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How about a blood-sucking leech instead of a pill?! They only have 300 teeth…

Posted by Amanda Ling on

When you hear the word leech, do your eyes bulge in horror and despair, or do you jump around with excitement at the thought of these little blood sucking wonders? Some two hundred years ago, leeches, more officially known as Hirudo Medicinalis, were at the centre of medical science. To be clear, we are not talking about mythical vampires here but referring to little worm-like looking creatures, with three-hundred teeth divided between three saw-like jaws, 32 brains, two reproductive organs and nine testes. If this description still has you jumping around with excitement, we’re impressed by your resolve!

There are over one thousand leech species, some reaching up to 20 cm in length, although the Amazonian leech can reach a jaw dropping 50 cm. I know, 50 cm!

Leeches are divided in two principal groups – the predacious leeches, which mainly feed on invertebrates, and the sanguivorous leeches, ectoparasites that feed on the blood of vertebrates – yes, humans included.

In 19th century Britain, the demand was so huge that leeches from Wales were no longer meeting medical demand! Farms were therefore created to supply hospitals, with the four main dealers in London handling in excess of seven million leeches a year, and this was still not enough. The challenge faced by farms was nourishing such a huge number of leeches. So cows, donkeys and other livestock would be used, with ‘leeches…attached like bunches of grapes to (their) belly and legs, with a sort of stupid surprise… A breeder…who has four hectares of marshes, drives into them every year upwards of 200 cows and dozens of donkeys for the nourishment of his 800,000 leeches'(7). I don’t know about you, but to us this sounds like the stuff of nightmares. As a result of demand far outweighing supply, Britain eventually imported some of the finest leeches from France, Russia and Poland…some 14 million each year.

Our Irish neighbours’ leeches were imported in large numbers, yet they were deemed to be of a lesser quality. So French leeches were the leech of supreme quality, and yet these were imported from Russia. It may not surprise you to know that leeches are still used today, farmed and studied in Russia, the U.S, and even the U.K. In fact, a few countries never stopped their research in this field. It may surprise you, however, to know that leeches are making a come back in the U.S, as a treatment of choice for various conditions, including cosmetic treatments.

So, what were leeches used for back in the ‘olden days’? To be leeched or not to be leeched, that’s the question. Leeches were used as far back 1600-1400 BC. The first records to depict the use of leeches were found in Ancient Egypt. In Ancient Greece, they were used for conditions such as phlebitis and haemorrhoids. Many illnesses were thought to be caused by an excess of blood or ‘bad blood’, which referred to blood infected by spirits. Doctors were not the only ones able to use leeches to cure all sort of conditions. Wait for it…Barbers were not just barbers back then, they could cut your hair, pull teeth out and partake in some blood-letting, using leeches. Now that’s what I call a service!

In Medieval Europe, English physicians were actually called ‘leeches’, such were their use of the little blood sucking annelids. In the 1800’s pneumonia, headaches, tonsillitis, and even cosmetic treatments were the remit of leeches. The use of 20 to 40 leeches were recommended for gastritis (1). Its use appeared to peak in 1830, France, when Brousias ‘the most sanguinary physician in history’ practised (1).

Another application was found in the field of dentistry, where leeches could be used on gums to drain abcesses, sublingual abcesses and even in pediatric for symptoms caused by teething. The thought of leeches on your skin is one thing however leeches in your mouth…I genuinely shudder at.

If you thought that Leech therapy was long relegated to past realms, think again. In 2004, Ricarimpex SAS, a French company received FDA approval for the commercial use of leeches in the U.S for medical purpose

What are modern leeches used for?

Medicine has moved on a little since then. If you are unfortunate enough to lose a digit, when and if it can be re-attached following some micro surgery, a leech can be applied to the re-attached digit. Any excess blood is drained away thereby promoting new fresh blood around the delicate tissues. Leeches secrete an anticoagulant, called hirudin and a vasodilator, which helps promote freshly oxygenated blood, to speed the healing process. Leeches have also been used for facial tissues replantation (tip of noses, ears, lips) and even penile replantation.

Research is being undertaken on the anticoagulant itself, for potential application in cardio vascular disease (CVD), stroke and even osteoarthritis. Apparently, ‘The saliva of leech contains numerous biologically active substances, which have anti-inflammatory as well as anaesthetic properties (2).

We mentioned that leeches can be used for finger or toe re-attachment, however their medical application in more modern times appears to extend to many other areas:

  • Cardiovascular diseases (CVDs): Leech saliva contains some anticoagulants, which have been the subject of much research, and shown to improve blood flow and improve connective tissue hyperalgesia. Meaning, it reduces the pain resulting from connective tissue diseases. One compound found in leeches’ saliva, is hirudin, and a few thrombotic drugs have been developed and used in the treatment of CVDs.
  • Varicose veins: A controlled study in 1998 found that the use of leeches in patients with varicose veins (with complications), was beneficial. 95% of patients reported a decrease in oedema, all ulcers reported healing, and 75% reported a decrease in hyperpigmentation (4).
    scabies, psoriasis, eczematous dermatitis, chronic ulcers, ring worms, reddish freckles and favus (5)
  • Cancer: Several studies have looked and are looking at the use of saliva extracts or leech extracts as antimetastatic agents, so not for the treatment of the tumor itself, but as an inhibitor for the proliferation or colonization of various organs such as lungs, bladder and breasts.
  • Diabetes mellitus (DM): Considered a pandemic of modern society, with an expected 366 million people suffering from diabetes by 2030. With its anticoagulant agents, leeches have been the object of many studies in the field of DM, particularly because patients suffering from diabetes are at an increased risk of CVDs but also suffer from poor blood flow to peripheral organs, which can be improved with the use of leeches, or some of its compounds.(6)
  • Infectious disease: This is another interesting area of research in the field of antimicrobial agents. With the extensive use of antibiotics in treating various infections, for ourselves and our food chain a new challenging phenomenon known as antibiotics resistance has emerged. Studies have looked at several agents found in leeches, known as antimicrobial peptides (AMPs), which appear to have a positive activity against various microbial strains.

The list of the potential medical applications of leeches is long and there are other areas which have been and are being investigated further, including Tinnitus, skin diseases, migraines and arthritis.

In conclusion, these little creatures are seriously impressive! Medical benefits appear to be abundant, and whilst I used to think that their uses were relegated to ancient medical books, it is truly incredible to see that Hirudo Medicinalis are still being farmed and researched today and contribute towards the advancement of modern medicine.

What about you? Have you ever used Hirudo therapy? What was your experience like? Would you consider leech therapy? We would love to hear your thoughts and comments.

  1. https://www.researchgate.net/profile/Younis_Munshi2/publication/2328407 8_Leeching_in_the_History-A_Review/links/580496a308ae6c2449f96b5d.pdf
  2. (Efficacy of leech therapy in the management of osteoarthritis https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3296343/)
  3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4717768/#b1
  4. https://www.ncbi.nlm.nih.gov/pubmed/9701897
  5. Ahmed T, Anwar M. Clinical importance of leech therapy. Indian Journal of Traditional knowledge. 2009;8(3):443–45. [Google Scholar]
  6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3757849/
  7. https://journals.sagepub.com/doi/pdf/10.1177/014107680109400114

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