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  1. Leach definition is - either vertical edge of a square sail. How to use leach in a sentence.
  2. The medicinal leech has proved useful in medicine because of its peculiar mouthparts and the pharmacologically active substances present in its saliva. Hirudo medicinalis has three jaws with approximately 100 sharp teeth on each outer rim. The leech feeds by first attaching its sucker onto the skin. The mouth, located in the middle of the sucker, opens to expose the teeth, which cut into the.
  3. Aug 09, 2020 The Leech's healing effect does not affect characters that do not have red heart containers. Keeper will be healed by The Leech. Enemies that turn into flesh piles and regenerate when killed such as Globins and some dark red champions regenerate quicker than the Leech can kill them. Isaac will gain half a heart each time the enemies collapse.

Leech, (subclass Hirudinea), any of about 650 species of segmented worms (phylum Annelida) characterized by a small sucker, which contains the mouth, at the anterior end of the body and a large sucker located at the posterior end. All leeches have 34 body segments. The length of the body ranges. Feb 25, 2019 'The sun rose in a cloudless sky, the same as before. We passed a large island without grass or tree or bush. The sun was a leech that sucked the moisture from our flesh.' (Scott O'Dell, The King's Fifth. Houghton Mifflin, 1966) 'She called him a leech, said he's always sponging off the rest of us.' (Swati Kaushal, A Girl Like Me. Penguin, 2008).


to dissolve out substances; to percolate
Not to be confused with:


v.leached, leach·ing, leach·es
1. To remove soluble or other constituents from by the action of a percolating liquid: heavy rains that leached the soil of minerals.
2. To remove from a substance by the action of a percolating liquid: acids in groundwater that leach calcium out of the bedrock.
3. To empty; drain: 'a world leached of pleasure, voided of meaning'(Marilynne Robinson).
To be dissolved or passed out by a percolating liquid.
2. A porous, perforated, or sievelike vessel that holds material to be leached.
3. The substance through which a liquid is leached.
[From Middle English leche, leachate, from Old English *lece, muddy stream; akin to leccan, to moisten.]
leach′a·ble adj.



Live Bait Leeches For Sale

liːtʃ) vb
1. to remove or be removed from a substance by a percolating liquid
2. to lose or cause to lose soluble substances by the action of a percolating liquid
5. a substance that is leached or the constituents removed by leaching
[C17: variant of obsolete letch to wet, perhaps from Old English leccan to water; related to leak]




(liːtʃ) n
(Biography) Bernard (Howell). 1887–1979, British potter, born in Hong Kong


1. to dissolve out soluble constituents from (ashes, soil, etc.) by percolation.
2. to cause (water or other liquid) to percolate through something.
3. (of ashes, soil, etc.) to undergo the action of percolating water.
5. a leaching.
7. a vessel for use in leaching.
[1425–75; late Middle English leche leachate, infusion]


To remove the soluble materials from a substance, such as ash or rock, by passing a liquid through or over it: Heavy rains leached minerals from the soil.


