Dark Banquet: Blood and the Curious Lives of Blood-Feeding Creatures

by Bill Schutt

  Aneurysms can occur for any number of reasons including high blood pressure and arteriosclerosis. In the latter, this “hardening of the arteries” reduces blood vessel elasticity and produces weakened regions of the vessel wall that can bulge under the pressure of the blood carried within it.

  In the days before the discovery of penicillin, aortic aneurysms were a common side effect of syphilis. Regular bleeding of patients with syphilis-related aneurysms was a way of reducing their blood pressure and thus lessening the chance of having their aneurysms rupture.*67

  Bloodletting was also used to reduce the pain of angina pectoris (literally, “strangled chest”). Angina results from an insufficient supply of blood to the heart musculature (usually because of a blockage or constriction of the coronary arteries). Like the pain from a pulsing aneurysm, angina pectoris is a symptom rather than a disease. It’s part of the body’s warning system—telling it in no uncertain terms that something is seriously wrong. Today, vasodilators like nitrates are used to treat angina. They work primarily by increasing blood flow to the farthest reaches of the body (peripheral blood flow), which reduces blood pressure. Studies on the action of these drugs performed in 1970 indicated that therapeutic phlebotomy also lowered pressure within the resting heart.

  Similarly, congestive heart disease is commonly characterized by an increase in blood volume, and the diseased heart has a tough time pumping this blood to the body. In modern times, drugs like diuretics are used to decrease blood volume (basically, more urine results in less plasma). But up until the 1960s, a viable means to achieve the same result was to perform periodic bleeding of the patient. Thankfully, as in the current treatment of aneurysms and angina pectoris, drugs have replaced bloodletting and there are few patients (or physicians for that matter) who would complain.

  But before we get too carried away with the wonders of drug therapy it should be mentioned that there are several conditions that still call for bloodletting.

  Porphyria (from the Greek word for “purple”) is a disease of the blood that results from the faulty production of hemoglobin, which leads to the accumulation of red and purple pigments called porphyrins. For several reasons, it was referred to as vampire disease. This is because in one form (porphyria cutanea tardia), porphyrins concentrate in the skin. When exposed to sunlight, these abnormal pigments cause damage to surrounding tissues, leading to symptoms like severe skin rashes and blistering. These light-activated toxins and the disfiguring damage they cause may have been a source for tales of vampyres and their destruction by sunlight. Additionally, in some forms of porphyria, severe anemia can result in a pale, spectral appearance, and as the gums recede (from lack of oxygen and nutrients), the teeth become more exposed, causing the canines to take on a fanglike appearance.

  In the acute form of porphyria, exposure to certain substances (e.g., alcohol) can trigger severe neurological disturbances—a fact that now appears to explain the “madness” of England’s King George III (the king mentioned in the Declaration of Independence). Starting in 1762, the British monarch began to have bouts of serious health problems. These often began with flulike symptoms, but they soon segued into depression and strange behavior—racing with a horse, pretending to play a violin, and claims that he could raise the dead. In another instance, George III was reported to have talked continuously for twenty-six hours, his speech garbled and repetitive.

  The king’s medical treatment was remarkably similar to that afforded (or inflicted upon) his American contemporary, George Washington. He was bled, blistered, purged from both ends, and cupped.*68 Leeches were also used to draw off presumed excesses of blood. Sometimes the king went years without an attack, but invariably they returned, and in 1811, George III’s doctors certified him to be permanently disabled.

  For many years, researchers were puzzled by the sudden onset of bizarre behavior and strange outbursts that began to affect the king, especially after he’d reached his fifties. In the 1960s, two authors used information from the king’s medical records (including the observation that the monarch’s urine was the color of port wine) to conclude that George III had suffered from porphyria.

