February 6, 2014 • 23 mins
The Power of Leeches: Are leeches mere bloodsucking parasites or do these creatures have a place in modern medicine? Plus learn about the very real 19th century invention that incorporated bottled leeches. Tune into this episode of Stuff to Blow Your Mind for all sorts of vein-tapping goodness. Image credit: Garry DeLong/Oxford Scientific/Getty
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Speaker 1 (00:03):
Welcome to Stuff to Blow your Mind from how Stuff
Works dot com. Hey, welcome to Stuff to Blow your Mind.
My name is Robert Lamb, and I'm Julie Douglas. Julie,
I want you to imagine an alternate universe not that
far removed from our own. Everything's pretty much like it is,
(00:23):
except instead of depending on save batteries for our power,
depending on electric circuits, we depend on blood sucking leeches.
I thought you were going to say potatoes or onions. Well,
that's that's another that's another multiverse. They're infinite multiverses involving
various substances of power, alternate energy, but in this case,
(00:43):
blood sucking leeches. All right, well, I guess you know,
a long time ago, this actually was something that was
a universe in place where our ancestors in which they
did depend on leeches. Yeah, yeah, for ages and ages.
Of course, you know, leeches were used in in in
medicine just to cure about anything, and we'll get to
that in a minute. But but the the key point,
(01:04):
the key Victorian point where you can sort of imagine
this uh alternate universe of leech power breaking off and
becoming real. We can we look back to a particular
invention by the name of the Tempest Prognosticator. This was
developed by Yorkshire's George Merryweather and it showed up in
the Great Exhibition at London's Crystal Palace in eighteen fifty one.
(01:27):
Now this is a device that ended up not making
a splash. Didn't really impress anybody then, Uh, the science
didn't hold up. But it was grounded in the idea
that leeches consents impending changes in the weather via changes
in the electromagnetic state of the atmosphere. Ah, so sort
of a barometer of sorts. Weather thought, And I love
(01:48):
the name of a tempest prognosticator. Yeah, Like even as
he was naming it, he wanted to get a little
away from the leach aspect of the invention. Um, it's
it's it's a beautiful invention. It looks kind of like
a like a crystal chandelier if that chandelier had little
tubes with leeches in them, or or Merry go round
and instead of magical horses, you had glass vials filled
(02:11):
with leeches. That's what I had described it to myself
as is this kind of tiny ornate iron carousel with
these twelve glass jars that were fitted around the carousel,
and then each of those contained a leech, and according
to Professor Mark Settle he's also a curator for the
American Museum of Natural History, the glass was to be
transparent so that the leeches could see each other and
(02:32):
agree amongst themselves as to the prognostication. Yeah, you need
a leech quorum to be to be met. And this
this is how they would tell everybody whether or not
the weather was changing. If any leech climbed up and
into the escape tube, its weight would dislodge a piece
of whale bone, which would release a hammer that would
ring the bell announcing inclement weather. Is on hand, I
(02:56):
love it. I love the simplicity of it. But yet
it's it's all hinge ng on the idea that these
these leeches a are are tuned to these electro electromagnetic
forces in this very specific way, and that they are
looking to each other for guidance. Uh, that there's some
sort of a social hierarchy within the leech society that
(03:16):
will come into play and make this device work. Well,
it's kind of like the special order of weather monks
among leeches, right, Um, I mean that's with Crystal Palace
eighteen fifty one. That is one place I've always wanted
to time travel too, and now even more so because
think about all of these wacky things that you've got to,
not only the Crystal Palace itself, it was just an
(03:38):
amazing piece of architecture. Yeah, and so so many of
those invations there would have each been a portal off
to a different multiverse verse had it really taken off.
So you're saying there's a possibility that I could somehow
time travel there? Is that what you're saying, Well, maybe
maybe that's that's a whole another podcast, right, but maybe Okay, Well,
the point of this is that obsession abounds with leeches,
(04:00):
and for good reason. We will find out because leeches
have some really important properties. But first let's discuss what
they are as an organism. What is a leech really? Well,
when you're talking about a leech, of course, you're talking
about hundreds of species. Some people currently there's you're looking
at account between six hundred and seven hundred species, but
some people think there could be as many as ten
(04:21):
thousand species out there in the world. Because we're discovering
new species of leech on a pretty regular basis here um.
So they range in size from leeches that are just
over just a one centimeter in length to twenty five
centimeters in length UM. Some of them actually are not
blood suckers. Some feed on decaying plant material. But it's
(04:42):
the more famous kinds that that we tend to associate
with leeches, the blood suckers, right, especially those that attached
to human skin. Those are the ones most of most
interest to human beings. Those are the ones we are
most familiar with. And what we're talking about here nuts
and bolts. A blood sucking animalid worm, and as you say,
they can grow up to about twelve inches, and not
all of them are sanguivorous. That's the term for blood suckers.
(05:07):
One of the best known leaches is called the medicinal leech,
and it has a sucker at each end of the
underside of its body. One sucker at the end contains
the animal's mouth and the other sucker acts as a
suction cup when the leach attaches itself to its victim,
and once attached this is so great. The leech slashes
its victim's skin with its sharp teeth and sucks the
(05:28):
blood and it injects the wound with a substance that
keeps blood from clotting. Really important. We'll talk about that later. Yeah,
hirodo medicinalysis, the medical leach. I also love that it's
it's it's three jaws. Now, not all leeches have three jaws.
