Here’s
a newsflash: Leeches are making a comeback!
Yes,
it’s true. Our little bloodsucking friend, banished from modern medicine for
almost a century, has made a resurgence within the medical community. That
age-old practice of leeching has swung back en vogue and its contribution to
patient care and disease prevention is on the rise. So let’s take a closer look
at these little suckers (sorry, I couldn’t resist).
At
what point in our evolutionary history did our bloodsucking buddy make its
first appearance?
It
turns out leeches evolved from harmless freshwater worms, as evidenced from
their DNA, as well as certain physical traits they share. They, like their
wormy relatives, sport a sucker at the base of their tails that enables them to
trundle along, inchworm fashion, as they make their way across the landscape
or traverse potential hosts.
There
are between seven hundred and one thousand species of leeches on the planet. The one most
commonly used in medicine is aptly named Hirudo medicinalis.. Many leeches
live in water environments, both marine and estuarine, where they latch onto
fish, thereby securing dinner as well as transportation. Those that scoot about
on land prefer moist environments and are masters at camouflage, blending in
with their surroundings as they search out their next meal. Not all of them feed on
blood. Some prefer insects, mollusks, and even their humble cousin, the earthworm.
Some are happy simply munching on surrounding ground litter. The bloodsuckers
give them all a bad name.
I
know what you’re wondering… how do leeches make more leeches? It turns out
leech sex is quite exotic. Many species are hermaphroditic, meaning they
possess both male and female reproductive organs. Their procreative inventory includes several
pairs of testes, one pair of ovaries, and, for those that engage in sex, a single
orifice through which all the action takes place. They cuddle up to each other,
either face to face or face to tail (who would have guessed they know about the
“69” position?), and some don’t cuddle at all; they simply deposit their sperm
on their partner, which then dissolves a small portion of skin, allowing the
sperm to enter the mate’s body. Once inside, the sperm migrate to the ovaries,
where they perform their magic.
So
what do these little dudes have to do with the human body? A lot, it turns out,
for they possess special gifts that only leeches can bestow upon needy patients.
Their
application in medicine goes back over four thousand years, but they enjoyed their
heyday in the 1st century and were employed for a range of issues, from fevers to farting. Galen, one of the earliest physicians, promoted the use
of leeches to restore the “humors” of the body.
Practitioners
achieved this through bloodletting: a technique of “bleeding” a patient to
remove illness or impurities from the body. The leeches would be applied and
would go to town on their host. And as it turns out, they’re quite efficient. A
leech can consume its weight in blood in a mere fifteen minutes! Pretty
impressive. If given the time and an accommodating host, leeches can consume up
to eight times their own body weight, and when full, they simply detach from
their host and roll off.
The
use of leeches was such a booming industry in France that over forty million were
imported during the late 1800s. In fact, recently a French company was the
first to request and receive FDA approval to market leeches for medicinal use. Let’s
face it, the French are simply enamored of the leech.
Thanks
to a dedicated cadre of leech scientists, we now know more about their
physiology and their potential application in modern medicine. It turns out
leech saliva has magical properties. It contains natural anesthetics that help
dull pain at the site of attachment, which comes in handy, for leeches are now
being utilized to drain blood from swollen appendages following trauma and
surgery. Leech saliva also dilates blood vessels, thus increasing blood flow to
the site, which promotes healing. And finally, leech spit contains hirudin, which inhibits blood from clotting. This anticlotting property is now advancing
the use of leeches on patients receiving grafts and reattached appendages.
For example, say
you’re slicing your morning bagel and accidentally lop off a finger. Once you
arrive at the hospital and are whisked to surgery, the doctor reattaches the
digit and you’re wheeled into the recovery room. When you wake up, you look
down to find a couple of chubby leeches happily affixed to your wounded
hand. You watch as their bodies engorge to near-bursting before they detach and
roll off.
Don’t
panic! These guys are doing what they do best. By applying leeches to newly
grafted body parts, the leech’s saliva keeps blood flowing to the area, thus
promoting the growth of new vessels and enhancing circulation.
So
let’s give the leech a little respect. It just goes to show that we can find a
true friend and ally among even our most humble relatives.
And
now, for your viewing pleasure, witness LEECHES IN ACTION (click here)!!
