This Podcast Will Kill You - Ep 142 Leeches: It’s more powerful than magic, it’s nature

Episode Date: June 11, 2024

Did our episode on maggots leave you wanting more squirmy wormy yet oh so cool content? You’re in luck. Because this week, we’re following up our maggots episode with a companion piece on leeches. Leeches have been used by healers and physicians for millennia, and they’ve come back into style for treatments today, for very good reason. If you’ve ever wondered what makes leech saliva so magical, why barber poles are striped with red and white ribbons, or how leeches behave as parents, then this is certainly the episode for you. And we are so excited to be joined by friend of the pod Dr. Robert Rowe, who shares a tale of leeches from the front lines of plastic surgery. Dr. Rowe MD, MBA, MPH is a Preventive Medicine Physician who serves as adjunct faculty with both the University of North Carolina Preventive Medicine Residency Program and the Gillings School of Global Public Health. He is also the creator and host of TarHeal Wellness, a podcast dedicated to the health and wellbeing of medical residents, touching on physical and mental challenges many other people face as well. For those who have friends or family who are doctors or training to be, it's a great way to hear about some of the challenges of residency and how they can work through and overcome them. Available wherever you get your podcasts! See omnystudio.com/listener for privacy information.

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Terms and Conditions Apply. Visit blueapron.com slash terms for more information. I'm Clayton Eckerd. In 2022, I was the lead of ABC's The Bachelor. But here's the thing. Bachelor fans hated him. If I could press a button and rewind it all I would. That's when his life took a disturbing turn.

A one-night stand would end in a courtroom. The media is here. this case has gone viral. The dating contract. Agree to date me, but I'm also suing you. This is unlike anything I've ever seen before. I'm Stephanie Young. Listen to Love Trapped on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts.

This is Special Agent Regal, Special Agent Bradley Hall. In 2018, the FBI took down a ring of spies working for China's Ministry of State Security, one of the most mysterious intelligence agencies in the world. The Sixth Bureau podcast is a story of the inner workings of the MSS and how one man's ambition and mistakes opened its fault of secrets. Listen to the Sixth Bureau on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. As a general surgery resident, you tend to expect the unexpected and very little surprises you. But one morning during my plastic surgery rotation, during my intern year, stands out as a once-in-a-lifetime experience.

A patient had come in overnight, who, while working with machines, completely severed their thumb from their hand. One of the microsurgeons was able to painstakingly reattach it, giving the patient a small but very real chance to keep their thumb. Excited to meet the patient and see the aforementioned thumb, I waited outside the room for the plastic surgery residents to join me for rounds. Once they did, I noticed a small styrofoam cup in the chief resident's hand, which I thought was interesting considering we typically don't get coffee until after rounds.

He then asked me and the other residents if we were ready for this, as he showed us what was in the cup. Starkly contrasting the inside of the white cup were four dark, undulating masses. And that it all kind of clicked at once for me. Reattached thumb, we need to restore blood flow, of course, these are leeches. I feel like a lot of my medical training was a process of either dispelling or reaffirming random bits of information I collected from unknown sources throughout my life. and leeches ended up being the latter. The leeches had been literally bred for this in a sterile environment to be used once and only once,

placed on a suture line where the reattached flesh met the hand. The leeches would feed, promoting blood flow by keeping the blood from clotting. Then when full, they would fall off, at which point they'd be collected, and a new leech would be placed. Rinse and repeat. I was told the hospital had a policy

where the first leech had to be placed by a physician, and once it took to the patient, the following leeches could be placed by nurses, so we were there that morning to place the first one. The patient only spoke Spanish, so we had an interpreter via phone service help with informed consent. This is when things truly got weird. After the chief resident explained the plan,

the patient became very uneasy and upset. After a bit of confusion, we decided to wait for an in-person interpreter to try again. It turns out, during our literal game of telephone, the word leech somehow transformed into venomous snake. Despite taking Spanish in high school, I am not fluent, and I have no idea how this happened. So already off to a poor start, we spent some time basically finding different ways to say, no, it's not venomous snakes, it's just leeches.

Which I feel is like saying, no, no, don't worry, I'm not going to steal your car, just your engine and your tires. It's definitely better, but by how much? The misinterpretation was finally sorted out, and shout out to medical interpreters and all interpreters everywhere, we would be totally lost without you. And the patient finally consented to leech therapy. The resident then tried to place the first leech onto the area, but the leech had other plans and wasn't really into latching on at the time. During what seemed like hours but was probably just a couple of minutes, the resident tried again and again to get the leech to literally bite, to no avail. With everyone in the room singularly focused on the reluctant creature,

no one noticed that the cup with the other leeches, in his other hand, were as precariously tilted over the patient, and one adventurous leech had made its way to the lip of the cup and onto the gloved finger of the resident. Another resident in the room finally noticed and brought it to his attention. but instead of very calmly stopping what he was doing and making very simple movements to remedy this situation, his fight or flight response kicked in. He let out what I can only describe as a genuine shriek and inadvertently dumped the cup and its contents onto the patient's lap.