Some have to to to jaw leeches. That's gonna make
a V shaped wound, But the three jaws make this
(05:50):
Y shaped wound for sucking. Now, you see them on
the land, you see them on an arm or something,
and they look kind of slow and wiggly, just some
sort of you know, just sting worm that can't move
around all. They much been in the water. That's where
they can really move. They use this undulating motions, wave
like like motion to propel themselves through the water. And then,
(06:10):
like you said, they attached on they feed and while
they're feeding, well basically they are two different acts that
this applies to, but feeding and mating. Once they've started
on that, you can actually cut a leech in half
and it won't notice. It'll just finish because they really
they're the laser focused on the zone, right, they're in
the zone. Yeah, And another thing is that they don't
(06:32):
just fill up with blood and as we do when
we fill up with burgers or whatever, just kind of
groan and and fall asleep. That's because the blood never
really coagulates. They've got the anti coagulating agents that is
circulating around in their body. So it's not like they
sit there and they become a lump and they just
you know, hang out for eighteen months asleep, although they
(06:53):
can subsist for eighteen months without food. But they are
quite mobile even with these really full bellies. Yeah, they
don't eat for a long time, but when they do eat,
they really go for it. They'll remain in place for
thirty minutes to six hours or more, filling up with
a blood and if they can. For instance, you can
take four or five leeches attached them to a rabbit
(07:14):
and drain the life from it in just half an hour.
That's how quick. And they can reach eleven times their
actual size, uh, their their normal size as they bloat
up on that blood. Pretty convenient right now, they have
to make every every meal count. They'll attached to skin,
but they've also been known to attach to eyeballs, uh,
orifices in the throat um. There's a there's an account
(07:38):
Napoleon's troops were marching from Egypt across the Sinai Peninsula
to Syria, and so they're they're really parched. They've come
across some water. They just fall upon it to start
drinking as much as possible. But there were leeches in it,
and so a number of the soldiers end up with
leeches in their throat. There's some swelling, there's some choking,
there's some death. Really her into stuff. All right. Well,
(07:59):
let's add to a nightmare fuel by describing one leech
species in particular which is fairly new to the roundup
of leeches. And Uh, we're talking about a leech that
goes by I don't on the street name of the
t rex leech. Yes, we're talking about Tyronto bidella rex,
the tyrant leech king. Uh. This guy reaches up to
(08:20):
forty four point five millimeters in length and goes right
for the body orifices of specifically the nose in the mouth.
Um and uh, most generally it's feeding on aquatic animals,
aquatic mammals rather uh and again go to the nose,
the mouth and then they'll name me. Stay there for
a week at a time, feasting. Yeah, this was discovered
(08:40):
in two thousand and ten, uh in the Upper Amazon,
when scientists plucked from the nose of a girl one
of these t rex is who had recently been bathing
in a river. So if that's not all just kind
of like, okay, that's that's slightly uncomfortable. And now consider
that the t rex has ferociously large teeth lining a
(09:01):
single jaw. So this is an even even different variation.
We have the three job, we have the two job,
and now this is the one job leech, but with
the teeth to make up for it. Well, and it's
it's uh, it's even more dramatic. We see pictures of
it because really we're talking about a leech that is
less than three inches long, and then you see the
teeth in comparison, and it's just kind of recoil a bit.
(09:22):
But the t retch leech uses its teeth to saw
into the tissues of mammals orifices. So again we're talking
eyes eurefas rectum's jos sawing into it with its teeth.
All right, Well, on that note, we're gonna take a break,
and when we come back, we're going to discuss the
role of the leach as the healer and uh also
look a detective. All right, Now that you've had a
(09:54):
palate cleanser with stamps dot com and we can get
away from the old t rex, let's talk about leeches
back in the day. Yeah, so leeches, they've been used
in medicine for thousands of years and the once once
believed to remove illness causing humors from the blood. So
this is based in and very uh non scientific ideas
about how the body works. I mean, some of the
(10:15):
arguably the best ideas of the time, but still ideas
that did not hold water. These are the humors of
the body. We're talking about phlegm and blood and file.
So the idea is that you let someone bleed a
bit and that helps to balance out those different humors. Yeah,
your humors are out of whack and you need to
get rid of the bad blood. So yeah, you end
up treating everything from gout to flash once to mental
(10:37):
illness with a hefty dose of leeches. Uh. It's it's
interesting that the word leech itself is derived from the
Anglo Saxon word looks to heal, and medieval doctors actually
called themselves leeches, which is interesting because I've run across
that before, and I thought maybe it was used mockingly,
you know, to say, oh, well he's just a leeches. No, no,
I think with pride, I am a leech. What can
(10:58):
I do for you today? Uh? Yeah, physicians applied lea
just to areas like the gums, lips, the nose, fingers,
and even quote the mouth of the womb, according to
a medical text from So why would they do that?
Because granted, there are a lot of crazy ideas that
have become that have had their day in history treating
using some sort of natural creature or a derivative in
(11:20):
in order to attempt to treat some sort of malady.
