by Rose George
THAT MOST SINGULAR AND VALUABLE REPTILE1
Six seconds. Perhaps ten. Twelve, if it is cautious or dopey. After that, the jaws will activate, the hundreds of teeth will engage, the leech will begin to eat, and its meal is your blood. Are you wading through a tropical pond in fierce humidity? Have you returned to your guesthouse to find with horror a passenger on your leg? Are you Humphrey Bogart, tugging the African Queen and Katharine Hepburn through a brown river, cursing the “filthy little devils” that cling to you? Possibly (except the last). But you are equally likely to be in a sterile room of a modern hospital, tended to by nurses who attach these bloodsucking animals to you without a shiver. You accept them equally calmly, because it has been explained to you that these leeches may save your breast, or your finger, or your ear, or your life.
Less than half a mile from the busy M4 motorway, in the southwest of Wales, there is a walled entrance off a road whose Welsh name I can’t pronounce, and a small sign saying BIOPHARM. A long and winding driveway passes sheds of unclear purpose and ends in a small yard beyond an imposing cream-colored manor house. The view is unexpected: I can hear the motorway, a distant roar, yet here is a quiet landscape of green fields stretching away with no apparent end. The nation’s only leech production business looks like a health farm. Which I suppose it is.
Biopharm was founded by Roy Sawyer, an American zoologist transplanted to Wales. Its name is as broad and generic as its business is specific: it is one of fewer than half a dozen suppliers of medicinal leeches in the world. My hosts are Sawyer’s daughter Bethany, a young woman with a mild Welsh accent and a stern demeanor who is Biopharm’s manager, and her colleague Carl Peters-Bond, a fair man who is what grandmothers would call “cuddly.” They may revise that when they learn that one of his job titles is “leech-growth technician.” Carl is also a practiced Biopharm guide, as well as a retriever of visitors who, given how little signage there is, must inevitably wander into the narrow corridor and wonder if they are in fact in buildings that house a globally renowned supply of medicinal leeches or in someone’s garage.
The reception room is furnished with a large table, a library of leech-related and zoological books, and several ceramic jars in a cabinet, identified by their ornate lettering spelling out LEECHES. These jars were used by apothecaries who sold leeches and sometimes rented them in the high times of the leech industry, from the beginning of the nineteenth century to the early twentieth, a period known as “leech mania.” The mania was for bloodletting, or “the taking of blood from a person with therapeutic intent,” in one description, which had been used for a few thousand years to cure ailments ranging from headaches to near hangings.2 There was hardly any disease or condition for which bloodletting was not thought useful; it was even used to treat severe bleeding. For most of human history, we have preferred to remove blood, not add it. By the end of the nineteenth century people still believed so powerfully in the force of bloodletting that they “were in the habit of coming to be bled at their own request, just as they now apply to have their teeth drawn.”3 Bleeding was done by opening veins with lancets and knives (and earlier with stones, fish teeth, or whatever could cut4), but a leech was kinder, sucking its blood from the capillaries, not veins, and providing its own natural anesthetic.5 By the twentieth century, bloodletting and leeching had fallen from favor with the rise of better surgery and medicine and germ theory. By then the leech had also been harvested almost to extinction from its natural habitat in most of Britain and across much of Europe. Although leech fans are always hopeful of finding undiscovered populations, the known habitats of the British medicinal leech, now, are wetlands near Dungeness, some ponds in the New Forest, and this building near Llanelli.6
Coffee is served and seats taken and then we wait for three student nurses arriving from Swansea, who are coming for a leech training day and who are lost. Meanwhile: chat. Carl has worked at Biopharm for twenty-four years. He used to work with fish. “Just aquariums, like.” Then he was approached by the leech people on the basis that leeches need tanks too, and he has been at Biopharm ever since. His Welsh accent soothes as Welsh accents tend to do, even when he is talking about creatures that can make you bleed for ten hours and look like slugs and are slimy.