Needless to say, the patient was about as freaked out as humanly possible at this point. But we did eventually get the leeches to latch. unfortunately and independent of these hectic events, the tissue was too far gone, did not regain enough blood flow, and the thumb could not be saved. I wish more could have been done for the patient, especially under those circumstances, and I really hope they're doing well wherever they are. But I truly appreciate the experience to learn how leeches can potentially help us even in modern times. I just the the visual of like the the leech slowly making its way and then creeping up the cup the scream and the yeah the resulting chaos specifically that amazing first-hand account comes from friend of the pod Dr. Robert Rowe who is a preventative medicine physician who serves as

adjunct faculty with both the University of North Carolina Preventative Medicine Residency Program and the Gilling School of Global Public Health. He is also the creator and host of Tar Heel Wellness, spelled H-E-A-L, which is a podcast dedicated to the health and well-being of medical residents, and it touches on physical and mental challenges that many other people face as well, and it's available wherever you get your podcast. You should definitely check it out. Yeah. We're going to be on it at some upcoming time, I think, which will be really, I'm really excited about it. Yeah, it's going to be so fun. But yeah, I, what an amazing story. Thank you so much, Dr. Rowe. Thank you so much for not only telling us that story and then being willing to tell it again so that we could share it on the podcast because the first time we heard it, we were like, I'm sorry, that's too good of a story.

You please, please share. Yeah. Hi, I'm Aaron Welsh. And I'm Aaron Amman Updike. And this is, this podcast will kill you. Today's, as promised, an incredible companion episode to last week, all about leeches. Just when you thought it couldn't get simultaneously grosser and cooler, it's about to. Before researching for these two episodes, was there one or the other of these that grossed you out more, just like as a general thing? because I feel I have an opinion about that.

Oh, yeah. For me, it's maggots. Interesting. Yeah. Leaches, for some reason, absolutely creep me out. I don't think I've ever seen one in real life, but they just, I don't, something about the idea of them freaks me out. That is very interesting because I love them both so much now, like now, but I think I would still have a difficult time, like getting over. the visual of maggots. Leaches don't bother me. And maybe... Interesting. I don't know why. Also,

I need to apologize in advance to you because I have some gnarly leech facts that I've going to share with you. I can't wait. That may reinforce some of these leech wariness that you have. It's okay. I'm mostly a saltwater girl, so I think I'm going to be fine. You're not. There are saltwater leeches. This is going to be up there. Okay, because do you know the other thing that actually terrifies me more than anything in the ocean is snakes, like sea snakes? Oh, yeah. So now I get to also be afraid of sea leeches, apparently.

Are you afraid of terrestrial snakes? No, not at all. Love them. Okay, just sea snakes. Sea snakes. Have you seen them swim? Yeah, I have. And I also feel like there was a formative documentary that I watched probably on like animal planet growing up where it was like, sea snakes are the deadliest of all animals. And that is still what's burned in my memory is truth.

But today we're not talking about snakes. No. We're here to talk about leeches. Yes. And because this is a companion piece to last week's episode on maggots, which if you haven't listened to yet, oh my gosh, really don't be too discouraged or grossed out, well, that's kind of a hard thing to ask. But I promise you there are some really cool nuggets of information in the maggots episode.

But because this is a companion. opinion piece, we are doing one quarantini for both episodes because it is a tale of two worms. Get it? Huh? And in a tale of two worms, in case you missed out on the maggots episode, which again, go listen to it, you can find ingredients such as vodka, lime juice, cranberry juice, pineapple juice, pineapple juice, orange juice, ginger ale, basically fruit punch. Fruit punch. It's fantastic. The full recipe, it's already up on our website, this podcast, we can

dot com and all of our socials. So hopefully you've got one in hand for this episode. Yeah. Socials. Follow us on them. We've got some good content. Really? We really do. It's pretty cool. That's all I've got to say about that. But we also have a website where you can find all sorts of cool things including but not limited to transcripts, links to bookshop.org and our goodreads list, sources for all of our episodes, links to merch, links to our Patreon. links to a first-hand account form. You know, there's more stuff. There's so much.

Our website, check it out. This podcast will kill you.com. Yeah. Well, with that, should we get into leeches? 100%. We should. Right after this break. Dinner shows up every night,

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Visit blue apron.com slash terms for more information. Anyone who works long hours knows the routine. Wash, sanitize, repeat. By the end of the day, your hands feel like they've been through something. That's why O'Keefe's working hands hand cream is such a relief. It's a concentrated hand cream that is specifically designed to relieve extremely dry, cracked hands caused by constant hand washing and harsh conditions. Working hands creates a protective layer on the skin that locks in moisture. It's non-greasy, unscented, and absorbs quickly.

