Speaker 1: As a general surgery resident, you tend to expect the
Speaker 1: unexpected and very little surprises you. But one morning during
Speaker 1: my plastic surgery rotation during my intern year stands out
Speaker 1: as a once in a lifetime experience. A patient to
Speaker 1: come in overnight who, while working with machinery, completely severed
Speaker 1: their thumb from their hand. One of the microsurgeons was
Speaker 1: able to painstakingly reattach it, giving the patient a small
Speaker 1: but very real chance to keep their thumb. Excited to
Speaker 1: meet the patient and see the aforementioned thumb, I waited
Speaker 1: outside the room for the plastic surgery residents to join
Speaker 1: me for rounds. Once they did, I noticed a small
Speaker 1: styrofoam cup in the chief resident's hand, which I thought
Speaker 1: was interesting considering we typically don't get coffee until after rounds.
Speaker 1: He then asked me and the other residents if we
Speaker 1: were ready for this, as he showed us what was
Speaker 1: in the cup. Starkly contrasting the inside of the white
Speaker 1: cup were four dark, undulating masses, and then it all
Speaker 1: kind of clicked at once for me reattached thumb.
Speaker 2: We need to rest or blood flow.
Speaker 1: Of course, these are leeches. I feel like a lot
Speaker 1: of my medical training was a process of either dispelling
Speaker 1: or reaffirming random bits of information I collected from unknown
Speaker 1: sources throughout my life, and leeches ended up being the latter.
Speaker 1: The leeches had been literally bred for this in a
Speaker 1: sterile environment, to be used once and only once placed
Speaker 1: on a future line where the reattached flesh met the hand,
Speaker 1: the leeches would feed, promoting blood flow by keeping the
Speaker 1: blood from clotting. Then when full, they would fall off,
Speaker 1: at which point they'd be collected and a new leach
Speaker 1: would be placed, rinse, in repeat. I was told the
Speaker 1: hospital had a policy where the first leech had to
Speaker 1: be placed by a physician, and once it took to
Speaker 1: the patient, the following leaches could be placed by nurses.
Speaker 1: So we were there that morning to place the first one.
Speaker 1: The patient only spoke Spanish, so we had an interpreter
Speaker 1: via phone service help with informed consent. This is when
Speaker 1: things truly got weird. After the chief resident explained the plan,
Speaker 1: the patient became came very uneasy and upset. After a
Speaker 1: bit of confusion, we decided to wait for an in
Speaker 1: person interpreter to try again. It turns out, during our
Speaker 1: literal game of telephone, the word leech somehow transformed into
Speaker 1: venomous snake. Despite taking Spanish in high school, I am
Speaker 1: not fluent and I have no idea how this happened,
Speaker 1: so already off to a poor start, we spent some
Speaker 1: time basically finding different ways to say no, it's not
Speaker 1: venomous snakes, it's just leeches, which I feel is like
Speaker 1: saying no, no, don't worry, I'm not going to steal
Speaker 1: your car, just your engine and your tires. It's definitely better,
Speaker 1: but by how much? The misinterpretation was finally sorted out
Speaker 1: and shout out to medical interpreters and all interpreters everywhere,
Speaker 1: we would be totally lost without you, and the patient
Speaker 1: finally consented to leech therapy. The resident then tried to
Speaker 1: place the first leach onto the area, but the leech
Speaker 1: had other plans and wasn't really into latching on at
Speaker 1: the time. During what seemed like hours but was probably
Speaker 1: just a couple of minutes, the resident tried again and
Speaker 1: again to get the leech to literally bite, to no avail.
Speaker 1: With everyone in the room singularly focused on the reluctant creature,
Speaker 1: no one noticed that the cup with the other leeches
Speaker 1: in his other hand were as precariously tilted over the patient,
Speaker 1: and one adventurous leech had made its way to the
Speaker 1: lip of the cup and onto the gloved finger of
Speaker 1: the resident. Another resident in the room finally noticed and
Speaker 1: brought it to his attention, but instead of very calmly
Speaker 1: stopping what he was doing and making very simple movements
Speaker 1: to remedy the situation, his fight or flight response kicked in.
Speaker 1: He let out what I can only describe as a
Speaker 1: genuine shriek and inadvertently dumped the cup and its contents
Speaker 1: onto the patient's lap. Needless to say, the patient was
Speaker 1: about as freaked out as humanly possible at this point,
Speaker 1: but we did eventually get the leeches to latch. Unfortunately,
Speaker 1: and independent of these hectic events, the tissue was too
Speaker 1: far gone, did not regain enough blood flow, and the
Speaker 1: thumb could not be saved. I wish more could have
Speaker 1: been done for the patient, especially under those circumstances, and
Speaker 1: I really hope they're doing well wherever they are. But
Speaker 1: I truly appreciate the experience to learn how leeches can
Speaker 1: potentially help us even in modern times.
Speaker 2: I just the the visual of like the leech slowly
Speaker 2: making its way and banking up the cup, the scream,
Speaker 2: and the Yeah streak. Specifically, that amazing first hand account
Speaker 2: comes from friend of the pod, doctor Robert Rowe, who
Speaker 2: is a preventative medicine physician who serves as adjunct faculty
Speaker 2: with both the University of North Carolina Preventative Medicine Residency
Speaker 2: Program and the Gilling School of Global Public Health. He
Speaker 2: is also the creator and host of tar Heel Wellness
Speaker 2: spelled h e a L, which is a podcast dedicated
Speaker 2: to the health and well being of medical residence. It
Speaker 2: touches on physical and mental challenges that many other people
Speaker 2: face as well, and it's available wherever you get your podcasts.
Speaker 2: You should definitely check it out. Yeah, we're going to
Speaker 2: be on it at some upcoming time, I think, which
Speaker 2: will be really I'm really excited about it.
Speaker 3: Yeah, it's going to be so fun.
Speaker 2: But yeah, I what an amazing story. Thank you so much.
