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LEECHES

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Classification   |    Detailed evidence-based information

Substances Included Synonyms

Therapeutic Toxic Class

    A) Medicinal leeches are being used in some clinical settings such as plastic and reconstructive surgery. Once venous congestion has been diagnosed the leech is applied directly to the site of greatest congestion.
    1) In many cases, new vessel, and growth around flap margins will restore effective venous draining within 3 days to a week.
    2) Specific contraindications to their use would be arterial insufficiency from either anatomic or mechanical obstruction (Wade et al, 1990).
    B) Leeches have been used medicinally since Nicander of Colophon in 200 to 130 BC. Although leeches have not been used frequently in modern medicine, there has been a resurgence of their use in surgical settings for post-operative wound healing.

Specific Substances

    A) CONSTITUENTS OF THE GROUP
    1) Amazon leech
    2) American leech
    3) Haementeria depressa
    4) Haementeria ghilianii (Amazon Leech)
    5) Hirudo (Macrobdella) decora (American Leech)
    6) Hirudo medicinalis
    7) Hirudo provincialis
    8) Hirudo officinalis
    9) Leech (medicinal)
    10) Medicinal leeches
    11) Myrobdella Africana (pharyngeal leech)

Available Forms Sources

    A) USES
    1) MEDICAL USES
    a) Medicinal leeches are finding use in repair of skin grafts, breast reconstruction, digital reimplantations, and periorbital hematomas (Dickson et al, 1984; Batchelor et al, 1984; Henderson et al, 1983; Derganc & Zdravic, 1960; Bunker, 1981).
    b) Hirudin, hementin, and leech hyaluronidase (Orgelase(R)) are being investigated clinically for use in disseminated intravascular coagulation (Adams, 1988; Anon, 1992).
    c) Medicinal leeches are sold by Leeches USA Ltd, of Westbury, New York. Leech-derived pharmaceuticals are being researched by Biopharm of Dyfed, Wales (Anon, 1992).
    d) The science of using medicinal leeches is called hirudinology (Cooper, 1989).
    2) LAY USES
    a) Leeches are not just used by physicians but have been purchased by the lay public for black eyes, varicose veins, and even depression (Adams, 1988).
    1) LEECH MAINTENANCE - Leeches can be maintained in a chlorine-free salt solution at 10 to 20 degrees C for up to 18 months (Anon, 1995).
    2) LEECH PRODUCTS - Hirucreme (France) and Exhirud (Germany) are hirudin containing leech extracts used topically as anticoagulants, anti-inflammatories, and anti-exudatives (Dejobert et al, 1991).

Overview

Life Support

    A) This overview assumes that basic life support measures have been instituted.

Clinical Effects

    0.2.1) SUMMARY OF EXPOSURE
    A) Medicinal leeches may be applied by a physician or a lay person. They also may become attached in their natural environment. The most common symptom is oozing or bleeding from the site of application. Leeches may remove 5 to 50 milliliters of blood each. Feeding is generally completed in 20 minutes.
    B) Infections may be caused by leaving a part of the leech in the wound during removal or by transferring contaminated blood. Scarring and allergic reactions may also occur.
    0.2.4) HEENT
    A) Leeches applied to the eyelids may produce ecchymosis.
    0.2.6) RESPIRATORY
    A) If the leech becomes attached to the upper airway, hemoptysis may occur.
    0.2.8) GASTROINTESTINAL
    A) Ingested leeches generally are killed by gastric acid. Care must be taken to observe that the leech has not attached to the esophagus. Leeches applied to the anus may migrate up the rectum and cause gastrointestinal bleeding.
    0.2.10) GENITOURINARY
    A) Leeches may migrate up the urinary tract and cause hematuria.
    0.2.13) HEMATOLOGIC
    A) Oozing or prolonged bleeding may occur after a leech has been removed. In some cases bleeding may continue for 24 hours. Leech infestation may result in fatal or near fatal anemia.
    0.2.14) DERMATOLOGIC
    A) Pain may occur with the attachment of some leeches; however, most leech attachments are painless. Scarring may occur in some cases.
    B) Contact dermatitis has been reported with leech containing topicals.
    0.2.19) IMMUNOLOGIC
    A) Various allergic reactions including anaphylaxis and local skin reactions have developed.