  Recently, additional evidence concerning the king’s affliction has come to light. The examination of several strands of King George’s hair revealed arsenic levels that were three hundred times the toxic level. Professor Martin Warren combined this new information with data from the earlier study to conclude that “the madness of King George” was brought on by porphyria but that the monarch’s bizarre behavior was apparently triggered by arsenic contained in the very medications his doctors had prescribed to treat his madness.

  What’s the connection between porphyria and bloodletting? Although drug treatments now exist to alleviate the symptoms of this incurable illness, therapeutic phlebotomy is still employed to reduce blood volume—which decreases the levels of porphyrins in the plasma. This ancient technique has been effective in providing relief from the painful and often mentally debilitating symptoms of porphyria. In fact, therapeutic phlebotomy may have been responsible for George III’s ability to undergo dramatic recoveries from his illness—until his arsenic-laced medications kicked in, that is.

  There are several other conditions where bloodletting is still used as a therapeutic measure to reduce iron levels in the blood.

  Recently, researchers have found evidence that patients suffering from the viral disease hepatitis C respond better to treatment with interferon if they are first bled to induce a mild state of iron deficiency. Interferons are small proteins naturally produced by cells like macrophages in response to a viral attack on the body. The interferons diffuse into uninfected cells where they act as a shield, interfering with the virus’s ability to enter and infect the cell. Since viruses can replicate only within cells whose reproductive machinery they have hijacked, preventing their entry into uninfected cells is a vital part of the body’s antiviral defense. Interferons also attract and stimulate killer T cells that attack cells infected with viruses. Scientists are still trying to determine why lowering plasma iron concentrations through therapeutic phlebotomy increases the efficiency of interferons (which are used to treat diseases ranging from hepatitis B and C to certain types of leukemia and genital warts).

  Bloodletting is also used to treat a specific form of diabetes. Insulin, a hormone secreted in the pancreas, helps to adjust blood glucose levels by enhancing its absorption and use by the body. High plasma concentrations of the iron-containing protein ferritin may damage the cells that secrete or respond to insulin. This leads to a condition called high-ferritin type 2 diabetes (in which elevated iron levels ultimately result in dangerously high blood glucose levels). Studies have shown that insulin resistance in patients with high-ferritin type 2 diabetes improved after three bouts of bloodletting (in which five hundred milliliters of blood was drained every two weeks for a total of six weeks).

  Other conditions still treated by therapeutic phlebotomy include hemochromatosis, in which the digestive tract absorbs too much iron (resulting in an overload of tissue-damaging iron deposited in places like the liver and pancreas), and polycythemia, in which blood cells are produced at an uncontrollable rate. In many instances the only way to treat these afflictions is to reduce the amount of blood.

  Ultimately, then, there are several relatively rare disorders that appear to benefit from treatments involving therapeutic phlebotomy. But when comparing these instances to the fact that historically, bloodletting was prescribed for basically everything, it’s easy to see that although the practice isn’t quite dead it is certainly a medical relic.

  There is, however, a form of medicinal bloodletting that has stood the test of time. Unlike the techniques described thus far, this one utilizes an ancient worm that has been securing blood meals for far longer than its parchment-winged counterparts. Like vampire bats, these creatures do their bloodletting far more efficiently than any technique cobbled together by humans—and recognizing this, Hirudo has been employed m
edicinally since the time of the pyramids. Nearly abandoned as a therapeutic tool in the twentieth century, the leech has undergone career rejuvenation as modern surgeons have recently turned to their ancient ally.

  A skillful leech is better far, than half a hundred men of war.

  —Samuel Butler

  Rulers who neither see, nor feel, nor know,

  But leech-like to their fainting country cling,

  Till they drop, blind in blood, without a blow.

  —Mary Shelley

  6.

  A BEAUTIFUL FRIENDSHIP

  On the Ulanga River, East Africa

  At the start of World War I

  As Humphrey Bogart’s character Charlie Alnutt struggles to haul the African Queen through the reedy tributary that he hopes will lead to Lake Tanganyika, he is utterly unaware (and just as unconcerned) that his movements are producing waves of pressure change in the chest-high water. The waves carry away from his body like the ripples radiating from a pebble someone might have flipped into a goldfish pond.

