the leech there. The animal latched on, Roy removed the cup, and the leech dangled free.

The woman appeared not to mind the experience, but in another room, down the hall, a male patient in his late forties tensed at the sight of the leeches and complained of a "burning sensation" as Michalsen attached them to his arthritic right knee. "In German, we have the problem that the word for leech is Egel," he said with a weak smile, "and the word for disgust is Ekel."

In their published papers, Michalsen and Dobos speculate that the anesthetic in the leech's saliva could play a role in relieving their patients' pain. The vasodilators and anti-inflammatory enzymes, which penetrate deep into the joint with the help of the spreading factors, might also account for some of the analgesic benefits--and its long duration. The doctors believe that their results have been too consistent to be ascribed entirely to a placebo effect--an explanation offered by Marc Hochberg, an expert on osteoarthritis, who is the head of the division of rheumatology at the University of Maryland School of Medicine.

In an editorial that Hochberg wrote to accompany the Essen team's study in Annals of Internal Medicine, he pointed out weaknesses in the experiment: researchers knew which patients were leeched and thus were vulnerable to expectation bias; the patients knew which treatment they were receiving--it's impossible to administer a placebo-control leech bite--and this may have colored their responses; finally, the results were subjective, and based entirely on the patients' own assessments of their pain. Michalsen concedes these problems--and duly noted them in the published articles--but he rejects Hochberg's theory, arguing that a questionnaire filled out by patients before the leeching suggested that those who benefitted most from the therapy were not those who expected the greatest relief. "Besides, I can't imagine that a placebo effect of a single treatment would last several months," he added.

Woodson Merrell, an internist who is the executive director of the integrative-medicine department at Beth Israel Medical Center, in New York, read the Essen doctors' study. This fall, his clinic at Beth Israel, the Continuum Center for Health and Healing, plans to offer leech therapy for osteoarthritis of the knee, one of the first American hospitals to do so. "By nature, I'm a scientific skeptic," Merrell told me. "But I'm also very open to things that work. I think that's where this falls. It's wonderful when things that have been around for hundreds of thousands of years are being validated by modern approaches and research."

The Essen doctors recently contacted George Stefano, who is the director of the Neuroscience Research Institute at the State University of New York at Old Westbury. Stefano has spent twenty-five years researching the effects of morphine in humans and invertebrates. Much of his work has focussed on the possibility that morphine, one of the most powerful naturally occurring painkillers, is produced not only by the poppy plant but also by animals, including humans. Building on research begun in the mid-seventies, Stefano and his team at suny have found morphine in mussels, lobsters, rats, animal parasites, and human tissue. In April, Stefano and his team completed preliminary research on the medicinal leech: they found morphine in its head region, which contains the leech's salivary glands.

When I visited Stefano at his office in Old Westbury, he led me down to the basement laboratory, where his team of researchers conduct experiments on animal tissue. Stefano asked Federico Casares, a Ph.D. candidate, to show me what happens "when you add morphine to cells." On a large-format digital camera, we watched a few seconds of film that Casares had recently shot, of lobster immune cells resisting a bacterial pathogen. "The principle here is that when immune cells are active their shape is irregular, they move about, they engulf bacteria, they clean up the area," Casares said. In people with arthritis, immune cells mistake healthy tissue for foreign tissue and attack it, causing pain. Casares then showed me a slide of the same lobster cells after they had been exposed to morphine. The cells had turned smooth, round, and still, like droplets of water. "In arthritis, the immune cell that is phagocytizing healthy tissue is going crazy!" Stefano said. "You add morphine, look what happens! They're round--inactive!"

Studies of animal morphine are controversial. Critics say that the presence of morphine in animal tissues reflects sample contamination, often through the animal's food supply, since small amounts of morphine occur in substances like lettuce, milk, and hay. Stefano counters this charge with a list of the precautions that his laboratory takes: he and his staff test all the foods that the animals eat, all the microorganisms they are in contact with, and all the lab equipment they use. If other researchers confirm Stefano's finding of morphine in the head of Hirudo medicinalis, it might help account for the animal's apparent ability to reduce arthritis pain.

Sawyer was reluctant to venture an opinion on Stefano's research, saying that he no longer keeps up with the latest developments in leech science. In 1997, he sold a dozen of Biopharm's patents to a large European pharmaceutical company, closed his lab, and went into semi-retirement. He still collects leech memorabilia (he recently bought at auction a rare Max Ernst collage featuring a leech), and continues to conduct research on the history of the leech trade (his recent articles include "The Trade in Medicinal Leeches in the Southern Indian Ocean in the Nineteenth Century" and "A Study in Medical History: Introduction of Medicinal Leeches Into the West Indies in the Nineteenth Century"). He is also completing a book about the swamps of eastern North Carolina, where he encountered his first leech. Years ago, he liked to tell people that "secretions from bloodsucking animals could be to cardiovascular diseases what penicillin was to infectious diseases." I asked him whether he stands by that statement now. "Yes," he replied. "I completely believe that today as much as then."