A little goes a long way. Moisturization that lasts up to 48 hours. It's made for people whose hands take a beating at work, from health care and food service to salon, lab, and caregiving environments. It's been relied on for decades by people who wash their hands constantly or work in harsh conditions because it actually works. O'Keefs is my hand cream of choice in these dry Colorado winters when it feels like my skin is always on the verge of cracking. It keeps them soft and smooth, no matter how harsh it is outside. We're offering our listeners 15% off their first order of O'Keefs. Just visit O'Keef's company.com slash this podcast and code this podcast at checkout. In 2023, a story gripped the UK, evoking horror and disbelief.

who should have been in charge of caring for tiny babies is now the most prolific child killer in modern British history. Everyone thought they knew how it ended. A verdict? A villain? A nurse named Lucy Letby. Lucy Letby has been found guilty. But what if we didn't get the whole story? The moment you look at the whole picture, the case collapses. I'm Amanda Knox, and in the new podcast,

doubt the case of Lucy Lettby, we follow the evidence and hear from the people but lived it to ask what really happened when the world decided who Lucy Lettby was. No voicing of any skepticism or doubt. It'll cause so much harm at every single level of the British establishment of this is wrong. Listen to Doubt, the case of Lucy Lettby on the Iheart Radio app, Apple Podcasts, or wherever you get your podcasts. So, leeches are actually worms. Surprise, surprise.

Specifically, leeches are a type of anilid worm, which are the segmented worms like your earthworms, worms that people know about. And there are a lot of different species of leech, the vast majority of which are either permanent or temporary external parasites. So they suck on blood, and that is what they live on. All of the ones that are used in medicine fall under the family Hyrudinidae, which suck our. blood, but also like amphibians' blood, they're pretty, like, they'll eat a lot of different things. And a couple of the most commonly used species in medicine are Herudo Medicinalis. What a, what a logical name. And several other species of Herudo as well, and then at least a few other species as well. In nature, like we're not grown in a lab, because spoilers, just like with maggots, the ones that we use in

medicine are all grown in a lab and they're all sterilized before they're used. But in nature, they tend to live in like warm, shallow, still pools, the types of habitats that amphibians prefer because amphibians are apparently quite a good food source for them. And leeches have, classically, if you think of a leech, if you've ever seen, what's that movie? Stand by me? Yes. I was thinking the same thing. That's what I think of when I think of leeches. Every single time, and he goes, bong, okay. So leeches have two suckers, right? They've got one on their front end and one on their back end.

And the front end is the business end. That's the end that we'll focus on. The posterior sucker, they use just for clinging and for moving. You like that? I do. I do. And while maggots that we talked about have no biting mouth of which to speak, Leeches, on the other hand, are equipped with not one, not two, but three jaws that are arranged like a pyramid.

Each one of these jaws has 60 to 100 teeth on them, Aaron. What? I know. It's terrifying. If you look at like close-up images of leech jaws, it is, they look like an alien. They look like they're terrifying. But that's why they leave. If you've ever seen a leech bite mark, it's like a little Y-shaped bite. It's because they've got these three jaws

that come together and take a whole chunk out of you. That's so cool. I know. And also cool are leeches themselves. Leaches, they're very fascinating. And the most useful part of leeches, medicinally is by far their saliva. Leach saliva contains over 100 bioactive substances. I'm sorry. So after they bite us with their like hundreds of teeth, leeches inject their

saliva into us and then they suck up our blood. That's what they're feeding on. When they do this, they're sucking up several times their body weight. in blood so that they can go several months, in fact, up to a year between blood meals. Erin. Erin. I have read, let me pull up my notes real quick, because I wrote this in a random spot. And I have just written, leeches live for 18 to 27 years in the wild. I love that you wrote that because I have, how long does a leach live for?

I still don't know, but they can fast for a year. and a half, what the heck. That is amazing. 18 to 27 years. Yeah, and now I'm about to fact check myself because I want to make sure that that has a citation involved. That's amazing. All right, so we did just do some fact checking. We fact checked. Because we couldn't resist. And years is definitely on the scale of years. Some sources say up to 20 years, I did find a couple sources that said that quoted the 18 to 27, and a lot of them also say like two to eight. So it seems like there might be a range, but it seems like the maximum lifespan in a suitable environment could be upwards of 20 years, which is, I mean, I never would have expected more than one year. Exactly. That's like

anything beyond a, I'm sorry, it's a worm. It's a worm. It's amazing. What's the longest lived worm, do you think? Someone let us know. Too many rabbit holes. Too many. Let's get back to leeches. They're sucking all this blood a whole bunch so that they can live their years in between blood meals. So for this blood to not just coagulate on removal from the body, which is what blood wants to do. That's what it does when it removes from the body. Leaches have a whole bunch of compounds in their saliva that function as anticoagulants. The first, most important, and most well-known and well-studied is called Herodin. It's like named after the leeches. And this, it's pretty cool. It inhibits thrombin, which if you want to throw all the way back to our hemophilia episode,

we talked a lot in that episode about the cascade of reactions that happens in order for our blood to clot. One compound has to be activated, which activated. it's another and on and on and on. Thrombin is one of the final enzymes in this cascade. So that is what Herodin is blocking. It's kind of like the bottom or top, depending on which way you want to look at it, of this cascade. And it's one of the major regulatory steps in coagulation.