  Charlie shoots a quick glance over his shoulder. Rosie (Katharine Hepburn) looks worried. “Don’t worry, old girl,” he says with as much cheer as he can muster.

  Rosie’s angular face breaks into a smile, but her body language betrays her. “I’m just fine, Mr. Alnutt,” she says. Her New England accent has a distinctive quaver, but now Alnutt is alarmed at something else in her voice—something even worse than fear. This is more like doubt.

  “Mr. Alnutt, please take care down there.”

  “Sure, Rosie, sure,” he says, giving her a wave. Only after turning away does he snarl at the recurring image of the skinny missionary dame pouring out all of his gin.

  Crazy old broad, he thinks, moving forward once again and wincing as the towrope bites into his shoulder.

  Below the surface of the dark water, Alnutt’s movements have sounded an ancient alarm, and as they have done since before the age of dinosaurs, the prehistoric hunters react instinctively.

  Several resident leeches have been clinging to the reed shafts, which are to them the size of good-sized tree trunks. They hold on using a suction cup located near their tail end, and so their bodies hang free, drifting in the easy current. Combined with their green coloration, this mimicry gives them the appearance of reeds and serves to protect them from the hungry fish and birds that patrol the swamp.

  Mostly the leeches just wait. Time means nothing to them, but with the sounding of a silent, internal alarm, they are instantly driven by a single, mindless directive.

  To a human it can roughly be interpreted as FOOD.

  Over millions of years, natural selection has equipped these leeches with an array of adaptations that make them well suited for a blood-feeding lifestyle. They include several sensory systems that provide a steady stream of information about their environment and the potential predators and prey that move through it. Ten eyespots are arranged in rows near the leech’s head end, but unlike vertebrate eyes, with their complex focusing ability, these photosensors are specialized at detecting movement and sudden changes in light intensity.

  At this distance, between the reeds and Charlie’s boat, the eyespots register nothing out of the ordinary. Instead, each of the leeches inhabiting this small section of swamp feels a slight sensation run down one side of its body. Holding on with their caudal suckers, they extend themselves to full length, then freeze into an alert posture. The leeches hold this position for several seconds, and as they do, their sensory systems become attuned for additional incoming stimuli.

  There. The vibration has come again.

  SAME SIDE

  STRONGER

  The leeches briefly bend their bodies into horseshoe shapes, a position that enables them to store the potential energy that will be released an instant later when they spring away from the reeds that have held them above the mud.

  Their simple brains are unaware that their bodies are covered by hundreds of tiny touch detectors. Nor do the leeches perceive that some of these mechanoreceptors*69 have been activated by the first wave of pressurized water radiating from Charlie Alnutt as he tows the African Queen into their lair.

  Now the free-floating leeches hesitate for a fraction of a second until another wave of disturbed water hits them. Instantly, they are moving in choreographed unison, adjusting their direction so that the waves of sensation become stronger and stronger, hitting them at their head ends rather than their sides.

  Without thought, the hunters begin undulating their bodies faster and faster, converging on the food source from five different directions, like swimmers from some unreleased Esther Williams horror film.

  Five feet away.

  Three.

  There are flashes of movement. An enormous dark shape—and suddenly the leeches are struggling against tidal waves that batter them from all sides.

  Although they cannot register awe (or any other emotion for that matter), this is the largest food carrier that the leeches have ever tracked.

  One foot away.

  The chemical signals grow stronger and the leeches can feel the heat from the food as it moves in a pulsating torrent—close now.

  Inches away.

  One of them batters up against a gigantic moving wall.

  FOOD

  As the leech tries desperately to secure its anterior suction cup, a tremendous wave smashes it away. The creature cartwheels through the turbulent foam, spinning wildly until the jagged tip of a broken reed spears it.