Laboratory Monitoring

    A) If blood loss is extensive, obtain a baseline CBC.

Treatment Overview

    0.4.2) ORAL/PARENTERAL EXPOSURE
    A) Emesis, activated charcoal, or lavage are generally not required.
    0.4.5) DERMAL EXPOSURE
    A) OVERVIEW
    1) Leeches should not be pulled off because of potential for leaving body parts in the wound. Matches, flames, or other heat sources should be avoided since they may burn the patient, as well as the leech.
    2) Salt or salt water, as well as vinegar, will cause an actively sucking leech to vomit and fall off.
    3) An actively sucking leech will generally become engorged in 15 to 20 minutes and then fall off.
    4) A patient should receive good wound care and tetanus prophylaxis.
    5) Various hemostatic measures have been used to stop oozing, including pressure, addition of fibrous material to the wound, tannic acid solutions, and silver nitrate. Ligature has also been used for some deep wounds.

Range Of Toxicity

    A) The number of leeches used medicinally will depend on the amount of blood to be removed. Each leech may remove approximately 5 to 15 mL of blood.

Clinical Effects

Summary Of Exposure

    A) Medicinal leeches may be applied by a physician or a lay person. They also may become attached in their natural environment. The most common symptom is oozing or bleeding from the site of application. Leeches may remove 5 to 50 milliliters of blood each. Feeding is generally completed in 20 minutes.
    B) Infections may be caused by leaving a part of the leech in the wound during removal or by transferring contaminated blood. Scarring and allergic reactions may also occur.

Heent

    3.4.1) SUMMARY
    A) Leeches applied to the eyelids may produce ecchymosis.
    3.4.3) EYES
    A) ECCHYMOSIS - Leeches applied to the eyelids may produce ecchymosis and edematous erysipelas (Adams, 1988).
    3.4.5) NOSE
    A) OBSTRUCTION - May occur if a leech enters a small place in the nostril, feeds and swells to a size that causes blockage (Adams, 1988).
    B) Epistaxis may occur when the leech attaches to the pharynx (Cundall et al, 1986).
    3.4.6) THROAT
    A) MYXOBDELLA AFRICANA - Also known as the pharyngeal leech, which usually attacks cattle, has been known to cause deaths in man (Cundall et al, 1986).

Respiratory

    3.6.1) SUMMARY
    A) If the leech becomes attached to the upper airway, hemoptysis may occur.
    3.6.2) CLINICAL EFFECTS
    A) HEMOPTYSIS
    1) Hemoptysis may occur when the leech attaches to the upper airway or pharynx (Adams, 1988; Estambale et al, 1992; Turner, 1969).
    B) AIRWAYS OBSTRUCTION REVERSIBLE
    1) A medicinally placed leech can cause blockage if the leech has obstructed an orifice (such as a nostril) after it is engorged (Coghlan, 1980; Stille & Maisch, 1884).

Gastrointestinal

    3.8.1) SUMMARY
    A) Ingested leeches generally are killed by gastric acid. Care must be taken to observe that the leech has not attached to the esophagus. Leeches applied to the anus may migrate up the rectum and cause gastrointestinal bleeding.
    3.8.2) CLINICAL EFFECTS
    A) GASTROINTESTINAL HEMORRHAGE
    1) SUMMARY
    a) Leeches applied to the anus may migrate into the rectum and cause gastrointestinal bleeding (Adams, 1988).
    2) CASE REPORT
    a) Following rectal infestation of a leech, an elderly woman developed rectal bleeding with fresh blood found in the rectum and sigmoid colon (Raj et al, 2000). Bleeding was controlled by endoscopic electrocoagulation of the lesion.

Genitourinary

    3.10.1) SUMMARY
    A) Leeches may migrate up the urinary tract and cause hematuria.
    3.10.2) CLINICAL EFFECTS
    A) BLOOD IN URINE
    1) Hematuria may be seen when leeches migrate up the urinary tract (Adams, 1988).