Past participle: leached
Gerund: leaching
I leach
you leach
he/she/it leaches
we leach
you leach
they leach
I leached
you leached
he/she/it leached
we leached
you leached
they leached
Present Continuous
I am leaching
you are leaching
he/she/it is leaching
we are leaching
you are leaching
they are leaching
Present Perfect
I have leached
you have leached
he/she/it has leached
we have leached
you have leached
they have leached
Past Continuous
I was leaching
you were leaching
he/she/it was leaching
we were leaching
you were leaching
they were leaching
Past Perfect
I had leached
you had leached
he/she/it had leached
we had leached
you had leached
they had leached
I will leach
you will leach
he/she/it will leach
we will leach
you will leach
they will leach
Future Perfect
I will have leached
you will have leached
he/she/it will have leached
we will have leached
you will have leached
they will have leached
Future Continuous
I will be leaching
you will be leaching
he/she/it will be leaching
we will be leaching
you will be leaching
they will be leaching
Present Perfect Continuous
I have been leaching
you have been leaching
he/she/it has been leaching
we have been leaching
you have been leaching
they have been leaching
Future Perfect Continuous
I will have been leaching
you will have been leaching
he/she/it will have been leaching
we will have been leaching
you will have been leaching
they will have been leaching
Past Perfect Continuous
I had been leaching
you had been leaching
he/she/it had been leaching
we had been leaching
you had been leaching
they had been leaching
I would leach
you would leach
he/she/it would leach
we would leach
you would leach
they would leach
Past Conditional
I would have leached
you would have leached
he/she/it would have leached
we would have leached
you would have leached
they would have leached
Noun1.leach - the process of leaching
natural action, natural process, action, activity - a process existing in or produced by nature (rather than by the intent of human beings); 'the action of natural forces'; 'volcanic activity'
Verb1.leach - cause (a liquid) to leach or percolate
remove, take away, withdraw, take - remove something concrete, as by lifting, pushing, or taking off, or remove something abstract; 'remove a threat'; 'remove a wrapper'; 'Remove the dirty dishes from the table'; 'take the gun from your pocket'; 'This machine withdraws heat from the environment'
2.leach - permeate or penetrate gradually; 'the fertilizer leached into the ground'
dribble, trickle, filter - run or flow slowly, as in drops or in an unsteady stream; 'water trickled onto the lawn from the broken hose'; 'reports began to dribble in'
3.leach - remove substances from by a percolating liquid; 'leach the soil'
remove, take away, withdraw, take - remove something concrete, as by lifting, pushing, or taking off, or remove something abstract; 'remove a threat'; 'remove a wrapper'; 'Remove the dirty dishes from the table'; 'take the gun from your pocket'; 'This machine withdraws heat from the environment'


verbextract, strain, drain, filter, seep, percolate, filtrate, lixiviate(Chemistry)Minerals leach from the soil much faster on cleared land.


verbTo flow or leak out or emit something slowly:
bleed, exude, ooze, percolate, seep, transpire, transude, weep.




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Scientific Name(s): Hirudo medicinalis L. Phylum: Annelida.
Common Name(s): Fresh water leech, Medicinal leech

Medically reviewed by Drugs.com. Last updated on Apr 24, 2020.

Clinical Overview



Leeches have been used for bloodletting, wound healing, and stimulating blood flow at postsurgical sites. Use in osteoarthritis is being investigated, but there is a lack of clinical information to make recommendations.


Consult existing guidelines for the use of leeches.


Arterial insufficiency, previous exposure to leeches (risk of allergic reaction), immunosuppression (risk of infection), patient refusal to accept possible subsequent blood transfusions, and unstable medical conditions have been described as contraindications for extensive leech therapy.

Leech Therapy


Information regarding safety in pregnancy and lactation is lacking. Avoid use because of risk of infection and anemia.


None well documented.

Adverse Reactions

Extensive blood loss. Allergic reactions and infections may develop.


No data.


There are more than 700 species of leeches, all of which are carnivorous.1 The leech is an hermaphrodite, containing both male and female sexual organs, but is not self-fertile.

The use of medicinal leeches (H. medicinalis) is preferred because of their ability to bite deeply and cause prolonged bleeding even after they are detached. H. medicinalis can reach up to 12 cm long, but is generally smaller, weighing 1 to 1.5 g before feeding. H. medicinalis has both anterior and posterior suckers, with the head located at the narrow tapered end. The anterior sucker has 3 jaws, each with 60 to 100 teeth for biting. The posterior sucker is used for attachment and crawling.1

Leeches obtained from commercial breeders are easily maintained in a chlorine-free salt solution at 10° to 20°C. Under such conditions, leeches can survive for up to 18 months.