  The skewered leech is thrown sideways. Its muscular contractions are still strong, but now they send the creature into an uncontrolled downward spiral.

  Five other leeches have followed a concentration gradient of chemical cues, finally locating a breach in the impregnable, woven wall. They swarm in, fanning out and using their suckers to secure purchase.

  In the mud below, another hunter stirs. The twelve hundred facets that make up the dragonfly larva’s compound eyes register movement as the wounded leech corkscrews toward it—slower now—a top running out of spin.

  The predator hurtles upward, capturing the broken reed with six powerful legs. The larva’s mouthparts sink into the leech’s body, working with robotic precision to free the meal from its skewer.

  From a gap in the reeds, a two-foot-long perch watches with growing interest and a hunger of its own.

  Inside the impregnable woven wall, the leeches use three sets of chitenous jaws to saw their way through the thin, wire-covered rind that separates them from the food. Waves of peristaltic muscular contraction run down their elongated bodies and within seconds they begin to—

  Five tiny lives blink out in succession. There is no real pain. Just the sensation of feeding…and then…nothing.

  On the deck of the African Queen, Rosie helps Charlie brush off the last of the dead leeches and the salt she’s thrown on them.

  Charlie Alnutt shudders. “If there’s anything in the world I hate, it’s leeches—filthy little devils!”

  Long Island, New York

  September 2006

  As I stepped out of my car, Albert Einstein’s twin brother gave me a friendly wave. “Rudy Rosenberg,” the man said, extending a hand.

  He wore a red-and-white pin-striped shirt and a blue bow tie. His white hair fell in longish corkscrews around his face. I guessed that he was in his midseventies.

  “Let’s go in the back way,” Rudy suggested, stopping at a keypad before punching in the combination. I followed him into a rather plain-looking industrial building around the corner from the Long Island Expressway. I was a bit surprised that the sign out front read “Accurate” and not “Leeches USA.” I guess I’d been expecting something flashier—a stream of blood or at least some suction cups.

  “There are three companies housed here,” Rudy told me several minutes later as I settled into a seat in his office. The room was comfortably cluttered—every inch of space crammed with artwork, books, journals, and memorabilia. “Accurate Chemical and Scientific, Accur
ate Surgical and Scientific Instruments, and Leeches USA.”

  I perked up.

  He looked at me over the top of his wire-frame glasses. “It’s always the leeches that people are interested in.”

  Rosenberg, a Holocaust survivor, began by explaining that leeches were one of the oldest therapeutic techniques known to man.

  “They’ve been identified from Egyptian hieroglyphics, thirty-five hundred years old. In Sanskrit writings from one thousand BC, leeches were described as treatments for snakebites. The Greeks used them for headaches.”

  I knew from my investigation on bloodletting that in the second century Galen had prescribed leeches as a means to reduce “plethoras”—perceived excesses in the volume of blood (one of the four humors)—and that the word leech was actually derived from loece or laece, an old Anglo-Saxon word meaning “to heal.”

  “And for all our technology and a multibillion-dollar drug industry, leeches are still being used in hospitals today. In fact, in 2004 the FDA approved Hirudo medicinalis as a medical device.”

  I wondered if I’d heard him correctly. “Device?”

  “That’s right. The medicinal leech is only the second-living creature to ever receive that designation.”

  Rudy knew the answer to my next question, so before I could ask it, he said, “Maggots.”

  “Maggots?” I parroted.

  “Sure. Doctors figured out hundreds of years ago that if they applied maggots to an open wound, they’d only eat the dead or decaying tissue—not the viable stuff.”

  “Cool,” I replied, ever the scientist. “So what about leeches?”

  “Most of ours go to hospitals or medical centers where doctors perform reattachment surgeries—ears, scalps, noses, breast reconstructions too. Somebody walks into a hospital carrying their finger in a bag of ice—we get a call.”