What Happens When You Swallow a Leech?

Although cases are rare, a non-zero number of patients have gone to doctors with a leech stuck in their throat over the years. In this special episode, we explore this gross but fascinating circumstance. Music by Eric Matyas www.soundimage.org

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Episode Transcript

Speaker 1 (00:01):
Welcome to How Stuff Works. Now. I'm your host, Lauren Vogelbaum,
a researcher and writer. Here's how Stuff Works. Every week
I'm bringing you three stories from our team about the
weird and wondrous advances we've seen in science, technology, and culture,
except when I don't. This week, we've got just one
story for you, but it's a longer one, so don't worry.

(00:23):
If you're driving, you've still got about the same amount
of time before you have to fiddle with your phone again.
This one is from staff writer and editor Joe McCormick,
who's also the co host of a compatriot podcast of ours,
Stuff to Blow Your Mind. Joe wanted to know how
and what happens when a human swallows a leech, which
is a thing that happens more often than you'd like

(00:43):
to thank, which, to be fair, is more often than never.
So come along as Joe explores the historical and modern
cases of leech endo parasitism. Here's what happens when you
swallow a leech. In surgeon Lieutenant T. A. Granger of

(01:06):
the British Indian Army wrote a letter to the British
Medical Journal to report a stomach turning case of parasite
infestation he encountered at his colonial outpost. While working at

(01:29):
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. Nevertheless, he
agreed to see the patient. The person he encountered was,

(01:52):
by Granger's account, an elderly pashtooned man with a gray beard.
When Granger came within sight, the old man immediately spat
out a heavy mouthful of thick, blackened blood, presumably to
demonstrate that his complaint was real. With the help of interpreters,
Granger questioned the man to learn about his condition. According

(02:12):
to his story, eleven days previous, the old man had
been drinking out of a rainwater 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 difficulty swallowing and
felt like he was going to choke on the writhing
obstruction it caused him to vomit and to spit up

(02:35):
blood repeatedly. When Granger first looked inside the old man's throat,
he was able to remove a clot of blood, but
couldn't see any parasite. 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 farynx,

(02:58):
near the esophagus they are. He detected the presence of
an object, and through the metal of his instrument, Granger
could feel it moving. With the tips of the four steps,
he grabbed hold of the squirming object and with considerable force,
pulled it out. Indeed, it was a leech between two

(03:19):
point five and three inches or about six and a
half to seven and a half centimeters long, with a
body shaped like the three oh three inch ammunition the
British infantry used in their lee Metford rifles. A slimy,
writhing rifle cartridge engorged with human blood had been living
in this man's throat for eleven days. Granger's letter to

(03:42):
the b MJ doesn't go on to report what happened
to the old man, But after an experience like this,
one would at least hope the worst moment in the
man's life was behind him. When it comes to leeches
in the throat, Granger's report is not an isolated incident.
Granger himself heard stories of other cases like this in

(04:03):
neighboring towns, and this 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 for it, such as leech indo
parasitism or internal hierodoniasis. These are phrases most of us
would probably rather not have in our vocabulary, but even today,

(04:26):
in the twenty first century, people still show up at
hospitals around the world with leeches stuck inside their throats.
Strictly speaking, the leeches a worm phylum Analyta subclass heroudonea,
from which we get the word hierudoniasis, which refers to

(04:47):
the condition of being parasitized by a leech. Leeches have
segmented bodies imagine rings like an earthworm, and suckers at
both ends. One large sucker at the rear of the
body used crawling and leverage, and a smaller sucker at
the front containing the jaws and the mouth. Not all
leeches are blood drinkers. Some scavenge for detritus, some are

(05:10):
predatory hunters. But the leech we know best is that
vampiric parasite that clamps onto the larger host and steadily
drains all the blood it can, often until the leech's
body is swollen to around ten times its original size.
In the wild, leeches drink from all manner of hosts, mammals, fish,
and amphibians. When a leech bites, it makes a y

(05:32):
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 cocktail of chemicals to
ease the process, including heroudin, a polypeptide that prevents blood
from clotting. Leeches are classically known as external parasites, drawing

(05:55):
their liquid diet through the outer skin of the host,
but given the ratunity, they will feed from internal surfaces
as well, such as the nave of pharynx, larynx, vagina, bladder,
and anus. 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, even giving

(06:19):
the European medical leech harudo medicine alis its modern name.
In some historical periods, they were so commonly used as
instruments of blood letting that collecting wild leeches was a
solid money making operation. Rural leech gatherers would wage bare
legged through the scum of stagnant ponds, hoping when they

