Sucking Saves Lives - The Bloodcurdling Story of Medical Leeches

For thousands of years, humanity’s favorite medical cure-all was a squirming, blood-sucking worm. Long before modern medicine gave us antibiotics, vaccines, or targeted therapies, doctors faced with everything from fevers and headaches to systemic infections reached for one trusted tool: Hirudo medicinalis, the medicinal leech.

In this episode of Dirt Nap City, we dive into the murky waters of history’s most infamous parasite-turned-physician. We explore the ancient practice of bloodletting and how the belief in balancing the body's "four humors" turned leech collection into a massive global enterprise. At the peak of "leechmania" in 19th-century Europe, tens of millions of leeches were harvested annually, driving wild populations near extinction and sparking a lucrative international trade network.

We’ll uncover the bizarre methods used to harvest these creatures—including workers walking into swamps to let leeches attach to their legs—and the gory details of how doctors applied dozen after dozen to desperate patients. But the story doesn't end in the Victorian era. In a surprising twist, we trace how these squishy invertebrates made a dramatic comeback in modern operating rooms. Today, FDA-approved medicinal leeches are actively deployed in microsurgery and reconstructive procedures to relieve venous congestion, using the powerful anticoagulants in their saliva to save reattached fingers, ears, and skin grafts.

Join us as we untangle the strange, slimy, and surprisingly sophisticated history of the world's most dedicated bloodsuckers. Did medical leeches truly heal the sick, or were they just an elaborate form of torture? Tune in to find out how a humble swamp dweller earned its permanent mark in medical history.

Transcript

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SPEAKER_01 0:04

Hey Kelly, you want to do a dead end? I always want to do a dead end.

SPEAKER_02 0:09

Let's uh let's get gross today. Gross as in disgusting or as in like the money you made before uh before expenses?

SPEAKER_01 0:19

Yeah, no, let's let's get disgusting today. You know, it when we were doing that Florence Nightingale uh episode, got me thinking a lot about healthcare back back in those days. And it was remember the whole theme of that episode was basically the you know, doctors didn't know what they know now, you know, and that wasn't even that long ago. So imagine going to the doctor in 1830 because you have a headache, and the treatment is here, we're gonna put these worms on your face. Oh, leeches? We're gonna talk about leeches today, Kelly.

SPEAKER_02 0:54

Uh, you know, I see you say this to me sometimes um that you you've been thinking about this one. I've got this on my list, but I've never had the I've never had the courage to do it.

SPEAKER_01 1:05

So uh I'm glad I'm glad you I'm glad you stepped up. Well, you know, there were a few options back then if you had something like a headache, and one of them was willow bark. You know, um there wasn't you know mod we didn't have a lot of pills or anything that you could take. No, willow bark ended up um in 1899, aspirin was invented as a byproduct of willow bark, and use willow bark for pain and fever treatment. So, you know, aspirin wait, wait, so this is just bark off a tree, yeah, from willow trees, right? And and all the and all the um components of that that eventually became uh I think silicin um became aspirin. So there were a few options, most of them natural kind of things, you know. But we think of leeches as some kind of medieval, you know, like superstition or some kind of you know, oh yeah, black black magic kind of thing. But it was mainstream, it was mainstream medicine, you know, in the 1830s. In fact, it was very popular, it goes all the way back to like ancient Egypt, but in 19th century Europe and the US, um demand for leeches was off the charts. Um at its peak in like 1832, 1833, we're talking, France was importing like 50 million medicinal leeches a year.

SPEAKER_02 2:33

Okay, so so question I mean, that's a lot.

SPEAKER_01 2:37

What exactly is a leech? Okay, a leech is like a a specific kind of worm that burrows that you can find like in the marshes and swamps. In fact, there were professional leech collectors. They didn't they it was really difficult to like breed these like in captivity, you know, like a hospital couldn't have a leech farm, they just had too many requirements in terms of like the climate and the the conditions, plus um they need blood to survive, so you would have to be feeding them blood in order to subsist. So there were professional special oh yeah, yeah, and a professional leech collector is just like you think they would wade into ponds and marshes and let the leeches attack their legs and attach to their legs, and then they'd come out and then they would like try to pull the leeches off of their bloody legs into a bucket, and they'd go back in the swamp and then they'd keep doing it and they'd sell them to hospitals.