Hematologic

    3.13.1) SUMMARY
    A) Oozing or prolonged bleeding may occur after a leech has been removed. In some cases bleeding may continue for 24 hours. Leech infestation may result in fatal or near fatal anemia.
    3.13.2) CLINICAL EFFECTS
    A) HEMORRHAGE
    1) Oozing or prolonged bleeding may occur after the leech has been removed (Adams, 1988). In some cases bleeding may continue for up to 24 hours (Heldt, 1961). This may be exacerbated in patients with bleeding disorders (Legg, 1872).
    B) NORMOCYTIC HYPOCHROMIC ANEMIA
    1) Continued feeding of leeches may drop hemoglobin levels dramatically. A 5-day course drop of 1 to 2 g/dL is common, and a 7g/dL low was seen after a 6 day course (Rao, 1985).
    C) ANEMIA
    1) Fatal or near fatal anemia has been seen after vaginal and/or pharyngeal leech infestation (Estambale et al, 1992; Cundall et al, 1986). Anemia has also been reported following a rectal infestation in an elderly woman; a total of 4 units of blood was transfused (Raj et al, 2000).

Dermatologic

    3.14.1) SUMMARY
    A) Pain may occur with the attachment of some leeches; however, most leech attachments are painless. Scarring may occur in some cases.
    B) Contact dermatitis has been reported with leech containing topicals.
    3.14.2) CLINICAL EFFECTS
    A) HEMORRHAGE
    1) The most common symptom is oozing or bleeding from the site. Leeches may remove 5 to 15 mL of blood each (Stile & Maisch, 1884; (Pereira, 1854). Feeding is generally completed in 20 minutes (Anon, 1995).
    B) SKIN FINDING
    1) Scarring is not uncommon with leech use (Waring, 1866; Da Costa, 1907). The wounds may become ecchymotic with a triradiate scar.
    C) PAIN
    1) The attachment of most leeches is painless, while some leeches (like the horseleech) may cause painful wounds without attachment (Adams, 1988).
    D) CONTACT DERMATITIS
    1) Contact dermatitis has been reported to a leech extract (Hirucreme) which contains hirudin (Dejobert et al, 1991).
    2) Allergic contact dermatitis was suspected in an adult found with 38 empty leeches on his leg. Vesicular elements and itching occurred over several days (Tsyrkunov & Romanenko, 1984).
    E) LOCAL INFECTION OF WOUND
    1) Infection caused by leaving part of the leech in the wound during removal or by transferring contaminated blood via the leech may occur. Scarring and allergic reactions have also been observed (Adams, 1988; Anon, 1995).

Immunologic

    3.19.1) SUMMARY
    A) Various allergic reactions including anaphylaxis and local skin reactions have developed.
    3.19.2) CLINICAL EFFECTS
    A) ACUTE ALLERGIC REACTION
    1) Allergic reactions of various kinds, including anaphylaxis and local skin reactions have occurred (Heldt, 1961; Ross, 1983; Anon, 1995).

Laboratory Monitoring

Monitoring Parameters Levels

    4.1.1) SUMMARY
    A) If blood loss is extensive, obtain a baseline CBC.
    4.1.2) SERUM/BLOOD
    A) HEMATOLOGIC
    1) If blood loss has been extensive, obtain a baseline CBC.
    4.1.3) URINE
    A) URINALYSIS
    1) If it is suspected the leech may have migrated into the urinary tract, observe for gross hematuria and obtain a urinalysis.

Methods

    A) IMMUNOASSAY
    1) HIRUDIN - A quantitative enzyme-linked immunosorbent assay is available for hirudin (Spinner et al, 1986).

Treatment

Life Support

    A) Support respiratory and cardiovascular function.

Monitoring

    A) If blood loss is extensive, obtain a baseline CBC.