But in this case, we're coming down to two key
things about the leach. First of all, when a leech
attack attaches, like many parasitic organisms, it uh, it is
desensitizing the sensations, so you're not feeling the pain of
it actually uh slicing into your flesh for a meal.
But then, of course the other thing is your wound.
(11:41):
This freshly cut wound is a font from which this
leech wishes to drink and does not want that font
to close before it has had its fill. So the
leech has um an anticoagulant in its saliva as well.
That prohibits the the the coagulation of blood keeps it flowing. Okay,
So it's a end way to blood let someone because
(12:01):
they can't really feel it, and it's a way to
keep that blood flowing too. Damaged tissues, right, So it
gives a fresh supply to any sort of damaged tissues.
And here's the thing. It became so popular in the
nineteenth century that the species became endangered in Europe. In
eighteen thirty three, French doctors imported forty one million, five
hundred thousand leeches. Yeah, I was reading how in the
(12:25):
nineteenth century had governments that were imposing carraffs and trade bands.
There was a leech smuggling operation on the Russian border,
and and this was all the more difficult to because
of the time. Breeding efforts weren't all that successful, so
you just had leech catchers going out into the wild
and just harvesting them, to the point that that the
medicinal leech was in danger of extinction at one point,
(12:46):
and to this day it's it's rarity in the in
the wild is partially attributed to over harvesting. So you know,
physicians of old were sort of onto something, right, this
idea that maybe this could help in terms of bringing
fresh blood to damage tissues. On the other hand, you
have to say that the leech's ability to cure or
(13:08):
wildly overseated, so flatulence probably not cured by this. In fact,
a lot of stuff that they used it for, um,
And that's kind of what we think of today, is
that this was this barbaric use of leeches. It's like saying, oh,
I have a migraine, Well, let a wolverine chew on
your leg and you'll get over that kind of thing.
But no, that does not work. It doesn't work. But
(13:29):
at heart, that the end of the reason, like the
core reason that the leech does have a place in
modern medicine is that at heart, as a parasite, a
leech is a manipulator of human physiology, much like a
doctor in in in a very broad um scheme of things.
So if you want to manipulate the way tissues work,
(13:50):
a lot of times we're always looking to nature for examples,
for for some bio inspiration on how nature has evolved
to tackle a problem. So here's a case where this
teacher has evolved over millions of years to uh be
an expert at manipulating blood flow through tissue. And so
when a doctor, a modern doctor, needs to manipulate blood
(14:12):
flow through tissue, we turned to the leech. That's right,
and that's why they are now the comeback kid. And
now they are the symbiotic sort of parasite as as
opposed to one that's just uh one that we should
fear and that seems barbaric. In medieval medicine, Yeah, for instance,
tissue grafting and limb reattachment surgery, this is a big one.
Surgeons sometimes use the leeches to remove pools of congested
(14:35):
blood from swollen areas that interfere with the circulation and
can cause tissue death following surgery. Um. So this in
addition to the way that the the herodin the intercollegulate
prevents clotting in the local anesthetic in it that that
also features some antibiotic properties. Yeah, and this uh actually
sort of came to light more in a case in
(14:56):
nine five in which there was a harder toward physician
who was having a hard time reattaching the ear of
a five year old child. The tiny veins kept clotting,
and so it's really difficult to try to um reattach
something with these minute veins, right, so the physician thought,
maybe I'll use a leech and lo and behold he
(15:18):
did it. It helped those tiny little minute veins to
get fresh blood, and the ear was saved, and people
began to reconsider the leecher's role in medicine. Yeah. And
and as as your point out a specifically with microsurgery,
where you're dealing with these tiny blood vessels that that
are very difficult to manipulate. Yes, since then, lee just
(15:39):
have helped to save lives and limbs, reducing severe and
dangerous venous and gorgement post surgery and fingers toes, ears,
scalp reattachments, limb transplants, skin flap surgery, and breast reconstruction. Yeah.
And and there are other areas where that where researchers
are looking at possible applications. UM. For instance, uh uh.
(16:02):
Andreas Michelson, a researcher at the University of Duisburg Essen
in Germany, suggests that leech therapy may lessen the pain
and inflammation associated with osteo arthritis. Um. You know this,
of course, is a debilitating disease where the bones can
grind against one another and the cartilage is worn down
over time. So in order to get medicinal leeches for use,
(16:23):
how do you how do you go about it? Still
collect them in the backyard. Well, collecting leeches is one way,
and certainly leeches are collected, I should point out not
only for medicinal use, but also is bait and fishing.
And in order to collect leeches, I was I was
thinking maybe it involves some you know, hard on his
luck individual just taking a dive into the leechy waters
and then coming out and plucking them off. But generally
(16:44):
what it involves is like beef kidneys in a bag.
Just put beef kidneys in a bag. They go for it.
Like I said, their their their taste is rather simple.
So in a sense they're rather easy to catch. That
sounds about right, Yeah, beef kidneys in a bag that
they are then submerged into water and then the leeches come.