The medicinal use of leeches dates back to ancient Egyptians around 1300 BC; the Greek physician Galen (130 to 201 AD) commonly used leeches for bloodletting. The 19th century heralded the widespread use of leeches for bloodletting—leading to a leech shortage from 1825 to 1850 in France requiring the importation of leeches from America.1, 2, 3, 4, 5, 6 By the end of the 19th century, the medicinal use of leeches had lost popularity due to adoption of the modern concepts of pathology and microbiology.1


Different species of leeches secrete varying compounds with differing hematological actions.7, 8

Following attachment, H. medicinalis secretes hirudin, a selective thrombin inhibitor, which enhances bleeding and prevents coagulation.1, 9, 10 Hirudin was first described more than a century ago and characterized as a 65-amino acid peptide with antithrombokinase activity.1 Early therapeutic studies of hirudin were limited by low natural yield, but the compound has recently been produced in larger quantities by recombinant gene techniques.11, 12 Recombinant hirudin binds avidly to thrombin, thus low doses inhibit venous thrombosis in animals. Extracts from leeches have been marketed in creams for topical application. In addition to hirudin, leeches secrete hirustasin, which selectively inhibits tissue kallikreins; antistasin and ghilanten, which inhibit Factor Xa; calin, apyrase, and saratin, which inhibit platelet aggregation; a histamine-like compound, which causes vasodilation; hyaluronidase and collagenase, which increase permeability; and bdellin and eglin, which are proteinase inhibitors.1, 10, 13, 14

There is conflicting evidence as to whether an anesthetic is secreted in H. medicinalis.4, 15, 16 Theromyzon is widely distributed in the tissue of the leech Theromyzon tessulatum and has angiotensin-converting, enzyme-like properties8 and peptides with antimicrobial properties have been identified.17

Undefined anti-inflammatory substances in the saliva of medicinal leeches have been reported.18, 19

Uses and Pharmacology

Ischemic tissue

Medicinal leeches are used to stimulate the flow of blood at postoperative surgical sites.2, 15, 16

After attaching to the site, leeches secrete compounds, especially hirudin, that reduce blood viscosity. They provide the drainage needed to permit decongestion and to preserve tissue viability until normal venous flow is established.16, 20

Reviews of the use of 'hirudotherapy' in localized venous congestion or hematoma have been published; most commonly, only case reports exist in the literature.18, 21, 22

Other uses

Based on reported anti-inflammatory substances in the saliva of medicinal leeches, a number of clinical studies have evaluated the role of leeches in osteoarthritis.18, 19 Blinding of participants is problematic in such studies and comparators have used transcutaneous electrical nerve stimulation (TENS)23 and topical diclofenac.24 A meta-analysis of clinical studies (n=4) reported moderate to strong evidence for pain reduction, functional impairment, and joint stiffness following leech therapy.19


Institutional guidelines may exist for the use of leeches. Leeches are applied from 2 to 4 times a day for up to a week. Feeding is complete in about 20 minutes, at which time the leech drops off. Removal of the leech may be hastened by applying solutions of salt, vinegar, a flame, or a local anesthetic. Leeches should not be forcibly removed. Bleeding from the attachment site usually continues for several hours. Reuse of leeches is discouraged to minimize the development of cross-infection.1, 20, 25, 26

Pregnancy / Lactation

Information regarding safety in pregnancy and lactation is lacking. Avoid use due to risk of infection and anemia.


None well documented. Closely monitor conditions requiring concomitant anticoagulant therapy.

One study found no changes in ipsilateral activated partial thromboplastin or prothrombin times when leeches were applied to an intact hand. This suggests that systemic or local anticoagulation is not likely to occur and that the risk of interference with other therapies may be small.27

Adverse Reactions

Arterial insufficiency, previous exposure to leeches (risk of allergic reaction), immunosuppression (risk of infection), patient refusal to accept possible subsequent blood transfusions, and unstable medical conditions have been described as contraindications for extensive leech therapy.9 Datascope anestar service manual online.

Blood loss

Leeches may consume up to 50 mL blood per application, and their secretions during a single feed can prevent coagulation (in vitro) of up to 100 mL human blood. Passive bleeding after detachment can continue up to 72 hours but most commonly continues for about 5 hours. Blood loss may occur, sometimes requiring transfusions.18, 28


H. medicinalis should be considered a possible vector of infectious diseases. The incidence of infection consequent to leech therapy ranges from 2% to 20%.21, 22

The gram-negative Aeromonas hydrophilia is the predominant microbial species found in leeches.1, 9, 29, 30 Serratia, Klebsiella, and Pseudomonas have also been isolated10, 31, 32, 33, 34 and patients should receive appropriate prophylactic antibiotic therapy. Older studies suggested possible transmission of HIV and hepatitis, but this is less likely with the use of farmed leeches.22, 35 Reuse of leeches is not recommended due to concerns of disease transmission.4


Local allergic reactions and anaphylaxis have been reported.36 Leeches found in the nose, throat, and the GI tract have caused complications.37, 38, 39, 40


No data.