So it's a really effective way to block coagulation. Herodin was synthesized via recombinant DNA, and it's used medicinally. Today, we use it all the time in medicine, especially if people can't use heparin, either because they've had a reaction to it or because they're allergic or for whatever reason. But that's not all. I said they have a hundred bioactive substances. They have a bunch of other substances that block other parts of the coagulation cascade,

like factor 10A, et cetera, blah, blah, blah. They also have a bunch of compounds that block platelets from aggregated. a la aspirin, which means that they're stopping that first part of the coagulation because platelets are one of the first things. But what it also means in us is that our wounds from a leech are going to ooze for a long time because platelets are one of the first things that we would use to stop and they injected that saliva into us. But that's not even all. They also have a whole bunch of other enzymes. Some of them, serve to increase the permeability of our connective tissue, which for the leach allows for their secretions to penetrate more deeply into our tissues so that they work more.

Medicinally, what this can do is promote resorption of fluid and blood because it's increasing the permeability of the connective spaces. They also have enzymes that help to dissolve any blood clots that have already. formed, and a lot of the things that they release, they're so much, helps with vasodilation and reducing scar tissue formation. Like, the list goes on, and we still don't know the mechanisms of every one of these compounds. There's also analgesic properties that we definitely don't understand, which makes the biting of those hundreds of leach teeth, or at least the sucking process a little bit less painful, perhaps. So you can imagine that with so many amazing

things present in their saliva, leeches are used for a pretty wide variety of things, or I should say they've been studied for a pretty wide variety of things. Because today, they're most often used for post-surgical care, especially in complicated procedures, like what we heard in our firsthand account with the reattachment of. a finger. They're for things like skin flaps, reconstructions, places where you really don't want a lot of venous swelling or a lot of edema, like overall swelling in the tissue, because leeches are really good at reducing that kind of swelling, both by physically removing that venous blood, but also by just reducing inflammation overall, and they leave these little wounds

open to ooze for a few days, which can also be beneficial. But leeches have been evaluated for a lot of other things that I found fascinating and would never have expected people to use leeches for. The one that has the most evidence thus far is in the treatment of osteoarthritis of all things. Huh. Yeah, that's my face too. So leeches have been studied for treatment of a lot of different kinds of arthritis, the idea being very strong. similar, that it's reducing inflammation around the joints, which is the cause of a lot of pain in arthritis. And a few, like, larger meta-analyses seem to show some benefit in osteoarthritis,

at least, for pain reduction and an increase in mobility. For other types of things like rheumatoid arthritis or even ankylosing spondylitis, there's been at least like case studies, not necessarily large studies. But people have also tried to use leeches. for things like migraines, TMJ, high blood pressure, heart disease, even some neurologic disorders. And at least the published studies on these seem to show benefit, but it's a really minimal amount of data for any of these other conditions. You're not going to find people who are going to give you leeches for your blood pressure. Like, that's not a thing. But for reconstructive surgery, it absolutely is a thing. Yeah. And some people have used leeches for the

of chronic wounds so you could use leeches and maggots together in harmony combination oh that's amazing i know that's that is leeches you know i love them their saliva is incredible it's magic yeah it's more powerful than magic it's nature so aaron tell me yeah Tell me about the history of these little suckers. Get it? Nice. Yeah, I can absolutely do that. Let's take a quick break and then I'll tell you as much as I can about leeches. Anyone who works long hours knows the routine.

Wash, sanitize, repeat. By the end of the day, your hands feel like they've been through something. That's why O'Keefe's working hands hand cream is such a relief. It's a concentrated hand cream that is specifically designed to relieve extreme, dry, cracked hands caused by constant hand washing and harsh conditions. Working hands creates a protective layer on the skin that locks in moisture. It's non-greasy, unscented, and absorbs quickly. A little goes a long way. Moisturization that lasts up to 48 hours. It's made for people whose hands take a beating at work, from health care and food service to salon, lab, and caregiving environments.

It's been relied on for decades by people who wash their hands constantly or work in harsh conditions because it actually works. O'Keefs is my hand cream of choice in these dry Colorado winters when it feels like my skin is always on the verge of cracking. It keeps them soft and smooth, no matter how harsh it is outside. We're offering our listeners 15% off their first order of O'Keefs. Just visit O'Keef's company.com slash this podcast and code this podcast at checkout. In 2023, a story gripped the UK, evoking horror and disbelief. who should have been in charge of caring for tiny babies is now the most prolific child killer in modern British history.