Then you can the bag out and you've got a
bunch of leeches, all right. So I wonder if that's
one of the techniques that bio Farm, which is a
(17:05):
company based in Britain, uses because they are the go
to source for leeches in the medical community, and they
provide tens of thousands of leeches every year to hospitals
and dozens of countries, and two species are commonly used
in leech therapy, and they can last for about up
to ten days. Okay, so they're definitely male safe. You
can send them to the mail. They're males. Now. The
(17:28):
downsides here are that sometimes they slip off patients and
they reattach themselves in unwanted places. Yeah, it's a bit
like hurting kittens in some respects. They have to just
you have to put gas around the surgical side and
just really limit where they can go and say this
is the only spot you're allowed to feed from right here.
This is the one second down side. They fill up,
(17:50):
they get full, they fall off. Yes, okay, of course
you can replace that one with another one. But for
those who just cannot even stand the idea of a
leech sucking on them, even though it might save their life. Uh.
There is Nadine Connor who is a University of Wisconsin
atmos and scientists who in two thousand and one helped
develop a mechanical leech. The device looks a little bit
(18:13):
like a small bottle attached to a section cup, and
it delivers that anti coagulating drug. Then the most important
part right to damage tissue and then gently sucks out
as much blood as needed, never drops off and says, oh,
I need a nap. So it's like all the power
of the leech, but without the having to deal with
the drama and the attitudes and the prima donna of
(18:35):
the leech. Yeah, there's no like separate dressing room. It's
just it doesn't care. This mechanical leech. Now, another advantage
of the mechanical leech is that up to twenty of
patients that are treated with real leeches developed infection caused
by aeromanus hydrophilia of bacteria that leaves and lives in
the leech is gut. And these infections are easily treated
(18:56):
with antibiotics. But again, it's another reason to ry and
remove ourselves from having to depend on a natural parasite. Indeed,
if this hasn't changed your ideas of leeches or you know,
cast it a new light of how leeches can operate
out there in the world, you have to consider this
next scenario. Uh, it's a it's a bit like Sherlock Leach, right,
(19:19):
Sherlock Leach. Yes, you can imagine the leech creeping onto
the scene of the crime and you know, wearing the hat,
smoking the pipe, playing the violin. It's not quite like that.
So about ten years ago, uh, we had this guy
named Peter Cannon and uh, this is in Tasmania. He
ties up a seventy one year old woman in a
remote home, steals several hundred dollars in cash, and uh,
(19:43):
the thing he doesn't realize that he's committing this crime
is that he has a leech attached to him. And
it is and this is luck would have it. It's
just finished feeding on him as he's perpetrating this crime
and does what a leech does when it's filled up,
It drops off and then he takes off. Right. So
this scene of the the scene of the crime. So
you can imagine the detectives coming in. They're looking around
(20:04):
and then somebody thinks to themselves, hey, there's a full
leech on the ground. I wondered that as anyway involved.
And because they all checked themselves and said, I don't
have lee, you know that the victim of the crime
doesn't have any leech bites. So where did this mysterious
leech come from? That's so that's clearly bloated on blood. Well, Uh,
the case had remained unsolved up until forensic experts extracted
(20:27):
DNA from the leeches gut contents, and then they matched
up fingerprint profiles to those on a record for Cannon.
Peter Cannon, the perpetrator here, and then he ended up
leading guilty and and they had him. Yeah. I think
this is such a great story because here's this jerk
who tied up this old lady. Thought he was being
really clever. He was probably on foot going through the bush,
(20:49):
got one of these leeches stuck to him, made off
scott free. He thinks that. Eight years later he gets
hold over. I think it's for a drug offense, right, Yeah,
he gets cross checked with that database. Bam. Detective Leech
is on the case. I wonder if they let into
it by saying, so, Mr Cannon, have you ever had
a leech attached to your body? And he's stone for
a curve, like, what what can they possibly have on me?
(21:12):
And then the leech they bring the leech in, the
leech like points at him through the class. I think
that's the one exactly what happened. I think he had
a pipe in the hat and everything. It's elementary nice,
all right. Before we leave this topic that I would
do want to mention I mentioned that that to overharvesting
of reaches leeches is one of the reasons that medicinal
leeches are rare in the natural world today. Another suspected
(21:36):
reason is that when leeches are young, they can't yet
attach to larger mammals. They have to attach to frogs.
So one theory is that as the as the frogs
become more scarce, then it's harder for young leeches to
get those first couple of meals that they need in
order to reach adulthood. So there you go. I mean,
that's another case for the circle of life and how
(21:58):
everything effects everything else, right, yeah, and uh, and that
includes the leach. So yeah, we hope that you feel
a little, uh, a little more informed about the leech
and about the use of leech, of the leech in medicine.
And certainly the next time you say watch stand by
me or just go swimming in the local watering hole,
you'll you'll reconsider that lovely creature that has perhaps attached
(22:21):
to your body if you want to learn more about
leeches and everything else that we cover, well you can
get somewhere very special. Yeah, go to stuff to Blow
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(22:43):
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And Hey, if you want to get in touch with
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on one way, well Julie has the answer for it.