SPEAKER_02 3:41

Um, I mean, imagine if your daughter was marrying a leech collector. Would you be proud of that? Would you honestly would you shake his hand? So have you ever had a leech?

SPEAKER_01 3:53

No, no, I've never had a leech, have you?

SPEAKER_02 3:56

I have, I have, yeah. What do you mean? Um when I went to camp in the Ozarks in uh Missouri, we would go kayaking in the Osage Forks River. And the Osage Forks River was a very brown, you know. I don't know that it was necessarily dirty because in the shallower parts you could see to the bottom, but um yeah, just kind of like clay and mud and you know, lots of mud in it, and and so not a lot of visibility. But we would we would canoe down this thing, and there was also a zip line and a couple of places with uh diving rocks that you would climb up on and jump off of. And I remember several times, you know, I went to this camp for a long time and was there all summer. I remember several times coming out of the water and having leeches on my legs and having to had having to pull them off, and they would leave it's it's like a little two little red spots that they leave where they where they attach to you.

SPEAKER_01 4:53

Gross. And did it bleed? Like is it like a mosquito where like you get it and then you're bleeding?

SPEAKER_02 4:59

Um, yes, yes. As I mean, I guess it depends on how long it had been attached to you and how deep it had gotten, but it would it wasn't it was never anything that I mean it kind of hurt to pull it off, but once it was off, it didn't hurt, it didn't itch, nothing like that. It just was two little, you know, like two little cuts on your leg.

SPEAKER_01 5:17

Well, the big place to find leeches in in Europe around that time was Ireland. Ireland had um, you know, abundance of native leeches and became a major source for European you remember when Arthur Guinness tried to make that uh leech, that leech ale um did not succeed. But you know, and um leeches were so popular in the 1830s that that at some point in the 1830s they like there was it was depleted, like there was a leech shortage, they just ran out of leeches. They had they had uh got them all for for medicine and they're over harvesting, you know, Spain. Um they basically ran out of leeches out of Spain.

SPEAKER_02 6:06

And uh I'm gonna guess, I'm gonna guess there were still plenty of leeches, they just weren't looking in the right spots, like Louisiana, you mean? Yeah, yeah. In the new world, there were lots of leeches.

SPEAKER_01 6:18

Well, yeah, it's funny because in my uh in my research on this, I I see a lot about Europe, about leeches coming from Europe, but nothing really about American uh leeches. But the populations got completely depleted, and then countries started importing them from different places, and that's when they got a little more expensive. But it was like a dot-com bubble, basically. Like, you know, it's just like they were really popular in the 1830s, they like hit a point and then they ran out. So the whole reason that leeches were used is a process called bloodletting. Have you heard of bloodletting? I've heard of it, I don't know what it is though. So bloodletting is the deliberate removal of blood from a person's body as a medical treatment. All right, okay, because the idea back then is they had this uh theory called humoral medicine, and humoral medicine was the idea that your health depended on maintaining balance of your bodily fluids, and the bodily fluids there were four that they were cared about blood, yellow bile, black bile, and phlegm. Like those were the four bodily fluids that they cared about. What about? And they had to be in balance. I'm sure you're gonna name a bunch of bodily fluids. We don't need that, yeah. But it's just like those were the four that they that needed to be in balance, all right? Okay, okay. And if you were sick, the doctors just thought, okay, well, you have too much blood. So we gotta unbalance that by getting rid of some of your blood.

SPEAKER_02 7:53

Well, it's not that the blood is bad or has a disease, it's that it's just too much. It's not out of balance.