The leech is not a slug. Nor is it a bug, reptile, or insect. Sometimes it is not slimy either. The leech is an animal belonging to the phylum Annelida, a zoological category that includes over fifteen thousand species of segmented bristle worms and 650 species of leeches in the subclass Hirudinea.7 Not all leeches suck blood and not all bloodsucking leeches seek the blood of humans. Many have evolved to have impressively specialized food sources: one desert variety lives in camel’s noses; another feeds on bats. Some eat hamsters and frogs. The Giant Amazon leech, which can grow to 45 centimeters (17.7 inches) long, feeds by inserting a proboscis—like a long, 10-centimeter (4-inch) straw—into its prey.8
The leeches that I have driven several hundred miles to encounter are freshwater, bloodsucking, multisegmented annelid worms with ten stomachs, thirty-two brains, nine pairs of testicles, and several hundred teeth that leave a distinct bite mark.9 Depending on the era you live in, this resembles either a wound made by a circular saw or a Mercedes-Benz logo. Biopharm breeds both Hirudo verbana and Hirudo medicinalis. Until recently, verbana was thought to be the same species as medicinalis, and both were called the “European medicinal leech.” Now we know they are genetically distinct. The medicinalis are northern European by origin; the verbana are more Mediterranean.10 Biopharm also breeds Hirudinaria manillensis, named for its native habitat of Manila but also called the Asian medicinal leech or the buffalo, after its habit of dining on bovines. The European is bred to suck the blood of humans; the Asian is for veterinary use. The buffalo leech is fatter, hungrier, and less picky, used to piercing through hairy cattle legs or bellies. Europeans, more refined as bloodsuckers go, avoid stubble, perfume, hair products, and peculiar skin smells.
Both varieties have two characteristics in common: they inject their host with a local anesthetic so that they are rarely noticed until they have tucked in. Because of this, a leech bite will usually feel like a vague sensation, not a nip or scratch. Once their teeth are engaged, they emit the best anticoagulants known to exist, so that their blood meal keeps flowing long after they have stopped feeding, often for up to ten hours. The leech is in many ways a simple animal, but its anesthetic and anticoagulant have yet to be bettered by science. Roy Sawyer has often called the medicinal leech a “living pharmacy.” Only eight compounds in leech saliva have been identified, and there are probably hundreds that are useful. One, discovered by John Berry Haycraft in 1884, was later distilled into what became known as hirudin,11 vastly more efficient as an anticoagulant than man-made heparin, the next best blood thinner. Another is a “potent inhibitor of collagen mediated platelet adhesion and activation.”12 This was isolated after researchers noticed a strange thing: the leech bite made blood flow for hours, but not because of the hirudin. Instead, another substance—which Sawyer named “calin,” Welsh for “heart”—was stopping platelets doing what they were supposed to do, which is to aggregate and form a clot.13 On one patent database, there are ten entries for Biopharm covering antithrombins, hyaluronidase, inhibitors of fibrin cross-linking, protease inhibitors, and heparin-containing formulations.14 Not only is the leech a medicinal treasure chest, but its Mercedes-Benz bite is spectacularly efficient, the tripartite shape much less damaging than a scalpel incision, which can damage tissue. Apart from the bloodsucking issue, it seems to me that the leech is one of the more polite parasites. All in all, it is an astonishing creature, but I still don’t want to pick one up.
The student nurses have arrived with a whoosh of vigor and enthusiasm. They take a moment to enthuse over the musk turtle housed in a tank, a female named Jimmy that to me just looks lonely, then the leech jars and images. In my notebook, I write, “They are almost entirely undisgusted.” And later, “They are going to be really good nurses
.” Then the introductory Biopharm video can begin. It starts with a twenty-year-old scene from the Elizabethan-era Blackadder: Edmund Blackadder is in love and wants a cure. He consults a doctor and the doctor prescribes leeches. The joke is that in Blackadder’s day the cure is almost always leeches. Doctors were called leeches, but because of an etymological coincidence, not for their fondness for prescribing worms. (Leeches were named for the Old English word laece, meaning “worm,” and derived from Middle Dutch; doctors were also called laece, but derived from the Old Frisian laki, meaning “a physician.”)15 This name for physicians lasted until the Renaissance and bequeathed to us such wonderful book titles as Leeching, Wortcunning, and Starcraft of Early England.