1. Whitaker IS, Cheung CK, Chahal CA, Karoo RO, Gulati A, Foo IT. By what mechanism do leeches help to salvage ischaemic tissues? A review. Br J Oral Maxillofac Surg. 2005;43(2):155-160.157492172. Hayden RE, Phillips JG, McLear PW. Leeches. Objective monitoring of altered perfusion in congested flaps. Arch Otolaryngol Head Neck Surg. 1988;114(12):1395-1399.31908663. Rao J, Whitaker IS. Use of Hirudo medicinalis by maxillofacial surgical units in the United Kingdom: current views and practice. Br J Oral Maxillofac Surg. 2003;41(1):54-55.4. Whitaker IS, Izadi D, Oliver DW, Monteath G, Butler PE. Hirudo medicinalis and the plastic surgeon. Br J Plast Surg. 2004;57(4):348-353.151457395. Ventura HO, Mehra MR. Bloodletting as a cure for dropsy: heart failure down the ages. J Card Fail. 2005;11(4):247-252.158803326. Hodgson D. Of gods and leeches: treatment of priapism in the nineteenth century. J R Soc Med. 2003;96(11):562-565.145949727. Ledizet M, Harrison LM, Koskia RA, Cappello M. Discovery and pre-clinical development of antithrombotics from hematophagous invertebrates. Curr Med Chem Cardiovasc Hematol Agents. 2005;3(1):1-10.8. Rivière G, Michaud A, Deloffre L, et al. Characterization of the first non-insect invertebrate functional angiotensin-converting enzyme (ACE): leech TtACE resembles the N-domain of mammalian ACE. Biochem J. 2004;382(pt 2):565-573.151750049. Chepeha DB, Nussenbaum B, Bradford CR, Teknos TN. Leech therapy for patients with surgically unsalvageable venous obstruction after revascularized free tissue transfer. Arch Otolaryngol Head Neck Surg. 2002;128(8):960-965.1216277910. Dippenaar R, Smith J, Goussard P, Walters E. Meningococcal purpura fulminans treated with medicinal leeches. Pediatr Crit Care Med. 2006;7(5):476-478.1687804911. Wallis RB. Hirudins and the role of thrombin: lessons from leeches. Trends in Pharmacol Sci. 1988;9(12):425-427.307808112. Hand R, et al. A review of the pharmacology, clinical applications, and toxicology of hirudin and hirulog. Transgenica: J Clin Biotechnol. 1994;1:1.817222513. Deckmyn H, Stassen JM, Vreys I, Van Houtte E, Sawyer RT, Vermylen J. Calin from Hirudo medicinalis, an inhibitor of platelet adhesion to collagen, prevents platelet-rich thrombosis in hamsters. Blood. 1995;85(3):712-719.783347514. Harsfalvi J, Stassen JM, Hoylaerts MF, et al. Calin from Hirudo medicinalis, an inhibitor of von Willebrand factor binding to collagen under static and flow conditions. Blood. 1995;85(3):705-711.783347415. Baskova IP, Khalil S, Nartikova VF, Paskhina TS. Inhibition of plasma kallikrein, kininase and kinin-like activities of preparations from the medicinal leech. Thrombosis Research. 1992;67(6):721-730.144053716. Rados C. Beyond bloodletting: FDA gives leeches a medical makeover. FDA Consum. 2004;38(5):9.1559514117. Salzet M. Neuropeptide-derived antimicrobial peptides from invertebrates for biomedical applications. Curr Med Chem. 2005;12(26):3055-3061.1637570018. Porshinsky BS, Saha S, Grossman MD, Beery Ii PR, Stawicki SP. Clinical uses of the medicinal leech: a practical review. J Postgrad Med. 2011;57(1):65-71.2120611519. Lauche R, Cramer H, Langhorst J, Dobos G. A systematic review and meta-analysis of medical leech therapy for osteoarthritis of the knee. Clin J Pain. 2014;30(1):63-72.2344606920. Abrutyn E. Hospital-associated infection from leeches. Ann Intern Med. 1988;109(5):356-358.304421021. Elyassi AR, Terres J, Rowshan HH. Medicinal leech therapy on head and neck patients: a review of literature and proposed protocol. Oral Surg Oral Med Oral Pathol Oral Radiol. 