That's right. If you want to tell us in detail
about your own leech stories, especially Robert, I know he
wants a lot of detail on to attaching to your mind. Um,
you can describe it and then send it to blow
(23:05):
the mind at discovery dot com for more on this
and thousands of other topics. Does it how stuff works
dot com
Welcome to Stuff to Blow your Mind from how Stuff
Works dot com. Hey, welcome to Stuff to Blow your Mind.
My name is Robert Lamb, and I'm Julie Douglas. Julie,
I want you to imagine an alternate universe not that
far removed from our own. Everything's pretty much like it is,
(00:23):
except instead of depending on save batteries for our power,
depending on electric circuits, we depend on blood sucking leeches.
I thought you were going to say potatoes or onions. Well,
that's that's another that's another multiverse. They're infinite multiverses involving
various substances of power, alternate energy, but in this case,
(00:43):
blood sucking leeches. All right, well, I guess you know,
a long time ago, this actually was something that was
a universe in place where our ancestors in which they
did depend on leeches. Yeah, yeah, for ages and ages.
Of course, you know, leeches were used in in in
medicine just to cure about anything, and we'll get to
that in a minute. But but the the key point,
(01:04):
the key Victorian point where you can sort of imagine
this uh alternate universe of leech power breaking off and
becoming real. We can we look back to a particular
invention by the name of the Tempest Prognosticator. This was
developed by Yorkshire's George Merryweather and it showed up in
the Great Exhibition at London's Crystal Palace in eighteen fifty one.
(01:27):
Now this is a device that ended up not making
a splash. Didn't really impress anybody then, Uh, the science
didn't hold up. But it was grounded in the idea
that leeches consents impending changes in the weather via changes
in the electromagnetic state of the atmosphere. Ah, so sort
of a barometer of sorts. Weather thought, And I love
(01:48):
the name of a tempest prognosticator. Yeah, Like even as
he was naming it, he wanted to get a little
away from the leach aspect of the invention. Um, it's
it's it's a beautiful invention. It looks kind of like
a like a crystal chandelier if that chandelier had little
tubes with leeches in them, or or Merry go round
and instead of magical horses, you had glass vials filled
(02:11):
with leeches. That's what I had described it to myself
as is this kind of tiny ornate iron carousel with
these twelve glass jars that were fitted around the carousel,
and then each of those contained a leech, and according
to Professor Mark Settle he's also a curator for the
American Museum of Natural History, the glass was to be
transparent so that the leeches could see each other and
(02:32):
agree amongst themselves as to the prognostication. Yeah, you need
a leech quorum to be to be met. And this
this is how they would tell everybody whether or not
the weather was changing. If any leech climbed up and
into the escape tube, its weight would dislodge a piece
of whale bone, which would release a hammer that would
ring the bell announcing inclement weather. Is on hand, I
(02:56):
love it. I love the simplicity of it. But yet
it's it's all hinge ng on the idea that these
these leeches a are are tuned to these electro electromagnetic
forces in this very specific way, and that they are
looking to each other for guidance. Uh, that there's some
sort of a social hierarchy within the leech society that
(03:16):
will come into play and make this device work. Well,
it's kind of like the special order of weather monks
among leeches, right, Um, I mean that's with Crystal Palace
eighteen fifty one. That is one place I've always wanted
to time travel too, and now even more so because
think about all of these wacky things that you've got to,
not only the Crystal Palace itself, it was just an
(03:38):
amazing piece of architecture. Yeah, and so so many of
those invations there would have each been a portal off
to a different multiverse verse had it really taken off.
So you're saying there's a possibility that I could somehow
time travel there? Is that what you're saying, Well, maybe
maybe that's that's a whole another podcast, right, but maybe Okay, Well,
the point of this is that obsession abounds with leeches,
(04:00):
and for good reason. We will find out because leeches
have some really important properties. But first let's discuss what
they are as an organism. What is a leech really? Well,
when you're talking about a leech, of course, you're talking
about hundreds of species. Some people currently there's you're looking
at account between six hundred and seven hundred species, but
some people think there could be as many as ten
(04:21):
thousand species out there in the world. Because we're discovering
new species of leech on a pretty regular basis here um.
So they range in size from leeches that are just
over just a one centimeter in length to twenty five
centimeters in length UM. Some of them actually are not
blood suckers. Some feed on decaying plant material. But it's
(04:42):
the more famous kinds that that we tend to associate
with leeches, the blood suckers, right, especially those that attached
to human skin. Those are the ones most of most
interest to human beings. Those are the ones we are
most familiar with. And what we're talking about here nuts
and bolts. A blood sucking animalid worm, and as you say,
they can grow up to about twelve inches, and not
all of them are sanguivorous. That's the term for blood suckers.
(05:07):
One of the best known leaches is called the medicinal leech,
and it has a sucker at each end of the
underside of its body. One sucker at the end contains
the animal's mouth and the other sucker acts as a
suction cup when the leach attaches itself to its victim,
and once attached this is so great. The leech slashes
its victim's skin with its sharp teeth and sucks the
(05:28):
blood and it injects the wound with a substance that
keeps blood from clotting. Really important. We'll talk about that later. Yeah,
hirodo medicinalysis, the medical leach. I also love that it's
it's it's three jaws. Now, not all leeches have three jaws.
