All about Leeches (2)

Medicinal Leech

Reproduction

Leeches are hermaphrodites, meaning each one of them has both female and male reproductive organs (ovaries and testes respectively). Leeches reproduce by reciprocal fertilization, and sperm transfer occurs during copulation. The leech exercising the role of the male will grow a sperm sack near the end of its tail, and the leech playing the female will bite it off, thus reproducing. Similarly to the earthworms, leeches also use a clitellum to hold their eggs and secrete the cocoon.

During reproduction leeches utilize hyperdermic injection of their sperm. They use a spermatophore, which is a structure containing the sperm. Once next to another leech, the two will line up with their anterior side opposite the other's posterior. The leech then shoots the spermatophore into the clitellur region of the opposing leech where its sperm will make its way to the female reproductive parts.

Leeches and a History of Medicine

For over 4000 years, the leech has been a familiar remedy, with Greek and Roman physicians praising the application of this clever invertebrate.

In the 19th century leeches were enjoying a golden age. Millions were raised for medical use as their fame as a cure-all ensued. The mid 1800s saw their constant use for local bloodletting. Druggists administered thousands of leeches to patients with anything from gumboils to facial discoloration.

Leeches were applied to the mouth and inside of the throat using a leech-glass, although patients frequently swallowed them. Patients were relieved only with a salty drink of water or perhaps the most popular cure-all of the day, a couple of glasses of wine. Sometimes the leech would not drink and then had to be encouraged by some blood or cream smeared at the puncture site or bathed in a warm glass of beer until ready.

Once sucking, an average leech would drink blood weighing as much as itself in about 15 minutes and consume between 2.5-5.5 grams of blood (half a teaspoon). If the bite failed to stop bleeding after the leech was removed then vinegar, silver nitrate and hot wires were applied.

Apart from using the English and Scottish leeches, huge numbers were imported from France, Hungary, the Ukraine, Turkey, Romania, Russia, Egypt and Algeria. In 1846 in France alone, 30 million leeches were used. Hospitals in both London and Paris required 13 million between them for that single year. America produced their own leeches and one farm sold over a thousand per day.

Leeches were also caught from the wild by many interesting ways, including men bathing a muddy ditch or in a stream with a glass of pig blood, rolling their trousers up and wading into the water. Here they would wait patiently for leeches to adhere themselves to their legs. After a while, back on land the feeding leeches would be stripped off and sold to leech dealers. The leech industry began its decline due to the over collection of the animal and its discredit by the medical profession. By the end of the 19th century the golden age of the leech had passed.

Today leeches are bred in captivity in many institutions including Bristol Zoo Gardens. Leeches have found new fame in microsurgery, where doctors require the precision of the leech to drain congested blood from wounded sites. Plastic surgeons are particularly grateful for the contribution made by the leech, due to their use in the treatment of difficult grafts and reconstructive surgery.

In the past

In medieval and early modern medicine, the medicinal leech (Hirudo medicinalis and its congeners Hirudo verbana, Hirudo troctina and Hirudo orientalis) was used to remove blood from a patient as part of a process to "balance" the "humors" that, according to Galen, must be kept in balance in order for the human body to function properly. (The four humors of ancient medical philosophy were blood, phlegm, black bile, and yellow bile.) Any sickness that caused the subject's skin to become red (e.g. fever and inflammation), so the theory went, must have arisen from too much blood in the body. Similarly, any person whose behavior was strident and "sanguine" was thought to be suffering from an excess of blood.

The first recorded use of leeches in medicine was in 200 BC by the Greek physician Nicander in Colophon. Hirudotherapy, the use of medicinal leech for medical purposes, was later popularised by Avicenna in The Canon of Medicine (1020s). He considered the application of leech to be more useful than cupping in "letting off the blood from deeper parts of the body." He also introduced the use of leech as treatment for skin disease. Leech therapy became a popular method in medieval Europe, namely the leeches from Portugal and France, due to the influence of his Canon.

A more modern use for medicinal leech was introduced by Abd-el-latif al-Baghdadi in the 12th century, who wrote that leech could be used for cleaning the tissues after surgical operations. He did, however, understand that there is a risk over using leech, and advised patients that leech need to be cleaned before being used and that the dirt or dust "clinging to a leech should be wiped off" before application. He further writes that after the leech has sucked out the blood, salt should be "sprinkled on the affected part of the human body. The use of leeches began to become less widespread towards the end of the 19th century.

Today

Medicinal leeches are now making a comeback in microsurgery. They provide an effective means to reduce blood coagulation, relieve venous pressure from pooling blood (venous insufficiency), and in reconstructive surgery to stimulate circulation in reattachment operations for organs with critical blood flow, such as eye lids, fingers, and ears. The therapeutic effect is not from the blood taken in the meal, but from the continued and steady bleeding from the wound left after the leech has detached. The most common complication from leech treatment is prolonged bleeding, which can easily be treated, although allergic reactions and bacterial infections may also occur.

Because of the minuscule amounts of hirudin present in leeches, it is impractical to harvest the substance for widespread medical use. Hirudin (and related substances) is synthesized using recombinant techniques. Devices called "mechanical leeches" have been developed which dispense heparin and perform the same function as medicinal leeches, but they are not yet commercially available.

Hirudo medicinal

The medicinal leech and the leech therapy are thousands of years old well known medical treatment. The medicinal leech is assigned with problem definitions such as cramp veins, vein diseases and arthritis or tinnitus. One already finds the first recordings over the use of the medicinal leech for the leech therapy in the 2ten century before Christi from the Greek Nikander von Kolophon, who used the leech and the leech therapy particularly for the treatment of poisoned snake bites.

In the modern medicine the medicinal leech and the leech therapy experiences nowadays again renaissance in its use for different diseases.

Apart from the classical areas for the medicinal leech for the leech therapy such as cramp veins, vein diseases, arthritis, tinnitus today the leech therapy is used also in the modern reconstructive and plastic surgery. Here the medicinal leech helps to improve a venous congestion in case of e.g. reimplanting a lost finger through an accident.

The leech therapy

The leech therapy should be accomplished only by experienced Therapists!

How many leeches do I need for a therapy.

The necessary number of leeches depends by the following factors: Age and weight of the patient, the kind of disease and the size of the leeches available.

The leech sucks approx. 30 minutes. One should let the animals in peace suck and under no circumstances when sucking disturb. Likewise should not be under any circumstances smoked in the environment. Sucking should not be artificially interrupted. At the end of sucking the leech of alone drops. Sometimes it happens that the animals suck after that is so slow-acting that they remain hanging on the patient. Into such to fall it helps to drive with a putty under the front suction cup and take so the leech off. Please you make sure however that them the leech thereby not crimping around vomiting the leeches, and thus a possible infection to prevent. For this reason also no salt may be used for removing the leeches.

When chronic illnesses one sets fewer animals for it the therapy however in shorter time intervals is on repeated. With acute diseases one uses more leech and has a longer period up to the next treatment. For a normal adult with standard weight and no further medical treatment and in a healthy condition 10 leeches may be use for a therapy.