Oral Exposure

    6.5.2) PREVENTION OF ABSORPTION
    A) EMESIS
    1) Emesis is NOT necessary, even if a leech is ingested. It is generally thought that leeches can not withstand the gastrointestinal tract's acid and digestive enzymes. Older references suggested the ingestion of wine to treat ingested leeches (Adams, 1988).
    B) ACTIVATED CHARCOAL
    1) Activated charcoal is NOT necessary to treat an ingested leech.
    C) GASTRIC LAVAGE
    1) Gastric lavage is NOT necessary.
    6.5.3) TREATMENT
    A) COMPLICATION
    1) Swallowed leeches may attach to the esophagus. Observe for bleeding and obstruction. Once the leech is engorged (5 to 15 milliliters) it should detach and fall into the stomach. Complications might include obstruction or hemorrhage.
    B) DIRECT LARYNGOSCOPY WITH FOREIGN BODY REMOVAL
    1) Pharyngeal Leeches: Perform laryngoscopy. Sometimes the leech may be expelled by vomiting, or a forceps extraction under light general anesthesia may be necessary (Turner, 1969).
    C) REPLACEMENT BLOOD TRANSFUSION
    1) Blood transfusion may be necessary with severe or prolonged infection.

Dermal Exposure

    6.9.2) TREATMENT
    A) REMOVAL OF LEECHES
    1) DO NOT PULL THE LEECH OFF unless no other method is available. This may cause the leech's jaws to break off and serve as a source of infection.
    2) DO NOT USE A MATCH, FLAME, OR HEAT SOURCE to remove the leech unless no other methods are available. This may result in burns to the patient.
    3) Salt or salt water as well as vinegar will cause an actively sucking leech to vomit and fall off. These agents are generally safer than the methods above (Adams, 1988).
    4) An actively sucking leech will generally become engorged in 15 to 20 minutes, and then fall off (Adams, 1988).
    B) WOUND CARE
    1) A patient should receive good wound care and tetanus prophylaxis.
    C) ANTIBIOTIC
    1) Prophylactic antibiotics may be considered in patients exposed to leeches. A broad-spectrum antibiotic, such as an aminoglycoside or a third-generation cephalosporin, can be used to prevent infection by Aeromonas hydrophilia, found in the leech gut (Anon, 1995).
    D) BLEEDING
    1) Firm pressure may be enough to stop the bleeding.
    2) Various hemostatic measures and solutions have been recommended as well as fibrous materials, tannic acid solution and silver nitrate (Adams, 1988).
    3) Ligature was used for some deep wounds (Adams, 1988).
    E) Treatment should include recommendations listed in the ORAL EXPOSURE section when appropriate.

Range Of Toxicity

Toxicity Information

    7.7.1) TOXICITY VALUES
    A) R-HIRUDIN
    1) LD50- (SUBCUTANEOUS)RAT:
    a) >100 mg/kg (Klocking et al, 1990)

Summary

    A) The number of leeches used medicinally will depend on the amount of blood to be removed. Each leech may remove approximately 5 to 15 mL of blood.

Therapeutic Dose

    7.2.1) ADULT
    A) GENERAL
    1) Leeches do not require a prescription for use, however, Leeches USA prefers to distribute them to physicians or investigational hospitals exclusively. The leeches are shipped in a moist canvas bag, and these annelid worms are stored in a solution consisting of 2 grams Hirudo(R) salt per gallon of distilled water. They can remain usable for up to one year after purchase if their solution is changed weekly and they are either refrigerated or stored at room temperature. Each leech should only be used once and then disposed (Tech Info Medicinal Leeches, 1996) by placing in 70% alcohol for 5 minutes (Utley et al, 1998).

Maximum Tolerated Exposure

    A) ANIMAL DATA
    1) Rats given daily subcutaneous doses of r-hirudin 1 milligram/kilogram over 4 weeks showed no influence on general behavior or the development of normal body weight. The same was true to 10 milligrams/kilogram given subcutaneously (Klocking, 1991).