Some have to to to jaw leeches. That's gonna make
a V shaped wound, But the three jaws make this
(05:50):
Y shaped wound for sucking. Now, you see them on
the land, you see them on an arm or something,
and they look kind of slow and wiggly, just some
sort of you know, just sting worm that can't move
around all. They much been in the water. That's where
they can really move. They use this undulating motions, wave
like like motion to propel themselves through the water. And then,
(06:10):
like you said, they attached on they feed and while
they're feeding, well basically they are two different acts that
this applies to, but feeding and mating. Once they've started
on that, you can actually cut a leech in half
and it won't notice. It'll just finish because they really
they're the laser focused on the zone, right, they're in
the zone. Yeah, And another thing is that they don't
(06:32):
just fill up with blood and as we do when
we fill up with burgers or whatever, just kind of
groan and and fall asleep. That's because the blood never
really coagulates. They've got the anti coagulating agents that is
circulating around in their body. So it's not like they
sit there and they become a lump and they just
you know, hang out for eighteen months asleep, although they
(06:53):
can subsist for eighteen months without food. But they are
quite mobile even with these really full bellies. Yeah, they
don't eat for a long time, but when they do eat,
they really go for it. They'll remain in place for
thirty minutes to six hours or more, filling up with
a blood and if they can. For instance, you can
take four or five leeches attached them to a rabbit
(07:14):
and drain the life from it in just half an hour.
That's how quick. And they can reach eleven times their
actual size, uh, their their normal size as they bloat
up on that blood. Pretty convenient right now, they have
to make every every meal count. They'll attached to skin,
but they've also been known to attach to eyeballs, uh,
orifices in the throat um. There's a there's an account
(07:38):
Napoleon's troops were marching from Egypt across the Sinai Peninsula
to Syria, and so they're they're really parched. They've come
across some water. They just fall upon it to start
drinking as much as possible. But there were leeches in it,
and so a number of the soldiers end up with
leeches in their throat. There's some swelling, there's some choking,
there's some death. Really her into stuff. All right. Well,
(07:59):
let's add to a nightmare fuel by describing one leech
species in particular which is fairly new to the roundup
of leeches. And Uh, we're talking about a leech that
goes by I don't on the street name of the
t rex leech. Yes, we're talking about Tyronto bidella rex,
the tyrant leech king. Uh. This guy reaches up to
(08:20):
forty four point five millimeters in length and goes right
for the body orifices of specifically the nose in the mouth.
Um and uh, most generally it's feeding on aquatic animals,
aquatic mammals rather uh and again go to the nose,
the mouth and then they'll name me. Stay there for
a week at a time, feasting. Yeah, this was discovered
(08:40):
in two thousand and ten, uh in the Upper Amazon,
when scientists plucked from the nose of a girl one
of these t rex is who had recently been bathing
in a river. So if that's not all just kind
of like, okay, that's that's slightly uncomfortable. And now consider
that the t rex has ferociously large teeth lining a
(09:01):
single jaw. So this is an even even different variation.
We have the three job, we have the two job,
and now this is the one job leech, but with
the teeth to make up for it. Well, and it's
it's uh, it's even more dramatic. We see pictures of
it because really we're talking about a leech that is
less than three inches long, and then you see the
teeth in comparison, and it's just kind of recoil a bit.
(09:22):
But the t retch leech uses its teeth to saw
into the tissues of mammals orifices. So again we're talking
eyes eurefas rectum's jos sawing into it with its teeth.
All right, Well, on that note, we're gonna take a break,
and when we come back, we're going to discuss the
role of the leach as the healer and uh also
look a detective. All right, Now that you've had a
(09:54):
palate cleanser with stamps dot com and we can get
away from the old t rex, let's talk about leeches
back in the day. Yeah, so leeches, they've been used
in medicine for thousands of years and the once once
believed to remove illness causing humors from the blood. So
this is based in and very uh non scientific ideas
about how the body works. I mean, some of the
(10:15):
arguably the best ideas of the time, but still ideas
that did not hold water. These are the humors of
the body. We're talking about phlegm and blood and file.
So the idea is that you let someone bleed a
bit and that helps to balance out those different humors. Yeah,
your humors are out of whack and you need to
get rid of the bad blood. So yeah, you end
up treating everything from gout to flash once to mental
(10:37):
illness with a hefty dose of leeches. Uh. It's it's
interesting that the word leech itself is derived from the
Anglo Saxon word looks to heal, and medieval doctors actually
called themselves leeches, which is interesting because I've run across
that before, and I thought maybe it was used mockingly,
you know, to say, oh, well he's just a leeches. No, no,
I think with pride, I am a leech. What can
(10:58):
I do for you today? Uh? Yeah, physicians applied lea
just to areas like the gums, lips, the nose, fingers,
and even quote the mouth of the womb, according to
a medical text from So why would they do that?
Because granted, there are a lot of crazy ideas that
have become that have had their day in history treating
using some sort of natural creature or a derivative in
(11:20):
in order to attempt to treat some sort of malady.
But in this case, we're coming down to two key
things about the leach. First of all, when a leech
attack attaches, like many parasitic organisms, it uh, it is
desensitizing the sensations, so you're not feeling the pain of
it actually uh slicing into your flesh for a meal.
But then, of course the other thing is your wound.
