Dr. Anand B. Barve
Sus`hruta defines the leech as Jalaukaa and the name arises from the misconception that they are specifically aquatic organisms. Our misconceptions about leech start here and go on and on. The process of blood letting is called as Phlebotomy. Its medicinal application was well known by Ayurveda and it is described in a much scientific way. Among four types of bloodletting described in Ayurveda; three are mechanical and only one the leech is the natural device. As it is a live device; its mechanism of action is much more complicated than Prachchhaana, S`hringa and Alaabu. Considering this scenario; one must try to obtain maximum information about the leech.
The word leech comes from an Old English word lacece meaning physician. In 1668 the veterinarian was known as a horse-leech. The spelling later became leech and was used to name a worm used in bloodletting. The leech belongs to the class Hirudinea and phylum Annelida. The technical name for the medicinal leech is Hirudo medicinalis.
Leeches are the only annelids with a fixed number (34) of body segments; each segment has secondary subdivisions known as annuli. A clitellum, less conspicuous than that of oligochaetes, is present; there are no parapodia. A leech has a small anterior sucker and a larger posterior one; the leech crawls by moving the anterior sucker forward attaching it, and drawing up the posterior sucker. Most leeches can swim by rapid undulations of the body, using well-developed muscles of the body wall.
The blood of some leeches is red. In others the blood lacks oxygen-carrying pigments and is therefore colorless; the oxygen dissolved directly in the blood is sufficient for respiration. Gas exchange occurs through the body surface of most leeches, although many fish parasitizing leeches have gills.
The sense organs consist of sensory cells of various types, including photoreceptor cells, scattered over the body surface. There are also 2 to 10 eyes, consisting of clusters of photoreceptor cells and located toward the front of the body.
Like the obligochaetes, leeches are hermaphroditic and cross-fertilizing, although fertilization is internal. In some species the sperm are enclosed in sacs, called spermatophores that are attached to the outside of the partner; the sperm pass through the body wall to the ovaries, where the eggs are fertilized. In other species the sperms are not enclosed and are transferred directly into the body of the partner by copulation. A courtship display is seen among some leeches at the time of mating. The fertilized eggs are deposited in a cocoon, secreted by the clitellum; the cocoon is buried in mud or affixed to submerged objects. The young emerge as small copies of the adults.
Toxic and medicinal leeches:
Medicinal leech has a cylindrical, dorsoventrally flattened body divided into 34 segments. The dorsal side is dark brown to black; bearing 6 longitudinal,, reddish or brown stripes and ventral surface is speckled. The anterior sucker surrounds the oral opening. The medicinal leech has 5 pairs of eyes located in front end.
For identifying toxic leeches; Sus`hruta had given appropriate description
Krishn`aa Dark black in colour and anterior sucker is larger in size
Karbura – Longer in size and instead of stripes on posterior surface, they possess elevated striations.
Alagardaa – More black anterior end and broader posterior sucker with hairs on the body. (This may be some other annelida organism, as leeches dont possess cilia on the body surface).
Indraayudhaa Multicoloured stripes on the body surface
Saamudrika Black body surface with yellowish spots.
Gochandana – Bifid posterior sucker.
Food of Leeches
While many aquatic leeches feed on the blood of fishes, amphibians, birds, mammals, snails, insect larvae, and worms. True land leeches feed only on the blood of mammals. Bloodfeeding leeches retain the solid parts of the blood as food in their very large crops, while the leechs kidneys eliminate the blood fluid. A leech can hold up to three times its weight in blood.
Parasitic leeches are equipped with a large (caudal) and a small (oral) sucker. The mouth is located on the small sucker and has three jaws with sharp teeth that make a Y- shaped incision in the flesh. When the leech punctures the sin it anesthetizes the wound with its saliva, so that often the victim doesnt feel the puncture. In addition, the leechs saliva dilates the blood vessels to increase blood flow and prevent the blood from clotting. The anticoagulant is called hirudin.
Once fulfilled with blood meal, leech takes about 3 to 6 months to digest it. It does not suffer from any disease like Indramada; but becomes useless to suck blood again for so long time. The blood; during this period; is prevented from coagulation and decay or infection. This mechanism is under research.
Blood-letting with leeches, and ancient medical practice that fell into disuse in the 19th century with the growth of pharmaceutical and homeopathic alternatives, has experienced a comeback since the 1980s, when applying leeches to patients after reconstructive surgery was found to help restore blood circulation and acceptance of the grafts.
Unless pre-treated with antibiotics, some patients receiving leech therapy suffer infection cased by Aeromonas Veronii, a bacterium that lives in the digestive tract of the leech.
George Graf, assistant professor of microbiology uses the leeches to study the interaction between bacteria and their hosts.
First, he is trying to understand how the bacteria Aeromonas live in leeches without harming them
A second, do the host and the bacterium need to have many different or may similar genes in order to establish a cooperative interaction?
Third, he is investigating why the gut of the leech is colonized by a single species of bacteria, and looking for possible anti-microbial agents that may prevent other microorganisms from colonizing the same area.
Personal modifications in practice
- Allow the wound to ooze
In Sus`hruta immediate turmeric packing at leech bite is not described.
¶ÉÉäÊhÉiÉºªÉ ªÉÉäMÉÉªÉÉäMÉÉxÉ´ÉäIªÉ S.Su.13/23
I dont make Vran`akarma at bite site immediately. I allow the wound to ooze for 10 15 m, sometimes even half an hour. Local cleaning of the oozing wound with cotton swab is continuous.
- Disposal of used leeches
For single patient, I recycle the leech for bloodletting in same patient. After his treatment is over, I dispose off the leech. I try to avoid cross use of leeches in two different patients.
This is a vast subject and needs extensive research as well as interactions in the experts.
Dr. Anand B. Barve
Last updated on February 23rd, 2021 at 08:41 am