Speaker 3: Thanks doctor ro much for not only telling us that
Speaker 3: story and then being willing to tell it again so
Speaker 3: that we could share it on the podcast, Because the
Speaker 3: first time we heard it we were like, I'm sorry,
Speaker 3: that's too good of a story.
Speaker 2: You please please share.
Speaker 3: Yeah.
Speaker 2: Hi, I'm Aaron Welsh and I'm erin allman Updike and
Speaker 2: this is this podcast will kill you.
Speaker 3: Today's as promised, an incredible companion episode to last week,
Speaker 3: all about leeches.
Speaker 2: Just when you thought it couldn't get simultaneously grosser and cooler,
Speaker 2: it's about to.
Speaker 3: Before researching for these two episodes, was there one or
Speaker 3: the other of these that like grossed you out more,
Speaker 3: just like as a general thing, because I feel I
Speaker 3: have an opinion about that.
Speaker 2: Oh yeah, for me, it's maggots interesting.
Speaker 3: Yeah, Leeches for some reason absolutely creep me out. I
Speaker 3: don't think I've ever seen one in real life, but
Speaker 3: they just I don't Something about the idea of them
Speaker 3: freaks me out.
Speaker 2: That is very interesting because I love them both so
Speaker 2: much now like now, but I think I would still
Speaker 2: have a difficult time, like getting over the visual of maggots.
Speaker 2: Leeches don't bother me and maybe interesting, I don't know why. Also,
Speaker 2: I need to apologize and advance to you because I
Speaker 2: have some gnarly leech facts that I with and share
Speaker 2: with you. I can't wait may reinforce some of these
Speaker 2: leech wariness that you have.
Speaker 3: It's okay, I'm mostly a saltwater girl. So I think
Speaker 3: I'm gonna be fine.
Speaker 2: You're not. There are saltwater leeches. Oh no, this is
Speaker 2: gonna be up there.
Speaker 3: Okay, because you know the other thing that actually terrifies
Speaker 3: me more than anything in the ocean is snakes, like
Speaker 3: sea snakes.
Speaker 2: Oh yeah, so now.
Speaker 3: I get to also be afraid of sea leeches apparently.
Speaker 2: Are you afraid of terrestrial snakes?
Speaker 3: No, not at all, love.
Speaker 2: Them, okay, just sea snakes.
Speaker 3: Sea snakes. Have you seen them? Swims?
Speaker 2: Yeah? I have. And I also feel like there was
Speaker 2: a formative documentary that I watched, probably on like Animal
Speaker 2: Planet growing up, where it was like sea snakes are
Speaker 2: the deadliest of all animals.
Speaker 3: And that is still what's burned in my memory is truth.
Speaker 3: So but today we're not talking about snakes.
Speaker 2: No, We're here to talk about leeches. Yes, And because
Speaker 2: this is a companion piece to last week's episode on Maggots,
Speaker 2: which if you haven't listened to yet, oh my gosh,
Speaker 2: really don't be don't be too discouraged or grossed out.
Speaker 2: Well that's hert kind of a hard thing to ask,
Speaker 2: but I promise you there are some really cool nuggets
Speaker 2: of information in the Maggots episode, but because this is
Speaker 2: a companion piece, we are doing one quarantini for both
Speaker 2: episodes because it is a tale of two worms. Get it, huh?
Speaker 2: And in a tale of two worms. In case you
Speaker 2: missed out on the Maggots episode, which again go listen
Speaker 2: to it. You can find ingredients such as vodka, lime juice,
Speaker 2: cranberry juice, pineapple juice, orange juice, ginger ale basically fruit punch,
Speaker 2: fruit punch.
Speaker 3: It's fantastic. The full recipe, it's already up on our website,
Speaker 3: this podcast, Wikilli dot com, and all of our socials,
Speaker 3: so hopefully you've got one in hand for this episode.
Speaker 2: Yeah, socials, follow up socials on them. We've got some
Speaker 2: good content, really, we really do. It's pretty It's pretty cool.
Speaker 2: That's all I've got to say about that. But we
Speaker 2: also have a website where you can find all sorts
Speaker 2: of cool things, including but not limited to, transcripts, the
Speaker 2: links to bookshop dot org and our Goodreads list, sources
Speaker 2: for all of our episodes, links to merch links to
Speaker 2: our Patreon, links to a first hand account form. You know,
Speaker 2: there's more stuff. There's so much our website.
Speaker 3: Check it out. This podcast will kill You dot com yeah,
Speaker 3: well with that, should we get into leeches one, we
Speaker 3: should right after this break. So leeches are actually worms, surprise, surprise. Specifically,
Speaker 3: leeches are a type of analid worm, which are the
Speaker 3: segmented worms like your earthworms worms that people know about.
Speaker 3: And there are a lot of different species of leech,
Speaker 3: the vast majority of which are either permanent or temporary
Speaker 3: external parasites, so they suck on blood and that is
Speaker 3: what they live on. All of the ones that are
Speaker 3: used in medicine fall under the family Hyrudinidae, which suck
Speaker 3: our blood but also like amphibian's blood. They're pretty like
Speaker 3: they'll eat a lot of different things, and a couple
Speaker 3: of the most commonly used species in medicine are Hiroudo
Speaker 3: medicinelyis what a what a logical name, and several other
Speaker 3: species of hiroudo as well, and then at least a
Speaker 3: few other species as well in nature, like when not
Speaker 3: grown in a lab because spoilers. Just like with maggots,
Speaker 3: the ones that we use in medicine are all grown
Speaker 3: in a lab and they're all sterilized before they're used,
Speaker 3: but in nature they tend to live in like warm,
Speaker 3: shallow still pools the types of habitats that amphibians prefer,
Speaker 3: because amphibians are apparently quite a good food source for them,
Speaker 3: and leeches have classically, if you think of a leech,
Speaker 3: if you've ever seen what's that movie?