(11:41):
This freshly cut wound is a font from which this
leech wishes to drink and does not want that font
to close before it has had its fill. So the
leech has um an anticoagulant in its saliva as well.
That prohibits the the the coagulation of blood keeps it flowing. Okay,
So it's a end way to blood let someone because
(12:01):
they can't really feel it, and it's a way to
keep that blood flowing too. Damaged tissues, right, So it
gives a fresh supply to any sort of damaged tissues.
And here's the thing. It became so popular in the
nineteenth century that the species became endangered in Europe. In
eighteen thirty three, French doctors imported forty one million, five
hundred thousand leeches. Yeah, I was reading how in the
(12:25):
nineteenth century had governments that were imposing carraffs and trade bands.
There was a leech smuggling operation on the Russian border,
and and this was all the more difficult to because
of the time. Breeding efforts weren't all that successful, so
you just had leech catchers going out into the wild
and just harvesting them, to the point that that the
medicinal leech was in danger of extinction at one point,
(12:46):
and to this day it's it's rarity in the in
the wild is partially attributed to over harvesting. So you know,
physicians of old were sort of onto something, right, this
idea that maybe this could help in terms of bringing
fresh blood to damage tissues. On the other hand, you
have to say that the leech's ability to cure or
(13:08):
wildly overseated, so flatulence probably not cured by this. In fact,
a lot of stuff that they used it for, um,
And that's kind of what we think of today, is
that this was this barbaric use of leeches. It's like saying, oh,
I have a migraine, Well, let a wolverine chew on
your leg and you'll get over that kind of thing.
But no, that does not work. It doesn't work. But
(13:29):
at heart, that the end of the reason, like the
core reason that the leech does have a place in
modern medicine is that at heart, as a parasite, a
leech is a manipulator of human physiology, much like a
doctor in in in a very broad um scheme of things.
So if you want to manipulate the way tissues work,
(13:50):
a lot of times we're always looking to nature for examples,
for for some bio inspiration on how nature has evolved
to tackle a problem. So here's a case where this
teacher has evolved over millions of years to uh be
an expert at manipulating blood flow through tissue. And so
when a doctor, a modern doctor, needs to manipulate blood
(14:12):
flow through tissue, we turned to the leech. That's right,
and that's why they are now the comeback kid. And
now they are the symbiotic sort of parasite as as
opposed to one that's just uh one that we should
fear and that seems barbaric. In medieval medicine, Yeah, for instance,
tissue grafting and limb reattachment surgery, this is a big one.
Surgeons sometimes use the leeches to remove pools of congested
(14:35):
blood from swollen areas that interfere with the circulation and
can cause tissue death following surgery. Um. So this in
addition to the way that the the herodin the intercollegulate
prevents clotting in the local anesthetic in it that that
also features some antibiotic properties. Yeah, and this uh actually
sort of came to light more in a case in
(14:56):
nine five in which there was a harder toward physician
who was having a hard time reattaching the ear of
a five year old child. The tiny veins kept clotting,
and so it's really difficult to try to um reattach
something with these minute veins, right, so the physician thought,
maybe I'll use a leech and lo and behold he
(15:18):
did it. It helped those tiny little minute veins to
get fresh blood, and the ear was saved, and people
began to reconsider the leecher's role in medicine. Yeah. And
and as as your point out a specifically with microsurgery,
where you're dealing with these tiny blood vessels that that
are very difficult to manipulate. Yes, since then, lee just
(15:39):
have helped to save lives and limbs, reducing severe and
dangerous venous and gorgement post surgery and fingers toes, ears,
scalp reattachments, limb transplants, skin flap surgery, and breast reconstruction. Yeah.
And and there are other areas where that where researchers
are looking at possible applications. UM. For instance, uh uh.
(16:02):
Andreas Michelson, a researcher at the University of Duisburg Essen
in Germany, suggests that leech therapy may lessen the pain
and inflammation associated with osteo arthritis. Um. You know this,
of course, is a debilitating disease where the bones can
grind against one another and the cartilage is worn down
over time. So in order to get medicinal leeches for use,
(16:23):
how do you how do you go about it? Still
collect them in the backyard. Well, collecting leeches is one way,
and certainly leeches are collected, I should point out not
only for medicinal use, but also is bait and fishing.
And in order to collect leeches, I was I was
thinking maybe it involves some you know, hard on his
luck individual just taking a dive into the leechy waters
and then coming out and plucking them off. But generally
(16:44):
what it involves is like beef kidneys in a bag.
Just put beef kidneys in a bag. They go for it.
Like I said, their their their taste is rather simple.
So in a sense they're rather easy to catch. That
sounds about right, Yeah, beef kidneys in a bag that
they are then submerged into water and then the leeches come.
Then you can the bag out and you've got a
bunch of leeches, all right. So I wonder if that's
one of the techniques that bio Farm, which is a
(17:05):
company based in Britain, uses because they are the go
to source for leeches in the medical community, and they
provide tens of thousands of leeches every year to hospitals
and dozens of countries, and two species are commonly used
in leech therapy, and they can last for about up
to ten days. Okay, so they're definitely male safe. You
can send them to the mail. They're males. Now. The
(17:28):
downsides here are that sometimes they slip off patients and
they reattach themselves in unwanted places. Yeah, it's a bit
like hurting kittens in some respects. They have to just
you have to put gas around the surgical side and
just really limit where they can go and say this
is the only spot you're allowed to feed from right here.