SPEAKER_01 7:59

Okay, okay. The ratio between your blood, your yellow bile, your black bile, and your phlegm was too much. They couldn't just like ask you to spit and get rid of some phlegm, they had to like get rid of your blood because that's what you had most of, probably. Or they could just give you more phlegm and more yellow bile and more black bile, right? Because it never seemed to be an option. I'm a phlegm donor. If the doctors thought you had too much blood, they had two options. They uh well, they had three options cupping, which you see today still, you know, where they uh you see that like in a lot of eastern medicine or like acupuncture clinics or something where they'll have you have you ever done cupping? I've never done it, but I've seen the results of friends and family that have done it.

SPEAKER_02 8:46

It leaves little holes or little circles all over you.

SPEAKER_01 8:49

Yep. The other option would be they cut a vein and just let your you bleed out into a bowl. Basically, yeah. Now that's actually what happened to George Washington, and that's how he died, actually. Um lost too much blood. He in 1799 he had a throat infection, and they went in and they cut his arm, put him in a bowl, put it in a bowl, and then moved 40% of his blood. And uh God. I you know, I mean, it was all guesswork back then, right? I mean, they cut a vein, he lost 40% of his blood, and he died from a throat infection. Um, but the thing is, sometimes people did feel better from bloodletting, so they thought that it worked.

SPEAKER_02 9:37

How much of that dramatic?

SPEAKER_01 9:40

I don't know.

SPEAKER_02 9:40

You mean like the placebo effect? Yeah, just like people thinking, okay, I've I've I've released this blood, I'm gonna be okay.

SPEAKER_01 9:49

Right. Right. That's the thing, is that um you could maybe there's a little bit of that. I mean, if they're obviously though, if you're taking 40% of your blood, I don't placebo is not gonna save you, right? Yeah, true. But the idea maybe you do feel a little bit better, maybe you feel lighter, maybe and and actually, and we'll get to this in a second, there's actually some science behind it, and they still use leeches to the day, this day, but I'll I'll tell you more about that in a minute. Okay. So leeches were the third option beside cupping and cutting your vein, because leeches are just a biological bloodletting, you know, machine, basically, right? You'd get the typical patient would get five to ten leeches put on them, but sometimes twenty or thirty or even fifty, depending on what the the treatment is. And the cool part is the leech would um would get in there and um their saliva contains this um uh chemical called uh Herudin. Herudin and that's a coagulant, so which prevents your blood from clotting. So you take you the leech bites you, you take the leech off, and you keep bleeding.

SPEAKER_02 11:05

Wait, wait, wait. Coagulant is I thought coagulant caused it to clot. I thought it was.

SPEAKER_01 11:12

It's a anti-coit it it right. So it's in the prevent your blood from clotting. You you want you don't want your blood to clot. You want to keep bleeding. Okay. In this scenario, you want your blood to keep bleeding. I guess if you have if you have uh like arteries that are clogged or something like that, that could actually be good. Well, here's the thing is that sometimes, like after surgery, for example, and they were still doing surgery back then, just without any like modern they didn't know what they were doing compared to what we have now. But you know, sometimes after surgery, a piece of tissue might have good arterial blood coming in, but poor venous blood flowing out, right? And sometimes then the tissue gets like congested and then it dies, right? Um so what the leech can do is go in there and take out some of that trapped blood, let it flow again, keep the blood flowing. So that's they still use this today, like it's the most effective way to do that because their saliva has that herodin stuff. So the doctors were wrong about why leeches worked, but they were just kind of like Florence Nightingale, that like she didn't know why, like we didn't know why it worked, but they were on to something, yeah.

SPEAKER_02 12:33

Right. So so so wait, I gotta ask. Um, yeah, does does it not do do they not introduce any kind of disease into your veins? Like, is it is it sterile? In other words, because you know, like from mosquito, you can get West Nile or you can get yeah um viruses, but I think that was okay.