(06:40):
emerged on the other side to see patterns of glistening
green black anelids sucking from their ankles and calves. In
his eighteen oh seven poem Resolution and Independence, the English
romantic poet William Wordsworth writes about his encounter with this
brand of leech harvester quote. He told that to these
waters he had come to gather leeches, being old and poor,

(07:02):
employment hazardous and wearisome, and he had many hardships to endure.
From pond to pond, he roamed from more to more,
housing with God's good help by choice or chance, And
in this way he gained an honest maintenance. Assuming you
find the idea of being sucked by a leech somewhat disgusting,

(07:23):
and assuming you find the idea of being sucked by
a leech on the inside of your body even more disgusting,
you might find it odd that the human taste for
therapeutic parasitism doesn't stop at the outer skin. During the
leech craze, leaching enthusiasts open many of their bodily orifices
and internal cavities to the prized worms with the help

(07:43):
of some ingenious medical technology. In a two thousand eleven
article on the technological history of leeching, Robert G. W.
Kirk and Neil Pemberton right that quote. 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 supplementation

(08:05):
of the leech with mechanical tools to enable the passage
of the creature into locations such as the anus, where
it was now 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 veins

(08:25):
are working properly and aren't overfilled or distending after microsurgery.
Here and there, you can still encounter reports in medical
journals of rare cases of accidental internal hyerdoniasis, including leeches
in the throat. In two thousand two, a group of
doctors reported in the journal Pediatric Pulmonology the case of

(08:47):
a six year old boy in Syria who was brought
to the emergency room because he couldn't breathe. His mother
reported that he had been coughing up blood and that
a month ago a village doctor had diagnosed the boy
with asthma and prescribed court steroids and broncho dilators. This
turned out to be a misdiagnosis. The doctors were able

(09:07):
to remove a seven centimeter or nearly three inch leach
from the boy's airway through surgery, and subsequently discovered that
the child had been drinking from a leech infested stream
in rural northern Syria. After the leech was removed, the
boy's symptoms disappeared. In two thousand nine, another group reported
in the European Journal of Pediatrics the case of an

(09:28):
eleven year old boy in central Iran who presented it
a rural healthcare center with blood in his mouth and
a sore throat that had lasted for two weeks. The
boy had been given antibiotics for his sore throat and
the problem did not respond. Inspection of his mouth revealed
a black circular blob about two centimeters by three centimeters
or about point eight by one point two inches, stuck

(09:51):
to the back of his throat, with blood oozing all
around it. Doctors applied litacaine spray, a topical pain killer,
and then pull the leech out with blunt forceps. Questioning
revealed the boy had been swimming in a lake near
his village. After the leech was removed, blood continued to
ooze out of the wound for about an hour, but
otherwise the boy was all right. In a doctor named

(10:14):
Demeckey McConnon published an article in the Ethiopian Journal of
Health Science relaying the case of a seven year old
boy in Ethiopia who presented with blood stained saliva and
shortness of breath at his home. Someone had tried to
treat him with a traditional medicine made of tobacco leaves
and flax seed to no effect. In the report, McConnon
indicates that the boy had contact with an unprotected source

(10:37):
of spring water that was also used for watering animals.
Luring scopy showed some kind of foreign body at the
top of the trachea. The child was put under general
anesthesia and the leech was removed with forceps. After the extraction,
the boy seemed to have a full recovery. Laryngeal and
pharyngeal leech infestations are rare these days, especially in developed

(11:00):
countries with access to clean water, but it can still happen.
Possible symptoms of a leech in the throat are difficulty swallowing,
sore throat, vomiting blood, coughing up blood, a sense of
having a foreign body in the throat melna meaning dark
sticky feces indicating the swallowing of blood, a feeling of

(11:20):
suffocation or shortness of breath, and harsh or raspy breathing.
If you think you've got a leech in your throat
right now, don't panic. Just see a doctor as soon
as you can, as you may have gathered from the
cases we just mentioned, pharyngeal or even laryngeal harrod niasis
is not necessarily a death sentence, though it can be
dangerous if the parasite obstructs any part of the airway.

(11:42):
If the doctor knows what to look for and has
a pair of blunt forceteps on hand, chances are good
that you'll be all right. But of course the best
case scenario is to avoid the problem entirely, So don't
drink dirty water and don't swim in the water where
the leeches slim. That's our show for this week. Thank
you so much for tuning in. Further thanks to our

(12:03):
audio producer Dylan Fagin and our editorial liaison Alison Laddermilk.
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