Dark Banquet (19 page)

In the years since his death, there have been accusations that Stalin's medical treatment may have been deliberately delayed (although there was apparently a general consensus that thirteen hours wasn't
really
that long of a delay). And, in any event, one could argue that given the state of Soviet medicine in 1953, the wait might not have been such a bad thing.

Finally, James Joyce, the author of
Ulysses,
underwent periodic treatment with leeches, and the results were only somewhat less grim than those experienced by Byron and Stalin. In addition to enduring eleven eye operations during the second half of his life, the Irish writer occasionally had leeches applied around “the outside of his eyes.” It's not clear, however, if this refers to somewhere on his face (surrounding his eyes) or, less likely, one hopes, attached to the
surface
of the eyes themselves. Unfortunately, these treatments were unable to halt the progression of his glaucoma-induced blindness, although Joyce's death in 1941 was unrelated and resulted from a perforated ulcer.

One problem physicians encountered during leech use was that the leeches had an annoying tendency to wander off from where they'd been placed. In cases where leeches were inserted into a body orifice, a lasso of thread was first thrown around the creature to prevent it from taking an unexpected detour. Similarly, when leeches were applied just outside a body opening (as in the treatment of a boxer's cauliflower ear), a wad of cotton might be inserted into the nearby hole to keep the leech from venturing in. Presumably, this became a popular measure in the nineteenth century after a leech was reported to have ascended into one patient's uterus, while in another case, the fast-moving creature disappeared up someone's rectum.
^*79

Rudy Rosenberg explained that in addition to the ease of placing leeches in otherwise hard-to-bleed locations, the resulting bites are painless since one of the substances found in leech saliva is a sensation-numbing anesthetic.

“You might feel a slight pinch,” Rudy Rosenberg told me. “But after that, nothing.”

The ability to deliver bites without upsetting the potential meal is an important adaptation for a lifestyle in which the stealthiest individuals are the ones who survive to reproductive age. As with the bite of the vampire bat, if the leech's prey felt anything more than a minor annoyance, the chances for a successful feeding session would be greatly diminished.

“The medicinal leech has three jaws,” Rudy continued. “They're arranged in a Mercedes-Benz cross and each jaw has around a hundred teeth.
^*80
Muscles that control a hood of skin at the head end of the leech form an airtight seal around the bite site. Then other muscles drive the jaws back and forth through the skin like a saw.”

Leeches that specialize in larger hosts, such as water buffalo or even elephants, have larger jaws with even more denticles. This enables them to cut through the thick, tough hides that they encounter.

As mentioned earlier, the vast majority of leech species, including
Hirudo medicinalis,
have an additional suction cup near the tail.
^†81
This caudal sucker doesn't have denticles associated with it, though, since it functions primarily in locomotion and by providing an additional point of contact for the leech to attach itself to a host's body.

Sucker attachment actually has two components: adhesion via glandular secretions and the generation of negative pressure by a circular disk of muscle that leech expert Roy T. Sawyer described as “a finely tuned suctorial device.” The inner surface of this sucker is lined with glands that secrete a mucuslike polysaccharide that aids in adhesion (in much the same manner that a wad of wet toilet paper clings to a ceiling of a dorm bathroom). In some species that prey on fishes, this adhesive substance is actually a flesh-dissolving enzyme that leaves permanent scarring at the attachment site (which is usually located near the base of a fin).

Rudy explained that none of
Hirudo medicinalis
's adaptations would have elevated it much beyond the status of “rarely encountered but truly disgusting annoyance” were it not for the leech's ability to produce one of the most potent anticoagulants known to man. Identified in the late nineteenth century, the substance (now known as hirudin) was purified in the 1950s and cloned some thirty years later. Like the clot-preventing substances found in vampire bat saliva, hirudin has helped to transform the medicinal leech and some of its relatives into superbly evolved sanguivores. When released into a bite-inflicted wound, hirudin works in combination with a painkilling anesthetic, a blood vessel–widening vasodilator, and another substance (hyaluronidase) that promotes local spreading of the leech's potent salivary stew.

Initially, blood flows from the wound because of negative pressure produced by the anterior suction cup, but before long, suction is enhanced by wavelike peristaltic contractions of the leech's digestive tract. The leech remains attached to its host for up to an hour, sometimes ingesting ten times its body weight in blood (medicinal leeches consume about ten milliliters of blood per meal). Once satiated, the leech (bloated like some blood-filled, organic football) releases its suction grip and falls off. Depending on the species, leeches can survive up to three years between blood meals.

For the host, even after the leech drops off, the effects of the bite are far from over. Bleeding from the wound site continues for up to ten hours, and like the aftermath of a vampire bat attack, this can leave a considerable mess. Even under controlled conditions, patients undergoing leech therapy sometimes require transfusions to replace blood lost
after
the leech finishes feeding.