Speaker 2: Stand by me, yes, I was thinking the same thing.
Speaker 3: That's what I think of when I think of leeches
Speaker 3: every single time. And he goes bung. Okay. So leeches
Speaker 3: have two suckers, right, They've got one on their front
Speaker 3: end and one on their back end. And the front
Speaker 3: end is the business end. That's the end that we'll
Speaker 3: focus on. The posterior sucker they use just for clinging
Speaker 3: and for moving.
Speaker 2: I do, I do.
Speaker 3: And while maggots that we talked about have no biting
Speaker 3: mouth of which to speak, leeches, on the other hand,
Speaker 3: are equipped with not one, not two, but three jaws
Speaker 3: that are arranged like a pyramid. Each one of these
Speaker 3: jaws has sixty to one hundred teeth on them. Eron,
Speaker 3: I know it's terrifying. If you look at like close
Speaker 3: up images of leech jaws, it is they look like
Speaker 3: an alien. They look like they're terrifying, but that's why
Speaker 3: they leave. If you've ever seen a leech bite Mark,
Speaker 3: it's like a little y shaped bite. It's because they've
Speaker 3: got these three jaws that come together and take the
Speaker 3: whole chunk out of you. That's so cool, I know,
Speaker 3: and also cool are leeches themselves leeches. They're very fascinating
Speaker 3: and the most useful part of leeches medicinally is by
Speaker 3: far their saliva. Leech saliva contains over one hundred bioactive substances.
Speaker 3: I'm sorry. So after they bite us with their like
Speaker 3: hundreds of teeth, leeches inject their saliva into us, and
Speaker 3: then they suck up our blood. That's what they're feeding on.
Speaker 3: When they do this, they're sucking up several times their
Speaker 3: body weight in blood so that they can go several months,
Speaker 3: in fact, up to a year between blood meals.
Speaker 2: Erin, erin, I have read. I'm gonna pull up my
Speaker 2: notes real quick because I wrote this in a random
Speaker 2: spot and I have just written leeches live for eighteen
Speaker 2: to twenty seven years in the wild question. I'd love to.
Speaker 3: Say you wrote that, because I have How long does
Speaker 3: a leech live for? I still don't know. But they
Speaker 3: can fast for a year and a half. What the heck?
Speaker 2: That is amazing.
Speaker 3: Eighteen to twenty seven years.
Speaker 2: Yeah, and now I'm about to fact check myself because
Speaker 2: I want to make sure that that has a citation involved. Amazing,
Speaker 2: all right, So we did just do some fact checking.
Speaker 2: We fact checked because we couldn't resist. And years is
Speaker 2: definitely on a scale of years. Some sources say up
Speaker 2: to twenty years. I did find a couple sources that
Speaker 2: said that quoted the eighteen to twenty seven and a
Speaker 2: lot of them also say like two to eight, So
Speaker 2: it seems like there might be a range. But it
Speaker 2: seems like the maximum lifespan in a suitable environment could
Speaker 2: be upwards of twenty years, which is I mean, I
Speaker 2: never would have expected more than one year exactly.
Speaker 3: That's like anything beyond I'm sorry, it's a warm it's
Speaker 3: a worm. It's amazing.
Speaker 2: What's the longest lived worm? Do you think someone let
Speaker 2: us know, we're too.
Speaker 3: Many rabbit holes, too many, too many get back to leeches.
Speaker 3: They're sucking all this blood, a whole bunch so that
Speaker 3: they can live their years in between blood meals. So
Speaker 3: for this blood to not just coagulate on removal from
Speaker 3: the body, which is what blood wants to do. That's
Speaker 3: what it does when it removes from the body. Leeches
Speaker 3: have a whole bunch of compounds in their saliva that
Speaker 3: function as anticoagulants. The first, most important and most well
Speaker 3: known and well studied is called herod in. It's like
Speaker 3: named after the leeches, and this is pretty cool. It
Speaker 3: inhibits thrombin, which, if you want to throw all the
Speaker 3: way back to our hemophilia episode, we talked a lot
Speaker 3: in that episode about the cascade of reactions that happens
Speaker 3: in order for our blood to clot, one compound has
Speaker 3: to be activated, which activates another, and on and on
Speaker 3: and on. Thrombin is one of the final enzymes in
Speaker 3: this cascade, so that is what herod in is blocking.
Speaker 3: It's kind of like the bottom or top, depending on
Speaker 3: which way you want to look at it, of this cascade,
Speaker 3: and it's one of the major regulatory steps in coagulation,
Speaker 3: so it's a really effective way to block coagulation. Herod
Speaker 3: In was synthesized via recombinant DNA and it's used medicinally today.
Speaker 3: We use it all the time in medicine, especially if
Speaker 3: people can't use heparin, either because they've had a reaction
Speaker 3: to it or because they're allergic or for whatever reason.
Speaker 3: But that's not all I said. They have a hundred
Speaker 3: bioactive substances. They have a bunch of other substances that
Speaker 3: block other parts of the coagulation cascade, like factor ten a,
Speaker 3: et cetera. Blah blah blah. They also have a bunch
Speaker 3: of compounds that block platelets from aggregating allah aspirin, which
Speaker 3: means that they're stopping that first part of the coagulation
Speaker 3: because platelets are one of the first things. But what
Speaker 3: it also means in us is that our wounds from
Speaker 3: a leech are going to ooze for a long time
Speaker 3: because platelets are one of the first things that we
Speaker 3: would use to stop, and they injected that saliva into us, right.
Speaker 3: But that's not even all. They also have a whole
Speaker 3: bunch of other enzymes. Some of them serve to increase
Speaker 3: the permeability of our connective tissue, which for the leech
Speaker 3: allows for their secretions to penetrate more deeply into our
Speaker 3: tissues so that they work more Medicinally. What this can
Speaker 3: do is promote resorption of fluid and blood because it's
Speaker 3: increasing the permeability of the connective spaces. They also have
Speaker 3: enzymes that help to dissolve any blood clots that have
Speaker 3: already formed, and a lot of the things that they release,
Speaker 3: they're soesting much helps with vasodilation and reducing scar tissue formation.
