What Would Happen If You Swallowed a Leech?

This isn't just the least-fun thought experiment, it's a medical malady common enough to have its own name. Learn how internal hirudiniasis works (and why you don't need to panic if if happens to you) in this episode of BrainStuff, based on this article: https://animals.howstuffworks.com/marine-life/swallow-leech.htm

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Episode Transcript

Speaker 1 (00:01):
Welcome to Brainstuff, a production of iHeartRadio. Hey Brainstuff, Lauren Vogelbaum.
Here just a heads up, this episode gets a little gross.
In case you didn't see the title or description before
it started, It's about leeches and what would happen if
you swallowed one. If that's not what you're into hearing

(00:22):
about today, go on and skip it. Okay, okay. So.
In eighteen ninety five, one surgeon, Lieutenant Ta Granger of
the British Indian Army wrote a letter to the British
Medical Journal to report a stomach turning case of parasitic
infestation that he encountered at his colonial outpost. While working

(00:43):
at a fort in the Northwest Provinces of India, Granger
received a letter from an officer asking for his help
with an unusual medical complaint. According to the note, a
local man had a leech attached to the inside of
his throat. At first, Granger assumed it couldn't be true,
but he agreed to see the patient. By Granger's account,

(01:04):
the patient was an elderly man with a gray beard, who,
when Granger came within sight, immediately spat out a heavy
mouthful of thick, blackened blood. As though to demonstrate that
his complaint was real. With the help of interpreters, Granger
asked the man about his condition. He revealed that eleven
days previous, he had been drinking out of a rainwater

(01:25):
tank when he suddenly felt something catch in his throat.
When he tried to cough it up, he couldn't. Then
the thing caught in his throat began to move. He
had difficulties swallowing and felt like he was going to
choke on the writhing obstruction, and it caused him to
vomit and spit up blood repeatedly. When Granger first looked

(01:46):
inside the old man's throat, he was able to remove
a clot of blood, but couldn't see any parasites. If
it was there, it had to be deeper, so the
surgeon lieutenant produced a pair of polypus forceps, essentially very
long tweezers with scissor handles, and reached into the hidden
depths of the man's lower pharynx near the esophagus. There,

(02:08):
through the instrument, Grainger detected the presence of an object
and could feel it moving. With the tips of the forceps,
he grasped the squirming obstruction and with considerable force pulled
it out. Indeed, it was a leech some two and
a half inches long that's around six and a half centimeters,
with a body shaped like the bullets of the British

(02:30):
infantry used in their lee Metford rifles. This slimy, writhing
rifle cartridge, engorged with human blood, had been living in
the man's pharynx for eleven days. Granger's letter to the
British Medical Journal does not go on to report what
happened to the old man, but after an experience like this,
one would hope that the worst was already behind him.

(02:54):
When it comes to leeches in the throat, Grainger's report
is not an isolated incident. Granger himself reported hearing stories
of other cases like this in neighboring towns, and the
phenomenon is by no means limited to nineteenth century India.
Getting a leech attached to the inside of a body
cavity is common enough that there are special medicalized terminologies

(03:17):
for it, such as leech and no parasitism or internal
here udoniasis. These are phrases that most of us would
probably rather not have in our vocabulary, but even today,
in the twenty first century, people still show up at
hospitals around the world with leeches stuck inside their throats.
Strictly speaking, the leech is a type of worm phylum

(03:39):
Anellida subclass here Udinia, from which we get the aforementioned
word here youdeniasis, which is the condition of being parasitized
by a leech. The leeches have squishy, segmented bodies imagine
rings like on an earthworm, and they have suckers at
both ends, one large sucker at the rear of the
body used for crawling and leverage, and a smaller sucker

(04:03):
at the front containing the jaws and mouth. Not all
leeches drink blood, Some scavenge for detritis, and some are
predatory hunters. But the leech we know best is the
type of parasite that clamps onto a larger host and
steadily drains all the blood it can, often until the
leech's body has swollen to around ten times its original size.

(04:26):
In the wild, leeches drink from all manner of hosts,
such as mammals, fish, and amphibians. When the leech bites,
it makes a wide shaped incision in the skin with
three curved jaws covered in serrated teeth like tiny circular
saws and then extracts blood with a muscular sucking action.
The saliva of the leech is known to contain a

(04:48):
cocktail of drugs to ease the process, including her youdin,
a polypeptide that prevents blood from clotting. It was first
isolated in and thus named after leeches. Leeches are classically
known as external parasites, drawing their liquid diet through the
outer skin of the host, but given the opportunity, they'll

(05:08):
feed from internal surfaces too, basically any that they can reach.
Humans have an unusual relationship with leeches that's perhaps unique
among all the world's parasites. The use of leeches is
pervasive throughout the history of medicine. In some historical periods
they were so commonly used as instruments of bloodletting. The

(05:30):
collecting wild leeches was a solid money making operation, and
although it might eke us out today, the human taste
for therapeutic parasitism did not stop at the outer skin.
During the leech craze, leeching enthusiasts opened many of their
bodily orifices and internal cavities to these prized worms, and

(05:52):
with the help of varying medical technology. In an article
on the technological history of leeching published in twenty eleven
in the journal Medical History, the authors wrote the opening
of the interior of the body often required the physical
alteration of the leech, for example, the attachment of thread
to prevent the loss of the leech within, or the

(06:12):
supplementation of the leech with mechanical tools to enable the
passage of the creature into locations such as the anus,
where it was recommended as a means to treat problematic prostates.
There are even a few limited ways in which leeches
have proven useful, though perhaps still controversial, in the science
based medicine of recent decades, such as to ensure that

(06:35):
veins are working properly and aren't overfilling or distending after microsurgery.
Leech infestations of the throat are rare these days, especially
in developed countries with easy access to clean water, but
it can still happen. Possible symptoms of a leech in
the throat are difficulty swallowing, sore throat, coughing up or

(06:56):
vomiting blood, a sense of having a foreign body in
the throat, molina, which is the term for dark, sticky
feces indicating the swallowing of blood, a feeling of suffocation
or shortness of breath, and or harsh or raspy breathing.
If you think that you've got a leech in your
throat right now, don't panic. Just see a doctor as

(07:17):
soon as you can. With modern imaging and local anesthesia,
the ordeal will likely be more awkward and sort of
gnarally than anything else, though it can be dangerous if
the parasite obstructs any part of the airway. If the
doctor knows what to look for and has a pair
of blunt forceps on hand, chances are good that you'll
be just fine. But of course the best case scenario

(07:40):
is to avoid the problem entirely, which these cases seem
to indicate. You can do by drinking only from clean
water sources or filtering and purifying all the water you use,
and also by avoiding swimming in any water that might
be infested with leeches. Today's episode is based on the

(08:03):
article Here's what Happens when you swallow a leech on
HowStuffWorks dot com, written by Joe McCormick. If after that
you want to hear more from Joe, you can find
him on the podcast Stuff to Blow Your Mind. Brain
Stuff is production of iHeartRadio in partnership with how stuffworks
dot com, and it is produced by Tyler klang A.
Four more podcasts from iHeartRadio. Visit the iHeartRadio app, Apple Podcasts,

(08:24):
or wherever you listen to your favorite shows.