This program provides a brief overview of the history of the medicinal use of leeches, as well as discussion regarding modern applications, patient assessment, guidance on performing leech therapy, and the after-treatment handling of leeches.
Upon completion of this program, the course participant will be able to:
Explain the four stages of successful leech therapy.
Identify contraindications of leech therapy.
Identify the risks and benefits of leech therapy.
Leech therapy, once thought of only as a good horror movie element, has experienced a modern medical practice revival across the United State and Europe. In 2004 the United States Food and Drug Administration officially approved leeches as a medical device 1, 13. However, leeches and the practice of placing living leeches on a patient (known as “leeching”), is by no means a new medicinal practice.
There is documented evidence of leeching dating back all the way to the beginning of the Common Era. Leeches have been used for centuries in nearly every major culture as a tool in “bloodletting” 5. Interestingly, bloodletting was the most common worldwide medical practice performed by physicians from antiquity until the late 19th century 5. Bloodletting is in essence the practice of withdrawing blood from a patient in order to cure or prevent illness and disease 5. Bloodletting and the use of leeches truly boomed in the early 19th century and thus made the production and sale of leeches a very profitable business. In fact, most of the modern large scale producers of medicinal leeches were founded in the early 1800’s.
Although the uses for leeches have evolved since antiquity, the actual species of leech used in Western Europe and America has remained the same. Hirudo Medicinalis, the European medicinal leech, is the most common leech used in modern medical practice 1, 2, 5. This leech is an aquatic segmented worm and can typically consume 5 -20 mL of blood in one application 5. The European Medicinal Leech has three jaws which each have approximately 100 teeth. This variety of leech releases an anesthetic into the wound when it bites, which helps to make the bite relatively painless 1, 2, 9. Once the leech has attached to the wound it naturally injects powerful compounds to help inhibit coagulation of the blood and sustain continuous blood flow:
Hirudin: a powerful anticoagulant and one of the most potent natural inhibitors of thrombin 5, 9.
Calin: an anticoagulant that prohibits the Von Willebrand factor to bind itself to collagen. This is also an effective inhibitor of the platelet aggregation caused by collagen5, 9.
Leech saliva also contains a naturally produced histamine-like substances that help to induce vasodilation 5, 6.
In regards to leech storage the modern leech farm facilities provide detailed protocols for their specific leeches. This normally includes a cool temperature (40-45 degrees Fahrenheit) within a storage container of a specific distilled water solution 1.
Leech therapy generally involves four main stages:
- The initial bite – typically painless due to the anesthetic that is secreted in the leech’s saliva.
- An attachment period – this can last from 15 minutes to 60 minutes 1. This is the period in which the leech is attached and sucking blood. A normal individual leech can consume between 5 -20mL of blood 1, 5, 6.
- Post Attachment period – At some point during the attachment period the leech will de-attach on its own when satiated. Feeding times vary – the patient should be instructed to notify the nurse as soon as a leech detaches. After the leech detaches the site will continue to bleed.
Note: It is not advisable to try and force the removal of leeches 1. In certain cases forced removal (with forceps or hands) damages the leeches and can even leave parts of the jaw and teeth attached to the site.
- Leech Disposal – Once the leech has detached on its own the leech can be placed in a small cup with alcohol 1, 5. The leech will die and should then be treated as bio-hazardous waste. Each cup should be labeled with patient’s name and the date.
Note: Leeches should never be reused on another person. Also, once a leech feeds and is full it will not be interested in feeding for several weeks 6.