Bugs and parasites are making a comeback into modern medicine, and
although they have been used as a means of therapy for thousands of
years, they lost their popularity in the second half of the 20th century
only to regain their previous status as medical wonders during the
1980s. Two such parasites used today are leeches and maggots. As
gruesome as both are conceived, they have been found to possess numerous
advantages in the field of medicine.
The Practice of Leeching Throughout History
The use of leeches in medicine dates as far back as 2,500 years ago
when they were used for bloodletting in ancient Egypt. All ancient
civilizations practiced bloodletting including Indian and Greek
civilizations. In ancient Greek history, bloodletting was practiced
according to the humoral theory, which proposed that when the four
humors, blood, phlegm, black and yellow bile in the human body were in
balance, good health was guaranteed. An unbalance in the proportions of
these humors was believed to be the cause of ill health. Records of this
theory were found in the Greek philosopher Hippocrates’ collection in
the fifth century B.C. Bloodletting using leeches was one method used by
physicians to balance the humors and to rid the body of the plethora.
In medieval Europe, a number of superstitious ideas and religious
philosophies started to influence the practice of bloodletting. The
practice continued on up until the 19th century. In 1833, bloodletting
became so popular in Europe, that the commercial trade in leeches became
a major industry. France, suffering a deficiency, had to import 41.5
million leeches. The medicinal leech almost became extinct in Europe due
to the extremely high demand for them. Leeches were collected in a
particularly creepy way. Leech collectors would wade in leech infested
waters allowing the leeches to attach themselves to the collector’s
legs. In this way as many as 2,500 leeches could be gathered per day.
When the numbers became insufficient, the French and Germans started the
practice of leech farming. Elderly horses were used as leech feed where
they would be sent into the water and would later die of blood loss.
Leeches were thought to be able to cure everything from headaches to
brain congestion. They were used to cure obesity, hemorrhoids,
nephritis, laryngitis, eye disorders as well as mental illness. Their
use continued on until the 1960s when their use in medicine was
discontinued.
Leeches in Modern Medicine
The
use of leeches in medicine, otherwise known as Hirudotherapy, made its
comeback in the 1980s after years of decline, with the advent of
microsurgery such as plastic and reconstructive surgeries. In operations
such as these, one of the biggest problems that arises is venous
congestion due to inefficient venous drainage. This condition is known
as venous insufficiency. If this congestion is not cleared up quickly,
the blood will clot and arteries that bring the tissues their necessary
nourishment will become plugged and the tissues will die. It is here
where the leeches come in handy. After being applied to the required
site, they suck the excess blood, reducing the swelling in the tissues
and promoting healing by allowing fresh, oxygenated blood to reach the
area until normal circulation can be restored. The leeches also secrete
an anticoagulant (known as hirudin) that prevents the clotting of the
blood.
The leech’s saliva is truly extraordinary containing a number of
chemical compounds useful in medicine. These include a local anesthetic
that the leech uses to avoid detection by the host, the anti-coagulant
hirudin that can help prevent heart attacks and strokes, a vasodilator
and a prostaglandin that help reduce swelling. The leech’s gut harbors a
bacterium known as
Aeromonan hydrophila. This bacterium aids
in the digestion of ingested blood and produces an antibiotic that kills
other bacteria that may cause putrefaction.
Not only are leeches economically beneficial costing as little as
$4.75 to $6.50 apiece, but studies have shown that Hirudotherapy doubles
the success rate of transplanted tissue flaps. This is a much higher
success rate than that brought on by drugs or further surgery.
Hirudotherapy has proven to be useful for a number of other
conditions including cardiovascular disease, ophthalmology and
dermatology. Hirudin is also used in the treatment of inflammation of
the middle ear. Osteoarthritis, which is a painful condition of the
knee, is also thought to benefit from leeching. Studies performed by
researchers from the Essen-Mitte Clinic in Germany have shown that when
leeches were applied to the knees of patients with osteoarthritis, they
helped to alleviate the inflammation and pain associated with the
condition.
The hazards associated with leech therapy include infection, excess
blood loss that may require blood transfusion, the loss of leeches in
body orifices and spaces, and allergic reactions. Some patients find the
use of leeches disgusting, which makes it necessary that they have
basic information on the benefit of leeches before the procedure. The
secretion of a local anesthetic by the leech makes the procedure
painless except for the initial attachment phase. They fall off promptly
after they have completed feeding.
Scientists at the University of Wisconsin-Madison have developed a
mechanical leech as an alternative to real leeches. The synthetic leech
mimics the action of the leech allowing for fresh blood to flow through
the wound, but unlike the leech, it is insatiable and can continue to
remove blood for as long as is needed whereas the leech only feeds for
about half an hour.
Maggots a Good Thing?
Maggots are now once again gaining respect in the medical field.
Their use even has a name, maggot debridement therapy or MDT. Maggots
are efficient healers of wounds. This was recognized centuries ago when
wounded soldiers whose wounds were infested with maggots healed better
than those that were not infested. The reason for this is that the
maggots used for this purpose eat dead tissues and leave the healthy,
living tissues alone. They also excrete substances which inhibit and may
even kill bacteria. This is especially useful in areas with poor blood
supply that do not benefit much from antibiotics that cannot reach the
area in adequate concentration to do their job.
Maggots have been known for their healing ability since the 16th
century. Maggot therapy continued until the 1930s when their use in
therapy was so common that over 300 hospitals in the US alone were using
them. In the 1940s antibiotic therapy and surgical techniques replaced
the use of maggots. Their superiority in certain cases to antibiotics
was realized in 1989 when they were recognized to be more efficient
cleaners of wounds than any other non-surgical treatment.
Not
all maggots can be used in medicine; only those that do not burrow
under the patient’s skin and do not eat healthy tissues can be used.
They do not multiply in the wound as they must leave it to pupate or
they will die. When the maggots have completed their job, the doctor
simply flushes them out of the wound. The maggots range from 1 to 2 mm
in length when they are one day old and they reach a length of about 1
cm by their fourth day.
In order to ensure their sterility, scientists have developed
techniques to farm maggots for medical use. The cost of maggot therapy
is typically half as much as conventional therapy making it a very cost
effective procedure. The only disadvantage of this type of therapy other
than the yuck factor is the tickling sensation felt by some patients.
http://www.scienceinafrica.co.za/2003/july/leech.htm