The leech is an ancient companion, and the idea of using it to treat maladies occurred to humans thousands of years ago. The body’s ailments were thought to be due to too much blood, among other things. Along with fleams and lances, the leech was an essential tool in the bloodletter’s armamentarium. Babylonians wrote of a striped bloodsucking worm that became “thick with blood” but also described the leech as a daughter of Gula, the goddess of healing. Dhanvantari, the Hindu god of healing, medicine, and Ayurveda, is usually pictured with a jar of leeches in one of his four arms. A wall painting in the tomb of the Egyptian scribe Userhat, thought to date to three thousand years ago, pictures a figure applying leeches.16 The first written record of leeching was probably in the Alexipharmica, a listing of poisons and their antidotes done in hexameter—as all medical literature should be written—by Nicander of Colophon, thought to have lived in the second or third century BCE, but there are leech references in Sanskrit, Persian, Chinese, and Arabic literature.17 The Chinese scholar Wang Chong, wrote Robert Kirk and Neil Pemberton in their fine book Leech, told of a king who accidentally swallowed a leech with his meal but said nothing, not wanting to embarrass his hosts. “Later, the king found himself cured of his chronic affliction. This was, Wang Chong explains, a happy effect of the leech having drawn blood from the site of illness within the king’s body.”18 (Actually a leech in the throat can swell and suffocate you.)
Bloodletting suited humoral medicine, the prevailing dogma for thousands of years. This held that the body was made up of four humors or liquids. The medical historian Hermann Glasscheib called them “the four juices.” A human was only a vessel for these life juices, which were yellow bile, black bile, white phlegm, and red blood. A cold, for example, was due to an excess of the white juice, which was then expelled through the nose and mouth. If someone turned yellowish, there was too much yellow juice. “The body had three doors through which it could evacuate nocive matter,” wrote Glasscheib. “Through the skin in the form of sweat, through the kidneys as urine and through the bowels as feces. But since there were four juices there must also be four exits. The doctors invented this fourth door in the shape of bloodletting.” Hippocrates, Galen, Paracelsus: all the medical celebrities believed in the power of relieving the body of blood. In the Canon of Medicine, the fourteenth-century Persian polymath Ibn Sina (Westernized as Avicenna) devoted considerable attention to bloodletting. It was “a general evacuation,” good for all sorts, medicine that was preventative and curative at the same time. It was useful when “the blood is so superabundant that a disease is about to develop [or when] disease is already present.”19 Different blood vessels served different purposes. Bleeding the veins between the eyebrows was good for long-standing headache, cutting the veins under the tongue—only lengthways, otherwise it was difficult to stanch—was useful for angina or tonsillar abscess. Opening the sciatic vein relieved podagra and elephantiasis; menstrual problems were alleviated by cutting the saphenous vein in the leg. The same vein was good for emptying blood from other organs. He did not recommend that blood be removed from humans aged less than fourteen or more than seventy. Young adults could increase their tolerance for adult-level exsanguination with “small blood-abstractions.”20 It’s easy to scorn this misplaced precision from our privileged position in the twenty-first century. My tonsils were removed as a child because it was standard procedure. I bled for hours into one side of the pillow and then, when the nurse turned it over phlegmatically, the other. Tonsillectomies are now considered old-fashioned and are rarely performed, only forty years later.
Bloodletting was as unquestioned as Band-Aids. Sometimes, it was a job requirement: monks had to be bled several times a year in bleeding houses called seyneys or flebotomaria, either as a sort of general body maintenance or for a more intriguing reason. Monks were supposed to be celibate, and chronic and enforced celibacy was thought to entail a dangerous buildup of semen (retentio semenis), which could lead to blood poisoning.21 Bloodletting avoided blood poisoning.22 Monks didn’t appear to mind and treated bloodletting as a holiday: they were relieved of choir duty and work, a fire was lit in the infirmary, and they got to eat meat.23
By Avicenna’s time, the job of bloodletting could be done by medical men but also by barbers. They were used to sharp instruments, and a papal decree forbidding monks from performing medical tasks meant monastery barbers began to diversify into doing small acts of surgery. This practice spread, so that barbers became instead barber-surgeons and formed a guild. The first barber-surgeon on the registry of the Worshipful Company of Barbers was recorded in 1312.24 The bleeding barber is the reason modern barbers display red and white striped poles: the pole was a stick for the patient to grip; the white stripes were the bandages, the red stripes the blood. The ball on the top was probably a deformation of the blood-gathering bowl.