Everyone thought they knew how it ended. A verdict? A villain? A nurse named Lucy Lettby. Lucy Lettby has been found guilty. But what if we didn't get the whole story? The moment you look at the whole picture, the case collapses. I'm Amanda Knox, and in the new podcast, doubt the case of Lucy Lettby, we follow the evidence

and hear from the people that. lived it, to ask what really happened when the world decided who Lucy Lettby was. No voicing of any skepticism or doubt. It'll cause so much harm at every single level of the British establishment of this is wrong. Listen to Doubt, the case of Lucy Letby on the Iheart Radio app, Apple Podcasts, or wherever you get your podcasts. China's Ministry of State Security is one of the most mysterious and powerful spy agencies in the world. But in 2017, the FBI got inside. This is Special Agent Regal, Special Agent Bradley Hall.

This MSS officer has no idea the U.S. government is on to him. But the FBI has his chats, texts, emails, even his personal diary. Hear how they got it on the Sixth Bureau podcast. I now have several terabytes of an MSS officer, no doubt, no question, of his life. And that's a unicorn. no one had ever seen anything like that. It was unbelievable. This is a story of the inner workings of the MSS and how one man's ambition and mistakes

opened its fault of secrets. Listen to the Sixth Bureau on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. Before I get into the long, long history of leeches used in medicine, I wanted to first take a bit of time to just, get to know this group of animals a little bit more broadly. Okay. So much fun. And estimated 700 species of leeches have been described. Did you know that? 700. Yeah. And they can be found on all continents and seas, except Antarctica. They live in caves, in salt water, in fresh water,

in hot water, in freezing water, in shallow water, in deep water. The record is over 7,800 meters. What? I have to say, these last two episodes are making me feel like I did all of my invertebrate zoology classes poorly by not remembering any of this. Oh, if I once knew this, I have long forgotten it. Maybe I just never learned it, but like, ooh, okay. Keep going, please. Okay, okay. They, leeches also live in arsenic laced water and super alkaline water. not in water at all, but on moist land. It's pretty rad. Okay, a land leech. A land leech. And, okay, if we say picture a leech, most of us are going to picture those leeches from stand by me

that we talked about, or something very similar. But did you know that only about half of leeches feed on blood? No. I thought most of them dead. Half. Half. Half. Half. But are most of them still parasitic? Well, the other ones feed on things like earthworms, gastropods, crustaceans, and insect larvae. But not like as parasites, more as like just carnivores. Predators, yeah. Huh.

Yeah. One of the biggest leeches reaching length of up to 300 millimeters, which is nearly one foot, 11.8 inches. Uh-huh. preys on worms. It eats other worms. It eats other worms. But the biggest leech, I'm going to try to pronounce this, Hemantaria-Gillianii, gets up to 450

millimeters long, 17.7 inches, Aaron. That is very large for a worm. Nearly four inches in width. And this guy does feed on blood. Who's blood? Lots of different. types of blood. So humans have been observed, rabbits, cows, birds. Okay, but how do leeches find their prey, you might ask? They use many different sensory clues, as a matter of fact. So terrestrial

leeches sense things like ground vibrations, whether the leaves and dirt or whatever they're laying in gets moved around or disturbed, shadows, air currents. And maybe, although it's been debated, CO2 from the breath of their intended prey. Aquatic leeches use things like water currents or temperature or disturbance to detect prey. It's amazing. And I have several more, if you don't mind me sharing a few more cool bits of leech trivia. Okay. Please, leeches can live in extreme temperatures, not like the same leech or the same leech species, but for example, the freshwater leech, This is the names of these leeches, I'm telling you what, challenging. Ozo Brancis Jancianus, quote, survived at negative 196 degrees Celsius for 24 hours and up to 32 months at minus 90 degrees Celsius.

Wow. And on the other side of the spectrum, the marine leech, this is the hardest one of all. I think it's the last one. No, it's not. I see another one down there. Xelanacobdela Arugamensis has been found to survive at temperatures from 20 degrees Celsius to 40 degrees Celsius, which is 68 to 104 degrees Fahrenheit. Blood feeding leeches can also get creative with where they feed, such as up the nostrils or behind the eyeballs of humans and livestock. Did you just say behind the eyeballs?

Yeah, apparently. No, no. Uh-huh. at least like they go up the eyelid. Yeah. Okay. Uh-huh. Uh-huh. But I think the one, in terms of unique feeding location choices, the one that takes the cake is Placob Deloitte's Yeager-Skeldi, which I know that I totally did not pronounce correctly, but like, I'm sorry. This leech actively swims. It can actively swim, and it does this, swims to it. It's, It's hippopotamus host where it will invade the hippo's rectum and commence blood feeding.

Only in the rectum. Only in the rectum. Poor hippo. Yeah. But now that I've completely spent all of the goodwill that we had previously built up for leeches, let me attempt to like bring you all back on board. Get you to like a leech again? Yeah.