This is the one second down side. They fill up,
(17:50):
they get full, they fall off. Yes, okay, of course
you can replace that one with another one. But for
those who just cannot even stand the idea of a
leech sucking on them, even though it might save their life. Uh.
There is Nadine Connor who is a University of Wisconsin
atmos and scientists who in two thousand and one helped
develop a mechanical leech. The device looks a little bit
(18:13):
like a small bottle attached to a section cup, and
it delivers that anti coagulating drug. Then the most important
part right to damage tissue and then gently sucks out
as much blood as needed, never drops off and says, oh,
I need a nap. So it's like all the power
of the leech, but without the having to deal with
the drama and the attitudes and the prima donna of
(18:35):
the leech. Yeah, there's no like separate dressing room. It's
just it doesn't care. This mechanical leech. Now, another advantage
of the mechanical leech is that up to twenty of
patients that are treated with real leeches developed infection caused
by aeromanus hydrophilia of bacteria that leaves and lives in
the leech is gut. And these infections are easily treated
(18:56):
with antibiotics. But again, it's another reason to ry and
remove ourselves from having to depend on a natural parasite. Indeed,
if this hasn't changed your ideas of leeches or you know,
cast it a new light of how leeches can operate
out there in the world, you have to consider this
next scenario. Uh, it's a it's a bit like Sherlock Leach, right,
(19:19):
Sherlock Leach. Yes, you can imagine the leech creeping onto
the scene of the crime and you know, wearing the hat,
smoking the pipe, playing the violin. It's not quite like that.
So about ten years ago, uh, we had this guy
named Peter Cannon and uh, this is in Tasmania. He
ties up a seventy one year old woman in a
remote home, steals several hundred dollars in cash, and uh,
(19:43):
the thing he doesn't realize that he's committing this crime
is that he has a leech attached to him. And
it is and this is luck would have it. It's
just finished feeding on him as he's perpetrating this crime
and does what a leech does when it's filled up,
It drops off and then he takes off. Right. So
this scene of the the scene of the crime. So
you can imagine the detectives coming in. They're looking around
(20:04):
and then somebody thinks to themselves, hey, there's a full
leech on the ground. I wondered that as anyway involved.
And because they all checked themselves and said, I don't
have lee, you know that the victim of the crime
doesn't have any leech bites. So where did this mysterious
leech come from? That's so that's clearly bloated on blood. Well, Uh,
the case had remained unsolved up until forensic experts extracted
(20:27):
DNA from the leeches gut contents, and then they matched
up fingerprint profiles to those on a record for Cannon.
Peter Cannon, the perpetrator here, and then he ended up
leading guilty and and they had him. Yeah. I think
this is such a great story because here's this jerk
who tied up this old lady. Thought he was being
really clever. He was probably on foot going through the bush,
(20:49):
got one of these leeches stuck to him, made off
scott free. He thinks that. Eight years later he gets
hold over. I think it's for a drug offense, right, Yeah,
he gets cross checked with that database. Bam. Detective Leech
is on the case. I wonder if they let into
it by saying, so, Mr Cannon, have you ever had
a leech attached to your body? And he's stone for
a curve, like, what what can they possibly have on me?
(21:12):
And then the leech they bring the leech in, the
leech like points at him through the class. I think
that's the one exactly what happened. I think he had
a pipe in the hat and everything. It's elementary nice,
all right. Before we leave this topic that I would
do want to mention I mentioned that that to overharvesting
of reaches leeches is one of the reasons that medicinal
leeches are rare in the natural world today. Another suspected
(21:36):
reason is that when leeches are young, they can't yet
attach to larger mammals. They have to attach to frogs.
So one theory is that as the as the frogs
become more scarce, then it's harder for young leeches to
get those first couple of meals that they need in
order to reach adulthood. So there you go. I mean,
that's another case for the circle of life and how
(21:58):
everything effects everything else, right, yeah, and uh, and that
includes the leach. So yeah, we hope that you feel
a little, uh, a little more informed about the leech
and about the use of leech, of the leech in medicine.
And certainly the next time you say watch stand by
me or just go swimming in the local watering hole,
you'll you'll reconsider that lovely creature that has perhaps attached
(22:21):
to your body if you want to learn more about
leeches and everything else that we cover, well you can
get somewhere very special. Yeah, go to stuff to Blow
your Mind dot com. That's the mothership. That's where we
have all our blog post, our videos, every podcast episode
we've ever done. And hey links out from there to
our Twitter account, our Facebook account, our tumbler account, YouTube SoundCloud.
(22:43):
You name it, uh, stuff to Blow your Mind dot com.
And Hey, if you want to get in touch with
us a more an old fashioned way, a more one
on one way, well Julie has the answer for it.
That's right. If you want to tell us in detail
about your own leech stories, especially Robert, I know he
wants a lot of detail on to attaching to your mind. Um,
you can describe it and then send it to blow
(23:05):
the mind at discovery dot com for more on this
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