Pharmacology Toxicology

Pharmacologic Mechanism

    A) HIRUDIN -
    1) The salivary glands of leeches contain hirudin, a 65 amino acid polypeptide of a known amino acid sequence that reacts with thrombin (Harvey et al, 1986; Markwardt, 1985).
    2) Hirudin inhibits the conversion of fibrinogen to fibrin that is catalyzed by thrombin (Adams, 1988). As little as 1 microgram of hirudin may inhibit 10 units of thrombin (Harvey et al, 1986).
    3) Hirudin is secreted into the wound to prevent the blood from clotting (Lent, 1985). It was used as a natural anticoagulant prior to heparin (Satterlee & Hooker, 1915).
    4) The anticoagulant found in one leech could prevent the coagulation of 50 to 100 mL of blood (Heldt, 1961).
    5) Hirudin does not interfere with the biosynthesis of clotting factors or affect other blood enzyme systems (Markwardt et al, 1982).
    6) Native hirudin was difficult to obtain in quantity; recombinant hirudin (r-hirudin) is now available (Klocking, 1991). There are several forms of hirudin, which can be separated by HPLC (Walsmann, 1991).
    7) The LD50 of r-hirudin in mice was greater than 250 mg/kg (Klocking, 1991).
    8) Hirudin appears to be a weak immunogen (Klocking, 1991; Spinner et al, 1986; Markwardt et al, 1988a).
    B) HEMETIN -
    1) The substance hemetin (found in Haementeria ghilianii) causes the proteolysis of host fibrinogen rather than interference with fibrinogen to prevent clotting.
    2) There is enough anticoagulant in one of the Amazon leeches to inhibit clotting of 300 mL of blood (Sawyer, 1986).
    C) PLASMINOGEN ACTIVATOR -
    1) Still another mechanism used by leeches (Haementeria depressa) is similar to streptokinase. The substances are plasminogen activatorS (Sawyer, 1986).
    D) HYALURONIDASE -
    1) May also be found in leech secretions, and may act as a spreading factor in the wounds they make (Linker et al, 1960) Yuki & Fishman, 1903; (Claude, 1937; Favilli, 1940).
    2) It breaks up a constituent connection tissue and is being investigated as a treatment for myocardial infarcts (Anon, 1992).
    E) OTHER POTENTIAL ACTIVE CONSTITUENTS -
    1) Include an antihistamine (Sawyer, 1986; Lindeman, 1939); proteinase inhibitors such as dbellins (Adams, 1988), trypsin-plasmin inhibitors (Fritz et al, 1971), eglins, chymotrypsin inhibitors, various proteases (Adams, 1988), anesthetics (Sawyer, 1986; Lenggenhager, 1936), and many others.

Animal Toxicology

Clinical Effects

    11.1.1) AVIAN/BIRD
    A) ANEMIA - Leeches may cause anemia in waterfowl (Grafner et al, 1988; Hosie, 1989).
    B) TISSUE DAMAGE - Inflammation of the nasal and oral cavities due to leech infestation has been noted in waterfowl (Roberts, 1955; Lang, 1969; Tuggle, 1987).
    C) OCULAR DAMAGE - Leeches have produced corneal opacity and blindness in waterfowl (Roberts, 1955; Lang, 1969; Tuggle, 1987).
    D) PARASITE TRANSMISSION - Various trematodes (Cotylurus and Apatemon species) and cestodes (Hymenolepsis parvula) may be transmitted by certain leech species (Mann, 1962).
    11.1.2) BOVINE/CATTLE
    A) ANEMIA - Leeches may cause anemia in ruminants (Mahato, 1989).
    B) MYXOBDELLA AFRICANA - Also known as the pharyngeal leech, which usually attacks cattle, has been known to cause deaths in man (Cundall et al, 1986).
    11.1.7) ICHTHYOID/FISH
    A) SKIN ULCERATION has been seen in fish (Roberts, 1978).
    B) PARASITE TRANSMISSION - Various blood protozoa (Trypanosoma species and Haemohormidium species) may be transmitted to fish via leeches (Sawyer, 1986).
    11.1.11) REPTILE
    A) REPTILE
    1) PARASITE TRANSMISSION - Various blood protozoa such as Haemogregarina species have been transmitted to reptiles by leeches (Cooper, 1990; Tse et al, 1986).
    11.1.13) OTHER
    A) OTHER
    1) Leeches may obstruct the respiratory tract (Mahato, 1989).
    2) PARASITE TRANSMISSION - Various blood protozoa such as Trypanosoma, Aegyptianella and Lankesterella have been transmitted to amphibians (Desser, 1987; Cooper, 1990).

Sources

    A) GENERAL
    1) Although leeches are not commonly used in veterinary medicine, there is interest in investigating their use for certain procedures such as skin grafts (Cooper, 1990).

References

General Bibliography

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