SPEAKER_01 12:54

The problem, I think, was that they reused leeches. I don't think, you know, especially when they were running out, when you know, I I don't think the 50 million where they would put it on and then throw it away. I think they would try to reuse them, especially when there was a shortage. And you can imagine this sounds like a this sounds like a um uh a Monty Python sketch, you know, like are they are they fresh leeches? You can imagine you're going in for heart surgery, then they put the leech back into the bucket, and then I go in for leg surgery, and now our blood, your blood is contaminating mine, that's probably not great. Yeah, um, so by the turn of the century, like by the early 1900s, they'd kind of become outdated once we started learning about germ theory and all that, but then they came back, and so as like reconstructive surgery started getting popular, uh like it is now, um for all the reasons I just said, they still use, especially when the tissue has that venous congestion, you know, coming from that the bad blood from the venous from the veins. So the FDA to this day still classifies leeches as a medical device. They did figure out that the herodin, they figured out that that was the secret sauce in the leeches, and that led to modern anticoagulant drugs that they that they have today. So, you know, we did learn something from them, but actually to this day, we still like you if you're going in for surgery, you may get leech. I don't know if they I mean I'm sure they'd have to tell you, right? Uh yeah, I mean you would see part of the paperwork that you signed.

SPEAKER_02 14:45

You would see those two little two little spots, and you'd say, What was that? So, so are they are they a special kind? Or is is are there like different um yeah varieties of leeches?

SPEAKER_01 15:00

There are. There's there's two different there's two different kinds, and one, or actually there's like four different kinds, I think. Um, and one of them is good and the other one is is not as good. The medicinal ones um are you know the a a specific kind.

SPEAKER_02 15:18

Um so you have to specify medicinal leeches. I want medicinal leeches, not the not the bad leeches.

SPEAKER_01 15:27

Yeah, I mean, I don't think you have to I don't think the patient has to specialize. But there but back in the day though, you did. You probably had to pay more. Herudu medicinal medicinalis is the medicinal ones. And what was happening, they were trying to get ahead of like the shortage, so g geneticists were trying to lump them together, Herudo Verbana in southern Europe, and they were selling it as a medicinal leech, but it wasn't exactly that one, it was like a substandard leech. Um I don't know. I mean, I think it's all pretty, you know. If there's money involved, someone's gonna have a counterfeit version of it, right? Right, right. You could buy those down in Mexico, so they probably weren't as or Spain in this in this case, yeah, yeah. Um, and they were the ones counterfeiting it. Um, and and Eastern Europe. So, yeah. Um leeches. So would you be upset if you went in for surgery and would you want to be told, or would you want to be like, just do whatever you it takes?

SPEAKER_02 16:42

So so I've had leeches before. I'm not I'm not that grossed out by them, you know what I mean?

SPEAKER_01 16:47

It's not but you haven't had them in a hospital, like that's just no some sort of sterility.

SPEAKER_02 16:54

Yeah. And and and no, I wouldn't be upset. I would I'd want to be told, you know, I'd want to know what's going on. But at the end of the day, if that's what it takes, if that's the thing to do.

SPEAKER_01 17:04

If you were told if you had to sign a consent for him to get to do leeches, would you be like, no, I'm not doing that? I would sign it.

SPEAKER_02 17:12

I would sign it. The the special I mean, just for the story, Alex. We've already established that I let dogs drink milk out of my mouth, so a leech is not a big deal. So if the doctor says I have to run to the bait shop real quick, hold on. He's casting a line. I mean, yeah. They're they're they're kind of like slugs, right? They look like slugs, but they have teeth.

SPEAKER_01 17:33

Yeah, I mean, I think they're bigger, I think they're thicker and longer, like uh a big, big uh worm. Yeah, uh gross.

SPEAKER_02 17:42

I told you we're whatever it takes. You you were right, you're right. Uh thank you for thank you for doing that so I don't have to do it now. That episode.

unknown 17:50

All right, bye.

SPEAKER_00 17:51

Hey, hey, don't squirm the glass fish by the window. Little wiggles black and green.