Yeah, I know that it's like we're, it's, it's an uphill battle, but I think that we can do it because I want to tell you about leech reproduction, especially parental care. What parental care? Exactly. See, Goodwill returned. So first of all, leeches have both male and female reproductive organs, which means that while they don't always or even often self-fertilized, they absolutely can, and this does happen. And second, leeches produce these things called cocoons, which come in lots of different textures, but that's where leach eggs develop inside this cocoon with like a nutrient soup that lasts until the eggs turn into juveniles and then can strike out on their own. It's so cute. But some leeches go beyond the cocoon. Leeches in the glossophonia day care for their eggs both before and after they hatch.

either in a little cocoon nest or on their body or in a little pouch like a kangaroo. Little kangaroo leech pouch? Uh-huh. If once the eggs have hatched, some leeches will bring them food like snails or mosquito larvae. Or, quote, by transferring nutrients across the body wall to the developing young in a manner reminiscent of a placenta. Oh. Isn't that amazing? But there's more.

Because researchers have observed that in times where food is scarce, some leach parents will starve themselves so that their young can feed. Wow. Some species live in groups with adults and young together sharing food and even caring for young that aren't their own. I don't think I ever thought about leeches, even worm, like behavior this much. I know. And it is incredible. I am in awe. interesting. Yeah. Yeah. The diversity found among leeches is incredible, and there are so many species that

haven't yet been studied or haven't been studied very much or have yet to be discovered. On their own, leeches are amazing. But if you want a human-centric perspective to convince you that leeches are worthy of study and conservation, consider the powerful anticoagulant herodin found in the medicinal leeches saliva and how it's now used in medicine. That's just one of the amazing compounds found in that leech species saliva. And there are many more leeches with many other cool salivary compounds like hementin, anti-coagulant found in the giant Amazon leech that targets fibrinogen formed blood clots, theramine, which inhibits thrombin like hurudin, but it seems to be different.

And then there's the bacterial endosymbiance of leeches. Leaches that feed on blood have bacteria that will help break down blood and provide essential vitamins. So if you want this human-centric reason for why preserving biodiversity is important, consider the leech, like not just the medicinal leach, but all leeches. But now, turning towards the medicinal leach, which actually turns out might be made up of multiple species or like morphs or something. Yeah. Yeah. Let's get into how humans have used these leeches throughout history. Okay.

Like maggots, the use of leeches in medicine goes way, way back. I'm talking 1500 BCE ancient Egypt murals in a tomb depicting the blood-sucking powers of a leech way back. Wow. Yeah. Ancient Mesopotamia, ancient India, ancient Greece and Rome, likely in ancient Central and South America, ancient China, there's evidence that leeches have been used medicinally all around the world for thousands of years. And this isn't a case of like an occasional mention or reaching for the leech only when everything else failed. Leeches were a very regular treatment in many places around the world for millennia so much so that, okay, the etymology does get a little tricky because when we were setting up for

this episode, I was like, let me just refresh my etymology notes and make sure that I am right in this. And it turns out I wasn't. It turns out the truth is a little more complicated. So my initial reading and a lot of papers will say that the word leach may have come from the old English word laissez-meaning physician. Turns out that there were two, from what I can tell, there's one paper that talks about there being two independent origins and meanings for that word lace or lace, a meaning, one meaning physician and one for leach. And then the two kind of merged. Because for a really long time, one of the synonyms for a physician was leech. Interesting. Because doctors used leeches so frequently. So it wasn't that like the name leech came from

doctors. It was like they called them the same thing because they, they used him so much, maybe? Yes. I think that definitely their meanings merged to a certain degree or something to that effect. I'll link to the paper that goes more into the etymology. But it's like we don't know which came first and whether leech was for the worm and then physician became known as a leech or leech became known from physician and it sounded maybe like the worm, something like that.

Okay. Anyway, it makes sense that the two would be synonymous. over much of the ancient world up until the 1800s or so because of what we know about medicine during this long period of time, i.e. that it was obsessed with blood and bloodletting. So these leeches took up residence as like a permanent tool almost in the phlebotomist toolkit. So I've talked about the humoral theory of disease like one million times exactly on this podcast. Exactly. So here's one million and one, just for a refresher. Essentially, there were thought to be four humors in the body, yellow bile, black bile, phlegal, phlegm,

and blood. Diseases resulted from an imbalance in the four humors. So that could mean too much blood, in which case you do some bloodletting until the balance is restored. In the bloodletters toolkit, you could find things like lances, little pocket knives called fleams, bleeding cups, syringes because certain situations required certain solutions. Many of these tools were just like a brute force attack. Like we need to get a lot of blood out of you and we need to do it now. Leeches came in handy when a gentle touch was warranted. When the desired volume of blood removed was on the order of milliliters rather than liters. Or when the area that needed bleeding was in. It was in. It was in. in a particularly sensitive or hard-to-reach zone.