In addition to an often-significant loss of blood, there can be additional problems for the leech-bitten.
Aeromonas hydrophila
is an endosymbiotic bacterium that lives in the leech's gut. This organism can produce infection at the wound site as well as diarrhea for the human host. Because of this, leech treatment is often accompanied by a regimen of antibiotics.

What's
Aeromonas
doing inside the leech?

Researchers believe that in addition to assisting in digestion,
Aeromonas
produces metabolic by-products that serve as vitamins and essential amino acids for the leech. Like other endosymbionts,
Aeromonas
gets a safe place to live, feed, and reproduce. Similarly, other species of endosymbiotic bacteria inhabit the guts of mosquitoes and vampire bats.

Often, leeches carry even nastier pathogens in their saliva—including blood-borne parasites known as trypanosomes. These protists (notable for their prominent, whiplike flagella) are responsible for several serious diseases in their human and nonhuman hosts. Thankfully, leech-to-human transmission is rarely if ever reported—probably owing to the fact that leeches do not carry the infective stages of these flagellates—which are much more likely to be found in creatures like assassin bugs (a family of insects that have evolved a long and complex relationship with trypanosomes).

“Only
Hirudo medicinalis
has the right combination of traits,” Rudy said, with a measure of pride. “Size, bite technique, and just the right amount of hirudin.”

“How do you get them to bite where you want them to?” I asked.

“In the old days, they used a quill or some other hollow tube. They'd place the leech into the tube then hold it against the spot where they wanted it to bite.”

I also learned that barber-surgeons or other “leechers” would place several
Hirudo
into a teacup, invert the cup, and hold it in place on their patient until the leeches got the message and latched on.

“In modern times, though, they'll just cut a small hole in a sterile gauze pad, place the hole over the designated spot, then stick the leech's head near the hole. The gauze keeps the leech from wandering off, but you've
still
got to keep an eye on them.”

“Do they ever turn down a meal?” I asked.

“Oh, they can be
very
picky,” Rudy said with a laugh. “Leeches hate perfumed soaps or smelly hair sprays. Often, they won't attach if the person is a heavy smoker or if they've eaten garlic recently.”

I must have looked confused.

“The patient, that is.”

“Got it,” I said. “So how do you deal with a leech who plays ‘hard to bite'?”

“Most of the time if you clean and shave the potential attachment site, then sprinkle on a couple of drops of blood, sugared water, or even milk—you can whet their appetite.”

“And what if that doesn't work?”

“You can try abrading the skin a bit. Other times you can get leeches in the mood by immersing them briefly in diluted wine or warm, dark beer. And if they
still
won't bite, we just tell the physician to grab another leech.”
^*82

“What happens to the leech
after
a treatment?”

Rudy frowned at this one. “Well, unfortunately, the treatment turns out to be their last meal,” he replied. “Scientists have figured out that some human blood cells remain alive within a medicinal leech for up to six months.” Evidently, they're still trying to figure out how this works but it appears to have something to do with the
Aeromonas
bacteria releasing chemicals that kill off other bacteria that might be present. Bacteria that would have presumably contributed to the destruction of the blood had they been alive and active.

“Anyway, blood-borne diseases can be transmitted if leeches get reapplied to someone else—so the bottom line is that once they feed, leeches are treated as medical waste.”

“And how do you dispose of them?”

“Submerse them in alcohol, generally,” Rudy said, then he looked at me over the top of his glasses again. “But you
never
want to flush them down the toilet.”

I immediately took the bait. “Why's that?”

“Well, one day I got a call from a hospital. For some reason they'd decided to get rid of their leeches—so they flushed them.”

“And?”

I noticed that the leech maven could barely contain his glee.

“Well, apparently the leeches loved the idea. They're escape artists to begin with—and pretty soon they started showing up in toilets all over the hospital. The hospital people were kind of frantic by the time they called me.”

“What did you tell them?” I was already envisioning some truly unique target practice opportunities.

Rudy threw up his hands. “I told them to get a net.”

In the late nineteenth century, medical advances began to overshadow ancient techniques like bloodletting and leeching. Physicians shifted their focus from humeral imbalances to bacteria as the causative agents for diseases and infections. A few daring researchers even claimed that bleeding a patient might do them more harm than good. Not surprisingly, the medical community showed some initial resistance to revamping, so to speak, what had been a longstanding therapeutic procedure. Some of these physicians apparently had more of a problem abandoning the idea of bleeding patients than others, going so far as to claim that industrialization or even changes in the earth's magnetic field had led to the recent ineffectiveness of bloodletting.