2013;116(3):e167-e172.2281946222. O'Dempsey T. Leeches--the good, the bad and the wiggly. Paediatr Int Child Health. 2012;32(suppl 2):S16-S20.2339475423. Stange R, Moser C, Hopfenmueller W, et al. Randomised controlled trial with medical leeches for osteoarthritis of the knee. Complement Ther Med. 2012;20(1-2):1-7.2230524224. Michalsen A, Klotz S, Lüdtke R, Moebus S, Spahn G, Dobos GJ. Effectiveness of leech therapy in osteoarthritis of the knee: a randomized, controlled trial. Ann Intern Med. 2003;139(9):724-730.1459745625. Adams SL. The emergency management of a medicinal leech bite. Ann Emerg Med. 1989;18(3):316-319.292334026. Rao P, Bailie FB, Bailey BN. Leechmania in microsurgery. Practitioner. 1985;229(1408):901-905.405917027. Blackshear JL, Ebener MK. Leeching, hirudin, and coagulation tests. Ann Intern Med. 1994;121(2):151-152.801773528. Ikizceli I, Avsarogullari L, Sözüer E, Yürümez Y, Akdur O. Bleeding due to a medicinal leech bite. Emerg Med J. 2005;22(6):458-460.1591196529. Ardehali B, Hand K, Nduka C, Holmes A, Wood S. Delayed leech-borne infection with Aeromonas hydrophilia in escharotic flap wound. J Plast Reconstr Aesthet Surg. 2006;59(1):94-95.1648279630. Steer A, Daley AJ, Curtis N. Suppurative sequelae of symbiosis. Lancet. 2005;365(9454):188.1563930331. Dickson WA, Boothman P, Hare K. An unusual source of hospital wound infection. Brit Med J. 1984;289(6465):1727-1728.644062332. Kourt B, Segars LW, Davis TW. When the prescription says 'leeches.' Am J Hosp Pharm. 1994;51(17):2113-2114, 2116.798568533. Bickel KD, Lineaweaver WC, Follansbee S, Feibel R, Jackson R, Buncke HJ. Intestinal flora of the medicinal leech Hirudinaria manillensis. J Reconstr Microsurg. 1994;10(2):83-85.818256934. Wilken GB, Appleton CC. Bacteriological investigation of the occurrence and antibiotic sensitivities of the gut-flora of the potential southern African medicinal leech, Asiaticobdella buntonensis (Hirudinidae). J Hosp Infect. 1993;23(3):223-228.809909635. Nehili M, Ilk C, Mehlhorn H, Ruhnau K, Dick W, Njayou M. Experiments on the possible role of leeches as vectors of animal and human pathogens: a light and electron microscopy study. Parasitol Res. 1994;80(4):277-290.807301336. Tseng CC, Ho CY. Removal of a nasal leech: a safe and effective method. Otolaryngol Head Neck Surg. 2005;132(5):814-815.1588664437. Bergua A, Vizmanos F, Monzón FJ, Blasco RM. Unavoidable epistaxis in the nasal infection of leeches [in Spanish]. Acta Otorrinolaringol Esp. 1993;44(5):391-393.812997738. Uygur K, Yasan H, Yavuz L, Dogru H. Removal of a laryngeal leech: A safe and effective method. Am J Otolaryngol. 2003;24(5):338-340.1313044839. Kuehnemund M, Bootz F. Rare living hypopharyngeal foreign body. Head Neck. 2006; 28(11):1046-1048.1693331440. Krüger C, Malleyeck I, Olsen OH. Aquatic leech infestation: a rare cause of severe anaemia in an adolescent Tanzanian girl. Eur J Pediatr. 2004;163(6):297-299.15346909


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