Speaker 3: Like the list goes on, and we still don't know
Speaker 3: the mechanisms of every one of these compounds. There's also
Speaker 3: analgesic properties that we definitely don't understand, which makes the
Speaker 3: biting of those hundreds of leech teeth, or at least
Speaker 3: the sucking process a little bit less painful, perhaps, so
Speaker 3: you can imagine that with so many amazing things present
Speaker 3: in their saliva, leeches are used for a pretty wide
Speaker 3: variety of things, or I should say they've been studied
Speaker 3: for a pretty wide variety of things, because today they're
Speaker 3: most often used for post surgical care, especially in complicated
Speaker 3: procedures like what we heard in our first hand account
Speaker 3: with the reattachment of a finger, like skin flaps, reconstructions,
Speaker 3: places where you really don't want a lot of venous
Speaker 3: swelling or a lot of edema, like overall swelling in
Speaker 3: the tissue, because leeches are really good at reducing that
Speaker 3: kind of swelling, both by physically removing that venous blood
Speaker 3: but also by just reducing inflammation overall, and they leave
Speaker 3: these little wounds open to ooze for a few days,
Speaker 3: which can also be beneficial. But leeches have been evaluated
Speaker 3: for a lot of other things that I found fascinating
Speaker 3: and would never have expected people to use leeches for.
Speaker 3: The one that has the most evidence thus far is
Speaker 3: in the treatment of osteoarthritis. Of all things. Huh, yeah,
Speaker 3: that's my face too. So leeches have been studied for
Speaker 3: treatment of a lot of different kinds of arthritis, the
Speaker 3: idea being very similar that it's reducing inflammation around the joints,
Speaker 3: which is the cause of a lot of pain in arthritis,
Speaker 3: and a few larger meta analyzes seem to show some
Speaker 3: benefit in osteoorithritis at least for pain reduction and an
Speaker 3: increase in mobility. For other types of things like rheumatorid
Speaker 3: arthritis or even ankylosinkspondylitis, there's been at least like case studies,
Speaker 3: not necessarily large studies, but people have also tried to
Speaker 3: use leeches for things like migraines, TMJ, high blood pressure,
Speaker 3: heart disease, even some neurologic disorders, and at least the
Speaker 3: published studies on these seem to show benefit, but it's
Speaker 3: a really minimal amount of data. For any of these
Speaker 3: other conditions. You're not going to find people who are
Speaker 3: going to give you leeches for your blood pressure, like
Speaker 3: that's not a thing. But for reconstructive surgery, it absolutely
Speaker 3: is a thing. Yeah, and some people have used leeches
Speaker 3: for the treatment of chronic wounds, so you could use
Speaker 3: leeches and maggots together.
Speaker 2: In in combination. All that's amazing. I know that. That
Speaker 2: is leeches, you know, I love them.
Speaker 3: Their saliva is incredible.
Speaker 2: It's magic. Yeah, it's more powerful than magic. It's nature.
Speaker 3: So Aaron, tell me, yeah, tell me about the history
Speaker 3: of these little suckers, get it nice?
Speaker 1: Uh?
Speaker 2: Yeah, I can absolutely do that. Let's take a quick
Speaker 2: break and then I'll tell you as much as I
Speaker 2: can about leeches. All right, Before I get into the long,
Speaker 2: long history of leeches used in medicine, I wanted to
Speaker 2: first take a bit of time to just get to
Speaker 2: know this group of animals a little bit more broadly. Okay,
Speaker 2: so much fun. And estimated seven hundred species of leeches
Speaker 2: have been described, did you wow? Seven hundred? Yeah, and
Speaker 2: they can be found on all continents and seas except Antarctica.
Speaker 2: They live in caves, in saltwater, in fresh water, in
Speaker 2: hot water, in freezing water, in shallow water, in deep water.
Speaker 2: The record is over seventy eight hundred meters yep. I
Speaker 2: have to.
Speaker 3: Say these last two episodes are making me feel like
Speaker 3: I did all of my invertebrate zoology classes poorly by
Speaker 3: not remember any of this.
Speaker 2: Oh, if I once knew this, I have long forgotten it.
Speaker 3: Maybe I just never learned it. But like, okay, you.
Speaker 2: Keep going, please, okay, okay. They leeches also live in
Speaker 2: arsenic laced water, in super alkaline water, not in water
Speaker 2: at all, but on moist land. It's pretty rad Okay,
Speaker 2: a land leach, a land leech. And okay, if we
Speaker 2: say picture a leech, most of us are going to
Speaker 2: picture those leeches from stand by Me that we talked about,
Speaker 2: or something very similar. But did you know that only
Speaker 2: about half of leeches feed on blood?
Speaker 3: No? I thought most of them dead half half half?
Speaker 3: But are most of them still parasitic?
Speaker 1: Well?
Speaker 2: The other ones feed on things like earthworms, gastropods, crustaceans,
Speaker 2: and insect larvae like.
Speaker 3: As parasites more as like just cavor predators.
Speaker 2: Yeah. Yeah, one of the biggest leeches, reaching lengths of
Speaker 2: up to three hundred millimeters, which is nearly one foot
Speaker 2: eleven point eight inches. Uh, preys on worms.
Speaker 3: It eats other worms.
Speaker 2: It eats other worms. But the biggest leech, I'm going
Speaker 2: to try to pronounce this Hementaria GILLANII, gets up to
Speaker 2: four hundred and fifty millimeters long seventeen point seven inches erin.
Speaker 3: That is very large for a worm.
Speaker 2: Nearly four inches in width. And this guy does feed
Speaker 2: on blood. Who's blood, lots of different types of blood.