Okay. Like in cases of hemorrhoidal congestion, rectal prolapse, vulval vaginitis, orky epididymitis, hydroceal, laryngitis, tonsillitis, Aaron, tonsillitis, what? Tonselitis. I know. Inflammation of the cervix. Ouch. Yeah, even some eye conditions.

Yeah. Ow, ow, ow. But even though it's like really hard to think about and makes me feel squirmy, this would have been less painful than like a blade on a spring, like some of these blood letters tools. Definitely. And like you mentioned, Aaron, leeches were also used for wound healing. Abdel-Latifal Baghdadi in the 12th century described how. how leeches were helpful in tissue cleansing after surgery, which is amazing. I love it.

And unlike maggots who, like we talked about, their popularity seemed to wax and wane over the centuries, leeches were just like on the up until the late 19th century. In the Middle Ages and Renaissance sometimes referred to as the golden age for bloodletting and leaching, leeches were used by barber surgeons who would have their patients grip a rod, which would possibly later inspire the barber pole, you know, like the poles that have, yep. So that might have been a symbolism for like grip the rod because this will cause your veins to swell and that'll make it easier for the leeches to latch onto to start the bleeding. Interesting. Yeah. And then just because I want to expand a little bit on the classic barber pole, because what else am I going to be able to do it

on the podcast? Okay, you can picture one, right? Like it has the pole, it has the spinning ribbon. It has the spinning ribbons, it has blue, red, and white often. Yeah. It has been suggested that the red ribbon, these all carry meaning. The red ribbon originally came from barbers advertising their services by wrapping the bloody linen from a former patient around the pole, showing, hey, we do bloodletting here. The red means, hey, I can bleed you. The white ribbon was, I can pull teeth and set.

bones. And the blue said, I can give you a nice trim or shave. Those were allegedly, it's one idea as to the possible origins of those ribbons. Isn't that great? What a wild time to live in, huh? I know. I know. I know. Wow. And so if you're like, okay, I really want to go get my haircut, but you see the barber pole just has red and white, like you're, you can get bled, but you're, you can get bled, you're not going to have a fresh. They're not going to do a trim. Okay. Yeah.

Anyway, as the popularity of leeches grew over the Middle Ages and Renaissance, so did its possible applications from neurological and psychiatric conditions like epilepsy to STIs, gastritis, diseases of the eye. I just keep seeing uterine applications mentioned. Ambois Parre, that French surgeon from the 1500s, he dedicated an entire chapter to leeches in his. massive treatise. And things were only going to get leachier. I don't know what exactly constitutes like the golden age of something, but I find it hard to believe that like that the Middle Ages

and Renaissance were the golden age when their popularity only continued to grow into the 1700s and 1800s to really unbelievable levels. So peak use was in the early 1800s. In Europe, physicians and barbers kept leeches handy in their offices. in leach jars. Some of these jars, Aaron, have you seen pictures of them? No. They're beautiful. They're like these beautiful ornate jars that have like carved little accessories with like gilded and whatever and it says leeches across the front of it. I went immediately went on eBay like in the middle of researching and I was like, I need to find an antique leach jar. I can't I can only find a replica, but it's going to be now my life's quest to find a leach jar. We should go back to the

Surgical Sciences Museum in Chicago, because I bet if they don't have it, they will know where you get at. A hundred percent. I love them. We'll post a picture because we have to. But perhaps no one loved leeches more than Francois Joseph Victor Broussay, one of Napoleon's physicians. Napoleon himself had leeches to treat his. his hemorrhoids. So cool thing. I feel like that would be effective. I think so too. Yeah. Has that, is that one of the proposed treatments for today? Uh, no. I mean, varicose veins, yes, but usually the legs. I think that we just have other options these days, but I didn't see anything about people using leeches like instead of surgery for hemorrhoids. So it's a good,

good thought. All right. Somebody proposed it. Maybe it's out there and I just missed it. Anyway, Broussay was such a fan of bloodletting and especially leaching that he was nicknamed, quote, the vampire of medicine. Love it. He thought that every disease was attributable to inflammation, especially of the GI tract. So like no matter what the condition, asthma, broken wrist, smallpox, sore throat, pink eye, it all came down to gas. astroenteritis. Of course. All of it. Logical. And so in one example I saw, he prescribed the patient a starvation diet and all of the

leeches that could fit on their abdomen, because that's where he thought that inflammation would come out of their abdomen. Oh, no. Somebody was described as looking like they were wearing, quote, a black glittering coat of male, end quote. Oh, gosh. Totally. Yep. And his enthusiasm for leech is may have been unmatched, but he was not alone in his love for them. Between 1829 and 1836, so over those seven years, do you have a rough guess as to how many leeches were used yearly in Parisian hospitals? Just in Paris. Yeah. You don't have to guess if you're like, I don't even know. I don't know. Hundreds of thousands? Five to six million each year. Stop it. Is that why they're basically extinct in the wild?

