July 5, 2004
Leeches are parasites.
organism that grows, feeds, and is sheltered on or in a different
organism while contributing nothing to the survival of its host."
While the leeches you
find in the creek behind your house may be parasites, researches
have discovered that some, in more controlled environment,s can
be used to improve the health of the host.
"February 1, 1995
Using Leeches as Bait to Go Fishing for New Anticlotting Drugs...
When you cut yourself, you need to clot so that you don't bleed
to death. However, sometimes too much clotting leads to serious
trouble. For instance, heart attacks are caused by blood clots
in the heart and strokes are caused by blood clots in the brain.
Triggering clotting in humans is very complex, making sure our
blood clots when it should, but not when it shouldn't.... The
blood sucking creatures such as leeches, ticks, vampire bats,
mosquitoes, snakes, and others have successfully adapted to feeding
on mammals by shutting down the clotting process of the 'victim.'...Perhaps
the best understood of all the bloodsucking animals is the leech...."
Using leeches to help
the sick is nothing new.
"Since the Golden
Age of Greece, leeches have been famed for their bloodsucking
ability. In fact, during the middle ages of Europe through the
early to mid-nineteen hundreds, they were used for medicinal purposes.
Today, though it is rare, they are still used to reduce blood
volume or control bleeding in some patients....The American medicinal
leech, Macrobdella decora, has been found in several farm
ponds in Kentucky. This leech has a large, round mouth that also
functions as a sucker to hold on to the host. Jaws around the
mouth opening hold many fine, conical teeth. Wounds produced when
bloodsucking leeches attach to humans or livestock will bleed
for a while after the leech is removed or drops. An enzyme secreted
by the leech keeps blood from coagulating as it feeds."
Though the practice of
using leeches has been around for centuries, their uses are far
more specific--and more understood--today, in 2004.
"The leech was indispensable
in 19th Century medicine for bloodletting, a practice believed
to be a cure for anything from headaches to gout. Leeching was
largely abandoned as medical science advanced, only occasionally
being called upon to treat bruising and black eyes. However, the
medicinal leech is making a comeback in modern medicine...The
rationale behind the use of leeches in surgical procedures is
fairly straightforward; nonetheless, it is subject to misunderstanding,
even by clinicians. The key to success is the exploitation of
a unique property of the leech bite, namely, the creation of a
puncture wound that bleeds literally for hours. The leech's saliva
contains substances that anaesthetise the wound area, dilate the
blood vessels to increase blood flow, and prevent the blood from
Just last month:
-- The government has lent its seal of approval to a marketing
an age-old medical device -- leeches. The Food and Drug Administration
said Monday that Ricarimpex SAS, a French firm, is the first company
to request and receive FDA clearance to market the bloodsucking
aquatic animals as medical devices. Leeches are already widely
used in American hospitals...FDA reports that leeches can help
heal skin grafts by removing blood pooled under the graft and
restore blood circulation in blocked veins by removing pooled
blood....In considering the Ricarimpex application, FDA said it
analyzed the use of leeches in medicine, evaluated safety data
provided by the
firm and studied how the leeches are fed, their environment and
the personnel who handle them."
Leeches are still parasites,
and those you find in the wild should still be treated as such.
Leeches have been approved as medical devices to be used by doctors.
They would fall into the category of: Don't try this at home.
have found many medicinal applications and uses for leeches, they
can be a nuisance. In 1799, soldiers serving under Napoleon marched
from Egypt across the Sinai Peninsula to Syria. They drank water
from any source they could find, including waters contaminated
by leeches. As a result many problems occurred when the leeches
attached to the insides of the soldiers noses, mouths, and throats.
Once attached, the leeches began to gorge on blood and enlarge.
Many of the soldiers died from suffocation due to the enlarged
leeches in the air passages. In addition, other soldiers died
from excessive blood loss."
The same qualities that
make leeches bothersome parasites also make them useful to the
Questions of the Week:
In what ways can scientists and doctors turn negative side effects
for some into positive results for others? What have we learned
by observing the characteristics of leeches? What characteristics
naturally found in other organisms are scientists hoping to reproduce
to benefit humans? What characteristics have you observed that
you think they should be researching--if they are not already?
Please email me with any ideas or suggestions.
Note: Due to increasing amounts of SPAM sent to this account, please include "QOW" in the subject line when sending me email.
I look forward to reading
what you have to say.
Health Community Coordinator
Access Excellence @ the National Health Museum