Speaker 2: So humans have been observed rabbits, cows, birds, Okay, but
Speaker 2: how do leeches find their prey, you might ask? They
Speaker 2: use many different sensory clues. As a matter of fact,
Speaker 2: So terrestrial leeches sense things like ground vibrations, whether the
Speaker 2: leaves and dirt or whatever they're laying in gets moved
Speaker 2: around or disturbed, shadows, air currents, and maybe, although it's
Speaker 2: been debated co two from the breath of their intended prey.
Speaker 2: Aquatic leeches use things like water currents or temperature or
Speaker 2: disturbance to detect prey. It's amazing and I have several more.
Speaker 2: If you don't mind me sharing a few more cool
Speaker 2: bits of leech trivia. Okay please. Leeches can live in
Speaker 2: extreme temperatures, not like the same leach or the same
Speaker 2: leech species, but for example, the freshwater leach. This is
Speaker 2: the names of these leeches. I'm telling you what challenging.
Speaker 2: Ozobrancis jancianus quote survived at negative one hundred and ninety
Speaker 2: six degrees celsius for twenty four hours and up to
Speaker 2: thirty two months at minus nine degree celsius.
Speaker 3: Wow.
Speaker 2: And on the other side of the spectrum, the marine leech. Oh,
Speaker 2: this is the hardest one of all. I think it's
Speaker 2: the last one. No, it's not. I see another one
Speaker 2: down there. Zeylanicobdella arugamensis has been found to survive at
Speaker 2: temperatures from twenty degrees celsius to forty degrees celsius, which
Speaker 2: is sixty eight to one hundred and four degrees fahrenheit.
Speaker 2: Blood feeding leeches can also get creative with where they feed,
Speaker 2: such as up the nostrils or behind the eyeballs of
Speaker 2: humans and livestock.
Speaker 3: Did you just say behind the eyeballs?
Speaker 2: Yeah? Apparently no? No, eh, at least I think it
Speaker 2: the eyelid. Yeah, okay, uh huh h. But I think
Speaker 2: the one in terms of unique feeding location choices, the
Speaker 2: one that takes the cake is Placo Deloit's Jaeger SKIOLDI,
Speaker 2: which I know that I totally did not pronounce correctly,
Speaker 2: but like, I'm sorry. This leech actively swims, it can
Speaker 2: actively swim, and it does this swims to its hippopotamus host,
Speaker 2: where it will invade the hippo's rectum and commence blood
Speaker 2: feeding only.
Speaker 3: In the rectum, poor hippo.
Speaker 2: Yeah, but now that I've completely spent all of the
Speaker 2: goodwill that we had previously built up for leeches, let
Speaker 2: me attempt to like bring you all back on board.
Speaker 3: Get you to like a leech again.
Speaker 2: Yeah. I know that it's like we're it's an uphill battle,
Speaker 2: but I think that we can do it because I
Speaker 2: want to tell you about leech reproduction, especially parental care.
Speaker 2: What parental care exactly? See goodwill returned. So, First of all,
Speaker 2: leeches have both male and female reproductive organs, which means
Speaker 2: that while they don't always or even often self fertilized,
Speaker 2: they absolutely can and that's this does happen. And second,
Speaker 2: leeches produce these things called cocoons, which come in lots
Speaker 2: of different textures. But that's where leech eggs develop inside
Speaker 2: this cocoon with like a nutrient soup that lasts until
Speaker 2: the eggs turn into juveniles and then can strike out
Speaker 2: on their own. Huh, it's so cute. But some leeches
Speaker 2: go beyond the cocoon. Leeches in the gloss of Phonia
Speaker 2: day care for their eggs both before and after they hatch,
Speaker 2: either in a little cocoon nest or on their body
Speaker 2: or in a little pouch like a kangaroo.
Speaker 3: Little kangaroo leech pouch.
Speaker 2: Uh huh. Once the eggs have hatched, some leeches will
Speaker 2: bring them food like snails or mosquito larvae or quote
Speaker 2: by transferring nutrients across the body wall to the developing
Speaker 2: young in a manner reminiscent of a placenta. Oh, isn't
Speaker 2: that amazing? But there's more, because researchers have observed that
Speaker 2: in times where food is scarce, some leech parents will
Speaker 2: starve themselves so that they're young can feed. Wow. Some
Speaker 2: species live in groups with adults and young together, sharing
Speaker 2: food and even caring for young that aren't their own.
Speaker 3: I don't think I ever thought about leeches, even worm
Speaker 3: like behavior.
Speaker 2: This much I know, and it is incredible. I am
Speaker 2: in awe interesting. Yeah. Yeah, the diversity found among leeches
Speaker 2: is incredible, and there are so many species that haven't
Speaker 2: yet been studied, or haven't been studied very much, or
Speaker 2: have yet to be discovered on their own. Leeches are amazing.
Speaker 2: But if you want a human centric perspective to convince
Speaker 2: you that leeches are worthy of study and conservation, consider
Speaker 2: the powerful anticoagulant herodin found in the medicinal leeches saliva
Speaker 2: and how it's now used in medicine. That's just one
Speaker 2: of the amazing compounds found in that leech species saliva,
Speaker 2: and there are many more leeches with many other cool
Speaker 2: salivary compounds like hemantin and anticoagulant found in the giant
Speaker 2: Amazon leech that targets fibrinogen formed blood clots, theremine which
Speaker 2: inhibits thrombin like herodin, but it seems to be different.
Speaker 2: And then there's the bacterial endosymbions of leeches. Leeches that
Speaker 2: feed on blood have bacteria that will help break down
Speaker 2: blood and provide essential vitamins. So if you want this
Speaker 2: human centric reason for why preserving biodiversity is important. Consider
Speaker 2: the leech, like not just the medicinal leech, but all leeches.