Yes, this is exactly why. This is why. This was a total of 84,000 kilograms of blood drawn annually. Unfathomable. It really is. Oh, wow. Millions more of the medicinal leech, the Heruda Medicinalis, were exported to the U.S. from Europe at one point 30 million leeches per year. Exported to the U.S.? Exported to the U.S.S. Yeah.

Oh, my. And so this huge demand, even at the time, drove leeches close to extinction, and rewards were offered for people who could find a way to breed them in the U.S. or find alternative species that were as effective without causing harm. Wow. Mm-hmm. And eventually this day. demand would die down as the medicinal leech faced the same fate in the late 1800s, as did

maggot therapy. Medical advancements like germ theory, a better understanding of human anatomy and physiology, and the use of statistics showing that bloodletting overall was useless to harmful for most conditions that it had been used for, all sent these leeches mostly packing with a few physicians hanging on to the practice. And also, I get that. Like, you have this beautiful Leach jar and you're like, what do you want me to do? Just like not use this? Put something else in it? No, thank you. I just keep one for just a couple of years and like, yeah, just use it every. Right. It's got to come back, right? It's just like low wasted jeans, low writers. It's going to come back. Those can't come back. It's terrible. I'm not happy about it. But anyway, also like the

maggot, the leech would experience a renaissance later in the 20th century. Barbers, because barbers surgeons and physicians, had noticed the anticoagulant effects of leeches for a long time, how like an area where a leech had been attached would continue to bleed longer than if the wound had been made by something else, like you talked about. And in the 1880s, researchers succeeded in extracting the substance that led to this anticoagulant effect, which was called Herodin in 1904. for decades, challenges with extractions, like how it would take an estimated 50,000 leashes a year to get enough herodin for scientific study, and that people who were treated with the extract experienced shock because it probably wasn't properly purified in its extraction.

This limited its use or investigation. But then, like you mentioned, Aaron, in the 1980s, researchers succeeded in engineering the substance, and that's allowed people to study this incredibly powerful anticoagulant for all kinds of applications. And leeches themselves have experienced a bit of renaissance in the field of surgery, especially plastic and reconstructive or microsurgeries beginning in the 1960s. In 2004 is when the FDA certified leeches as a medical device, and it seems like people are getting back on board with these powerful little parasitic worms. Like, I'm fully on board.

I feel like what it comes down to, not just with leeches, but with maggots too in terms of medicine, is that we don't always have to reinvent the wheel and that there may exist things that people have used for a really long time that could be really powerful. Or maybe they're not powerful, but also maybe we should check it out on like a case-by-case basis and see what we find. Because it could be something like leeches. It could be something like maggots. And I think that these past couple episodes have just been so thrilling and fun and interesting to put together. And I can absolutely say that I have so much more appreciation for both leeches and maggots. And now I can't pick a favorite.

Yeah, same. Like, I love that they both exist. I love that they both were, like, licensed by the FDA for use. I know. Fascinating. Yeah. Well, sources. Well, sources? I think so.

Okay. We can all learn more. We can. I am going to shout out too. So if you want to learn some more leach facts and that wasn't enough for you, which like... Like, who doesn't? Honestly, there's so much more in this great paper by Phillips at All from 2020 titled Leeches in the Extreme, Morphological, physiological, and behavioral adaptations to in hospitable habitats. Leach is in the Extreme.

I love that title. I know. And then the second paper that was mostly about the history of leeches in medicine was a paper by Montanari and Manelli from 2022 titled From Ancient Leach to Direct Thrombin Inhibitors and Beyond, New from Old. Fab. I had just a few papers and one book that I used predominantly one chapter of, and this book actually had some information about maggot therapy as well. The book was titled biotherapy, history, principles, and practice. And they had an entire chapter on herudotherapy or the use of leeches. And then a chapter on maggot therapy that I used a little bit of last episode. And then a few other papers on how leeches are used today and on all of the incredible

compounds that we found in their saliva and the future of all of that. But you can find the list of all of the sources from this episode and every single one of our episodes on our website, this podcast Willkillu.com under the episodes tab. A big thank you again to Dr. Rowe for just an amazing story. Such an incredible story. Thank you so much for sharing it with us. Thank you also to Bloodmobile for providing the music for this episode and every single one of our episodes. Thank you to Leanna Squalachi and Tom Brifogel for the audio mixing.

Thank you to Exactly Right Network. And thank you to you, listeners. You know, you made it. You did. Congratulations. What do you think about leeches and maggots? Do you have a favorite? Do you have a favorite fun fact? Do you have a favorite gross fact? Do you love them? Do you love them? As we love them. And as always, an extra thank you to our patrons. Thank you so much for your support. We really appreciate it. We do. Until next time, wash your hands. You filthy animals. I'm Clayton Eckerd in 2022. I was the lead of ABC's The Bachelor. But here's the thing. Bachelor fans hated him.

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