Leeches

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 25, 2022.

Clinical Overview

Use

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.

Dosing

Consult existing guidelines for the use of leeches.

Contraindications

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.

Pregnancy/Lactation

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

Interactions

None well documented.

Adverse Reactions

Extensive blood loss. Allergic reactions and infections may develop.

Toxicology

No data.

Biology

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.

History

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

Chemistry

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 ...