Speaker 2: But now turning towards the medicinal leech, which actually turns
Speaker 2: out might be made up of multiple species or like
Speaker 2: morphs or something. Yeah, let's get into how humans have
Speaker 2: used these leeches throughout history. Okay, like maggots, The use
Speaker 2: of leeches in medicine goes way way back. I'm talking
Speaker 2: fifteen hundred BCE ancient Egypt, murals in a tomb depicting
Speaker 2: the bloodsucking powers of a leech. Wayback.
Speaker 3: Wow.
Speaker 2: Yeah, ancient Mesopotamia, ancient India, ancient Greece, and Rome, likely
Speaker 2: in ancient Central and South America, ancient China. There's evidence
Speaker 2: that leeches have been used medicinally all around the world
Speaker 2: for thousands of years. And this isn't a case of
Speaker 2: like an occasional mention or reaching for the leech only
Speaker 2: when everything else failed. Leeches were a very regular treatment
Speaker 2: in many places around the world for millennia, so much
Speaker 2: so that, Okay, the etymology does get a little tricky
Speaker 2: because when we were setting up for this episode, I
Speaker 2: was like, let me just refresh my etymology notes and
Speaker 2: make sure that I am right in this, And it
Speaker 2: turns out I wasn't. It turns out the truth is
Speaker 2: a little more complicated. So, okay, my initial reading and
Speaker 2: a lot of papers will say that the word leech
Speaker 2: may have come from the Old English word lay say,
Speaker 2: meaning physician. Okay, turns out that there were two. From
Speaker 2: what I can tell, there's one paper that talks about
Speaker 2: there being two independent origins and meanings for that word
Speaker 2: lace or lay say, meaning one meaning physician and one
Speaker 2: for leech. And then the two kind of merged because
Speaker 2: for a really long time one of the synonyms for
Speaker 2: a physician was leech. Interesting because doctors used leeches so frequently,
Speaker 2: So it.
Speaker 3: Wasn't that like the name leech came from doctors. It
Speaker 3: was like they called them the same thing because they
Speaker 3: used them so much.
Speaker 2: Maybe yes, I think that definitely their meanings merged to
Speaker 2: a certain degree or something to that effect. I'll link
Speaker 2: to the paper that goes more into the etymology. But
Speaker 2: like it, it's like we don't know which came first,
Speaker 2: and whether leech was for the worm, and then physician
Speaker 2: became known as a leech or leech became known from physician,
Speaker 2: and it sounded maybe like the worm something like that. Okay, Anyway,
Speaker 2: it makes sense that the two would be synonymous over
Speaker 2: much of the ancient world up until the eighteen hundreds
Speaker 2: or so because of what we know about medicine during
Speaker 2: this long period of time, i e. That it was
Speaker 2: obsessed with blood and blood letting. So these these leeches
Speaker 2: took up residence as like a permanent tool, almost in
Speaker 2: the phlebotomous toolkit. So I've talked about the humoral theory
Speaker 2: of disease like one million times exactly on this podcast exactly.
Speaker 2: So here's one million and one just for a refresher. Essentially,
Speaker 2: there were thought to be four humors in the body,
Speaker 2: yellow bile, black bile, phlegm, and blood. Diseases resulted from
Speaker 2: an imbalance in the four humors. So that could mean
Speaker 2: too much blood, in which case you do some blood
Speaker 2: letting until the balance is restored. In the blood letter's toolkit,
Speaker 2: you could find things like lances, little pocket knives called flemes,
Speaker 2: bleeding cups, syringes. Because certain situations required certain solutions, many
Speaker 2: of these tools were just like a brute force attack,
Speaker 2: like we need to get a lot of blood out
Speaker 2: of you, and we need to do it now. Leeches
Speaker 2: came in handy when a gentle touch was warranted, when
Speaker 2: the desired volume of blood removed was on the order
Speaker 2: of millily rather than leaders, or when the area that
Speaker 2: needed bleeding was in a particularly sensitive or hard to
Speaker 2: reach zone. Okay, like in cases of hemorrhoidal congestion, rectal prolapse,
Speaker 2: volvo vaginitis, orchi epididimitis, hydroceal laryngitis, tonsilitis tonsilitis erin, tonsilitis
Speaker 2: what I know, inflammation of the cervix ouch. Yeah, even
Speaker 2: some eye conditions.
Speaker 3: Yees yeah wowow.
Speaker 2: But even though it's like really hard to think about
Speaker 2: and makes me feel squirmy, this would have been less
Speaker 2: painful than the like a blade on a spring like
Speaker 2: some of these blood letters tools definitely, and like you mentioned, Aaron,
Speaker 2: leeches were also used for wound healing. Latifel Baghdati in
Speaker 2: the twelfth century described how leeches were helpful in tissue
Speaker 2: cleansing after surgery, which is amazing.
Speaker 3: I love it.
Speaker 2: And unlike maggots, who, like we talked about, their popularity
Speaker 2: seemed to wax and wane over the centuries, leeches were
Speaker 2: just like on the up until the late nineteenth century
Speaker 2: in the Middle Ages and Renaissance, sometimes referred to as
Speaker 2: the Golden Age, for blood letting and leeching, leeches were
Speaker 2: used by barber surgeons who would have their patients grip
Speaker 2: a rod, which would possibly later inspire the barber pole.
Speaker 2: You know, like the poles that have that. Yep, So
Speaker 2: that might have been a symbolism for like, grip the
Speaker 2: rod because this will cause your veins to swell and
Speaker 2: that'll make it easier for the leeches to latch onto
Speaker 2: to start the bleeding.
Speaker 3: Interesting.
Speaker 2: Yeah, and then just because I want to expand a
Speaker 2: little bit on the classic barber pole, because what else
Speaker 2: am I going to be able to do it on
Speaker 2: the podcast? Okay, you can picture right like it has, yeah,
Speaker 2: the pole, it has the spinning ribbons, it has blue, red,
Speaker 2: and white often.
Speaker 3: Yeah.
