LEECHES
Leeches are segmented, hermaphroditic worms. There are 650 known species of them. Some are quite specialized. One lives exclusively in the nostrils of Saharan camels. Another feed only on earthworms. Yet another feed on fishes found in freezing polar waters. Horse leeches can reach a length of eight inches. The largest species is found in the Amazon basin. It reaches a length of 18 inches and has an six-inch proboscis. .
New World leeches tend to track their hosts through the water. Old World leeches stalk their prey on land. Most species of leech like be near water.. They are found in ponds, wetland and tropical rainforests. In many places they appear in the rainy season and disappear in the dry season. Leeches are good swimmers. They swim like eels, except with their tails forward.
Leeches feed on other live animals, ether swallowing worms, snails of insect larvae or attaching themselves to a host and sucking their blood. A typical leech is one is one to 4 inches long and has suckers at each end of its body and has three jaws, arranged in a "Y," with sawlike teeth. It’s “brain” is a collection of 32 nerve bundles located in the middle of its body. If enough hosts are available a leech can live for five years.
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Leech Characteristics
Leeches are elongated and somewhat flattened. The suckers at the front and back of their body enables them to "inch" about by alternatively attaching and releasing suckers and extending and contracting their bodies." The suckers also allow them to grip their's host's skin while they drink blood.
Leeches can absorb oxygen through their body walls in both water and air. They were once placed in jars and used like barometers to predict the weather. When the parametric pressure fell, suggesting a strong possibility of rain, the leeches swim to the surface.
Leeches have pimple-like sense organs that can detect the heat of potential hosts and have stomachs that extend almost the entire lengths of their bodies. A leech can swell out its highly elastic body as if fills with blood with the help of numerous small sacs on its sides can increase with capacity.
Hermaphroditic leeches copulate on land by wrapping around each other, secreting mucus. Afterwards secrete a cocoon to house the fertilized eggs, which are deposited in damp soil. After two to four weeks about 15 to 20 inch-long baby leeches hatch and begin their quest for fresh blood. Under ideal conditions, a leech can produce 1,200 offspring in its five-year lifetime.
Leech Feeding
Leeches deliver an anesthetic, an antibiotic and chemicals that dilate blood vessels. Leeches fasten themselves with their hind suckers and suck the blood through little holes which they make in the skin with their 300 or sharp teeth with their tripartite jaw. Ducts between the teeth release compounds into the leech’s saliva that anesthetize the wound, prevent clotting and dilate vessels to increase blood flow. In some cases blood will continue to ooze up to 48 hours after the leech has been removed.
A leech typically needs 20 to 40 minutes to feed. When it is done it often increases in size tenfold. Some species swell up to the size of a cigar and prevent half a cup of blood from coagulating. One leech meal may last several months and take up to 18 months to completely digest. In that time the leech does little more than lie around and reproduce.
Leeches detect warmth, motion and shadows and drop off branches or find hosts from the ground. In the case of humans, they usually crawl up a host's leg from the ground and attach themselves to the first area of flesh the come to, usually above the socks. Leeches like earlobes, and burrowing between toes. They are capable of climbing on hammock strings to reach their victims. When leeches are full of blood they fall and the bleeding gradually stops Normally people stop bleeding after 10 minutes, but sometimes continue bleeding for up to 10 hours.
Some areas more infested than others. It is not unusual for people traveling in rain forests to pick off 20 leeches or more a day. To deter leeches keep moving and apply insect repellant to your shoes and socks and roll up your socks over you pants. Some people wear pantyhose to keep away leeches. In spite of leeches, many forest dwellers go barefoot Their advise with leeches is to "surrender what they want to them. If they feel happy, you will too."
Leeches can be detached by exposing them to a flame or sprinkling them with salt or alcohol. The methods employed regular visitors to swamps and rain forests is to burn it off with a lighter simply by holding the lighter next to the leech until in falls off. The bites don't hurt or itch but there is a possibility of infection if the a portion of the leach remain in the body. The bleeding can go on for 24 hours.
History of Leeches and Healing
For centuries physicians used leeches under the mistaken belief that they world help balance a patients’s body fluids or “humors.” George Washington is said to have died after doctors used leeches to drain huge quantities of blood during his illness.
Leeches were used by the pharaohs as a means or reducing blood pressure and were depicted on Egyptian tombs dated at 1500 B.C. Using leeches for bloodletting probably originated in ancient China and India.
In the Middle Ages leeches were used as a treatment for headaches and other disease. They became so linked with medicine that the Anglo-Saxon word for doctor and for leech were the same. In 17th and 18th century, leeches were used to treat nosebleeds, laryngitis, kidney infections, mental illness and variety of the ailments. France imported 41 million leeches in 1833.
Leeches and Healing Today
Today, leeches are used to increase circulation in severed limbs that have been reattached which is vital if the limb is survive. When reattaching or transplanting appendages blood-delivering arteries are relatively easy to stitch together because they have thick walls while blood-draining veins are more difficult to deal with because they have relatively thin walls and are frail, often clotting and turning blue after surgery, sometimes killing the new appendage. Leeches suck the blood, helping it circulate, reducing the pressure on veins, buying time for the body to create its own veins. Leeches also let a doctor now how well things are going because they won’t attach unless there is good arterial flow of blood.
The “Hirudo medicinalis” is the species of leech used most on medicine. It is five to 10 inches long. When it bites, substances in the saliva keeps the blood from clotting and keep blood oozing out for up to 48 hours after the leech has been removed. One woman who had her scalp reattached after it and her hair were pulled into a machine told Discover magazine, “I had them on my neck and back of my head. There was bucket of them in the room with me. Blood was pouring our of my scalp 24 hours a day for a week.”
Leeches are also the sources of new blood thinners and anticoagulants. Scientists have found disease-fighting peptides in leeches that are produced within 15 minutes and diffuse quicker and easier than antibodies. Scientists are also experimenting with producing leech compounds in mustard plants.
Leech Business
Biopharm in Swansea Wales is the main supplier of medical leeches in the world. Leeches are breed and raised on pig bloods. After about six months they stored in a cooling chamber with the temperatures set ast 45̊F. They can remain there for up to year without being fed.
Medicinal leeches cost about 30 cents to produce and are sold to doctors in the United States for between $6 and $9. Leeches sold by Leeches U.S.A. are delivered by a Federal Express and cost around $7 a piece.
Companies in France and the Ukraine make face creams for leeches.
Image Source: Centers for Disease Control and Prevention cdc.gov/DiseasesConditions
Text Sources: Centers for Disease Control and Prevention (CDC), U.S. Department of Health and Human Services; World Health Organization (WHO) fact sheets; National Geographic, New York Times, Washington Post, Los Angeles Times, The New Yorker, Time, Reuters, Associated Press, AFP, Lonely Planet Guides and various websites books and other publications.
Last updated May 2022