Liber Albus: The White Book of the City of London, a 1419 rule book published by Lord Mayor Richard Whitington (better known as Dick, and for having a cat), provided instructions for all aspects of city life. As well as looking darkly upon foreigners, who could not be hostelers or sell meat, and forbidding the baking of bread made from bran, the rule book pronounced that no barber “shall be so bold or so daring, as to put blood in their windows openly or in view of folks; but let them have it carried privily unto the Thames, under pain of paying two shillings unto the use of the Sheriffs.”25 Barbers were bloodletters until surgery was established as a profession; there were tussles, and King George II finally put an end to the rivalry by setting up two separate guilds in 1745.26 After this, surgeons did surgery and barbers did what barbers do now, but both could pull teeth.
For two and a half thousand years, if you scratched at any account of illness, bloodletting would come out.
The video has moved on from Blackadder. We are approaching the nineteenth century, when leeching became leech mania. Leeching was accepted enough already that it was applied to royalty. When the Prince Regent of England fell ill in 1816, he was given thirty-six leeches in one go.27 In 1825, Emperor Alexander of Russia caught a fever in the Crimea. The empress urged him to submit to leeching, but he “rejected the proposition with great obstinacy and violence.”28 Only when he worsened did he accept leeches on his head. He died anyway.
It was another ruler who indirectly began the reign of the leechers. A surgeon in Napoleon’s army, François-Joseph-Victor Broussais, became “the most sanguinary physician in history.”29 The Napoleonic Wars, wrote Robert Kirk and Neil Pemberton, meant that “civilian surgeons had been absorbed into the military leaving few with the skills to perform bloodletting via the lancet. Broussais’s brilliance was to present an entirely new system of medicine that sounded modern yet was grounded in a simple, familiar and apparently safe therapy.”30 Broussais’s theory, based on his finding traces of blood in the digestive system on autopsies, was that all illnesses arose from inflammation of the guts. He called these inflammations “phlegmasies” and believed they could all be relieved by bleeding. So could head colds, syphilis, menstruation, flu, cholera, and gout. But he knew that bleeding was dangerous: people would often be bled until the point of “syncope,” or near death. All those opened veins got infected. Broussais thought the leech was a much better idea: even copious leeching did not kill as often as vein openin
g, and leeches were in abundance. Leeching was particularly useful for trauma, “when, for example, a wheel has passed over the body.”31 Inflammation could also be reduced by applying leeches to the anus. “You will in an instant remove a phlegmasie from six inches to a foot wide.”32 (He does not describe this in any more detail, leaving me to wonder what a foot-wide inflammation out of the anus looks like. Briefly.) A toddler needed only one or three leeches, and a woman, fifteen. A grown man should be given sixty in one application. Broussais was a star; his lectures were so notorious, the minister of war (or police, depending which source you believe) once had to close the lecture-hall doors to keep out besieging hordes, and his theories were revered. At the beginning of the nineteenth century, France produced enough native leeches to export them. By 1833, it had to import 41.6 million leeches.33 French doctors by now ordered their patients to be leeched even before they met them, no matter what the trouble. A worm prophylactic.
Where were all these leeches coming from? When they were abundant in European marshes and ponds, leech gatherers would walk bare-legged through ponds to harvest them. The Wellcome Collection in London has a bucolic engraving of Yorkshire women gathering leeches to put them in small barrels, and Wordsworth wrote a poem about a Lakeland leech gatherer, who “roamed from Pond to Pond and moor to moor / Housing, with God’s good help, by choice or chance / And in this way he gained an honest maintenance.”34 It was an honest occupation but not poetic or bucolic. In France, it was known as “blood fishing.”
You would suddenly see a young woman soften and sway, as if she was drunk or dizzy, sometimes slump into the pond, her legs in the mud but her head in the clouds. Her companions knew what this flagging meant: a weakness caused by the insatiable vampirism of leeches. So they would quickly get the stunned girl out of the mud to free her from the slimy parasites.35