Speaker 2: It has been suggested that the red ribbon theyse all carry,
Speaker 2: meaning the red ribbon, originally came from barbers advertising their
Speaker 2: services by wrapping the bloody linen from a former patient
Speaker 2: around the pole, showing hey we do blood letting here.
Speaker 2: The red means hey, I can bleed you. The white
Speaker 2: ribbon was I can pull teeth and set bones, and
Speaker 2: the blue said I can give you a nice trim
Speaker 2: or shave. Those were allegedly it's one idea as to
Speaker 2: the possible origins of those ribbons. Isn't that great?
Speaker 3: What a wild time to live in?
Speaker 2: I know, I know, I know. Wow. And so if
Speaker 2: you're like, okay, I really want to go get my
Speaker 2: hair cut, but you see the barber pole just has
Speaker 2: red and white, like you're you can get bled, but
Speaker 2: you're not going to have a fresh.
Speaker 3: Shit's they're not going to do trim. Okay.
Speaker 2: Yeah. Anyway, as the popularity of leeches grew over the
Speaker 2: Middle Ages and Renaissance, so did its possible applications from
Speaker 2: neurological and psychiatric conditions like epilepsy to STIs, gastritis, diseases
Speaker 2: of the eye. I just keep seeing uterine applications mentioned
Speaker 2: m boiss Pire, that French surgeon from the fifteen hundreds.
Speaker 2: He dedicated an entire chapter to leeches in his massive treatise,
Speaker 2: and things were only going to get leechier. I don't
Speaker 2: know what exactly constitutes like the golden age of something,
Speaker 2: but I find it hard to believe that like that,
Speaker 2: the Middle Ages and Renaissance for the Golden Age, when
Speaker 2: their popularity only continued to grow into the seventeen hundreds
Speaker 2: and eighteen hundreds too, really unbelievable levels. So peak use
Speaker 2: was in the early eighteen hundreds. Okay, In Europe, physicians
Speaker 2: and barbers kept leeches handy in their offices, in leech jars.
Speaker 2: Some of these jars, Aaron, have you seen pictures of them? No,
Speaker 2: they're beautiful. They're like these beautiful ornate jars that have
Speaker 2: like carved little accessories with like gilded whatever, and it
Speaker 2: says leeches across the front of it. I immediately went
Speaker 2: on eBay, like in the middle of researching, and I
Speaker 2: was like, I need to find an antique leech jar.
Speaker 2: I can't find. I can only find a replica. But
Speaker 2: it's going to be now my life's quest to find
Speaker 2: a leach jar.
Speaker 3: We should go back to the Surgical Sciences Museum in Chicago,
Speaker 3: because I bet if they don't have it, they will
Speaker 3: know where you get it.
Speaker 2: I love them. We'll post a picture because we have to.
Speaker 2: But perhaps no one loved leeches more than Francois Joseph
Speaker 2: Victor Bruce, one of Napoleon's physicians, Napoleon himself had leeches
Speaker 2: to treat hemorrhoids. So cool thing.
Speaker 3: I feel like that would be effective.
Speaker 2: I think so too. Yeah, has that is that one
Speaker 2: of the proposed treatments for today?
Speaker 3: Uh No, I mean Verico's veins, yes, but yes, legs.
Speaker 3: I think that we just have other options these days.
Speaker 3: But I didn't see anything about people using leeches like
Speaker 3: instead of surgery for hemorrhoids. So it's a good, good thought,
Speaker 3: all right, somebody propose it, mm hmm. Maybe it's out
Speaker 3: there and I just missed it.
Speaker 2: Anyway. Bruce was such a fan of blood letting and
Speaker 2: especially leeching, that he was nicknamed quote the vampire of medicine.
Speaker 2: He thought that every disease was attributable to inflammation, especially
Speaker 2: of the GI tract. So like, no matter what the
Speaker 2: condition asthma, broken wrist, smallpox, sore throat, pink eye, it
Speaker 2: all came down to gas and to write us, of course,
Speaker 2: all of it. And so in one example I saw,
Speaker 2: he prescribed the patient a starvation diet and all of
Speaker 2: the leeches that could fit on their abdomen because that's
Speaker 2: where he thought that inflammation would come out of their abdomen. Oh, no,
Speaker 2: somebody was described as looking like they were wearing quote
Speaker 2: a black glittering coat of mail end quote change. Oh god,
Speaker 2: totally yep. And his enthusiasm for leeches may have been unmatched,
Speaker 2: but he was not alone in his love for them.
Speaker 2: Between eighteen twenty nine and eighteen thirty six, So over
Speaker 2: those seven years, do you have a rough guess as
Speaker 2: to how many leeches were used yearly in Parisian hospitals? L. Harris, Yeah,
Speaker 2: you don't have to guess if you're like, I don't even.
Speaker 3: Know, I don't know. Hundreds of thousand's.
Speaker 2: Five to six million each year? Off?
Speaker 3: Is that why they're basically extinct in the wild.
Speaker 2: Yes, this is exactly why. This is why this was
Speaker 2: a total of eighty four thousand kilograms of blood drawn annually. Unfathomable,
Speaker 2: it really is.
Speaker 3: Oh wow.
Speaker 2: A millions more of the medicinal leech, the Heruda medicinalis,
Speaker 2: were exported to the US from Europe. At one point
Speaker 2: thirty million leeches per year exported to that reported to
Speaker 2: the US. Yeah, oh my. And so this huge demand
Speaker 2: even at the time, drove leeches close to extinction, and
Speaker 2: rewards were offered for people who could find a way
Speaker 2: to breed them in the US or find alternative species
Speaker 2: that were as effective without causing harm.
Speaker 3: Wow.
Speaker 2: And eventually this demand would die down as the medicinal
Speaker 2: leech faced the same fate in the late eighteen hundreds,
Speaker 2: as did maggot therapy. Medical advancements like germ theory, a
Speaker 2: better understanding of human anatomy and physiology, and the use
Speaker 2: of statistics showing that blood letting overall was useless to
Speaker 2: harmful for most conditions that they had been used for
Speaker 2: all sent these leeches mostly packing with a few physicians
Speaker 2: hanging onto the practice. And also I get that, like
Speaker 2: you have this beautiful leach star and you're like, what
Speaker 2: do you want me to do? Just like not use this?
Speaker 2: Put something else in it?
Speaker 3: No thing, just keep one for just a couple of years,
Speaker 3: And like, can't just use it every year?
Speaker 2: Right, it's got to come back, Right, It's just like
Speaker 2: low wasted Jens Low writers, it's going to come back.
Speaker 3: Those can't come back.
Speaker 2: It's terrible. I'm not happy about it. But anyway, Also,
Speaker 2: like the maggot, the leech would experience a renaissance later
Speaker 2: in the twentieth century barbers, because barber surgeons and physicians had.
Speaker 2: I've noticed the anti coagulant effects of leeches for a
Speaker 2: long time, how like an area where a leech had
Speaker 2: been attached would continue to bleed longer than if the
Speaker 2: wound had been made by something else, like you talked about.
Speaker 2: And in the eighteen eighties, researchers succeeded in extracting the
Speaker 2: substance that led to this anti coagulant effect, which was
Speaker 2: called herodin in nineteen oh four. For decades, challenges with extractions,
Speaker 2: like how it would take an estimated fifty thousand leashes
Speaker 2: a year to get enough herod in for scientific study,
Speaker 2: and that people who were treated with the extract experienced
Speaker 2: shock because it probably wasn't like properly purified in its extraction.
Speaker 2: This limited its use or investigation. But then, like you
Speaker 2: mentioned aaron, in the nineteen eighties, researchers succeeded in engineering
Speaker 2: the substance, and that's allowed people to study this incredibly
Speaker 2: powerful anti coagulant for all kinds of applications. And leeches
Speaker 2: themselves have experienced a bit of renaissance in the field
Speaker 2: of surgery, especially plastic and reconstructive or microsurgeries, beginning in
Speaker 2: the nineteen sixties. In two thousand and four is when
Speaker 2: the FDA certified leeches as a medical device, and it
Speaker 2: seems like people are getting back on board with these
Speaker 2: powerful little parasitic worms. Like I'm fully on board. I
Speaker 2: feel like what it comes down to, not just with leeches,
Speaker 2: but with maggots two in terms of medicine, is that
Speaker 2: we don't always have to reinvent the wheel, and that
Speaker 2: there may exist things that people have used for a
Speaker 2: really long time that could be really powerful or maybe
Speaker 2: they're not powerful, but also maybe we should check it
Speaker 2: out on a case by case basis and see what
Speaker 2: we find, because it could be something like leeches, it
Speaker 2: could be something like maggots. And I think that these
Speaker 2: past couple episodes have just been so thrilling and fun
Speaker 2: and interesting to put together. And I can absolutely say
Speaker 2: that I have so much more appreciation both leeches and maggots,
Speaker 2: and now I can't pick a favorite.
Speaker 3: Yeah, same, Like, I love that they both exist. I
Speaker 3: love that they both were like licensed by the FDA
Speaker 3: for use. I know, fascinating.
Speaker 2: Yeah, well sources, sources, I think, so okay.
Speaker 3: We can all learn more.
Speaker 2: We can. I am going to shout out too so
Speaker 2: if you want to learn some more leech facts and
Speaker 2: that wasn't enough for you, which who doesn't. Honestly, there's
Speaker 2: so much more in this great paper by Phillips at
Speaker 2: All from twenty twenty titled Leeches in the Extreme Morphological,
Speaker 2: Physiological and Behavioral Adaptations to inhospitable habitats.
Speaker 3: Leeches in the Extreme. I love that China, I know.
Speaker 2: And then the second paper that was mostly about the
Speaker 2: history of leeches in medicine was a paper by Montoni
Speaker 2: and Manelli from twenty twenty two titled From Ancient Leech
Speaker 2: to Direct Thrombin Inhibitors and Beyond New from Old fab.
Speaker 3: I had just a few papers and one book that
Speaker 3: I used predominantly one chapter of and this book actually
Speaker 3: had some information about maggot therapy as well. The book
Speaker 3: was titled Biotherapy History, Principles and Practice, and they had
Speaker 3: an entire chapter on hiroudotherapy or the use of leeches,
Speaker 3: and then a chapter on maggot therapy that I used
Speaker 3: a little bit of last episode. And then a few
Speaker 3: other papers on how leeches are used today and on
Speaker 3: all of the incredible compounds that we found in their saliva,
Speaker 3: and the future of all of that, but you can
Speaker 3: find the list of all of the sources from this
Speaker 3: episode and every single one of our episodes on our
Speaker 3: website this podcast will Kill You dot com under the
Speaker 3: episode s tab A.
Speaker 2: Big thank you again to doctor Row for just an
Speaker 2: amazing story.
Speaker 3: Such an incredible story. Thank you so much for sharing
Speaker 3: it with us. Thank you also to Bloodmobile for providing
Speaker 3: the music for this episode in every single one of
Speaker 3: our episodes.
Speaker 2: Thank you to Leana Scolacci and Tom Bryfogel for the
Speaker 2: audio mixing.
Speaker 3: Thank you to Exactly Right Network, and.
Speaker 2: Thank you to you listeners. You know you made it,
Speaker 2: you did. Congratulations. What do you think about leeches and maggots?
Speaker 2: Do you have a favorite do you have a favorite
Speaker 2: fun fact? Do you have a favorite gross fact?
Speaker 3: Do you love them?
Speaker 2: Do you love them as we love them?
Speaker 3: And as always an extra thank you to our patrons.
Speaker 3: Thank you so much for your support. We really appreciate it.
Speaker 2: We do. Until next time, wash your hands.
Speaker 3: You filthy animals. Um