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Leeches suck on the blood of fish, animals and people to survive. To do this, they inject a natural anticoagulant called hirudin into their prey. This anticoagulant prevents blood clots from forming and thins the blood to improve blood supply (and as an unintended consequence, blood circulation).

These qualities of leech saliva have piqued the interest of some people in the medical community. Particularly for medical purposes like microsurgeries (for example, finger reattachment surgery) where the surgeons want continued blood supply to tissues to prevent tissue death and promote wound healing.

Leech therapy is also emerging as an alternative treatment to prevent amputation of limbs in uncontrolled and advanced diabetes, the resolution of varicose veins (a painful swelling of the veins, usually in the legs), and Berger’s disease (a condition in which IgA immune cells collect in the kidneys).

Though more research needs to go into this, leech saliva is thought to have anti-inflammatory properties, too. For this reason, some alternative healers have been using leeches for the treatment of osteoarthritis.

Of late, researchers have tried to make synthetic hirudin—the naturally occurring peptide that gives leech saliva its anticoagulant properties—but this hasn’t been very effective. They have also tried to extract hirudin from leeches. But this process, too, has proven to be inefficient for commercial use so far. Until this can change, applying medical leeches to the affected body part will of necessity remain the primary way to administer this therapy.

The US Food and Drug Administration has given approval to leech therapy as “an adjunct to the graft tissue healing when problems of venous congestion may delay healing, or to overcome the problem of venous congestion by creating prolonged localized bleeding”.

Essentially, leeches may be used as a medical device to drain excess blood in a recently reattached finger/toe/ear/lip/nose, etc.

That said, it is important to remember that leech therapy is not the first line of treatment in any disease or condition. It is an alternative (and inexpensive) method that can be useful in very specific scenarios and when done by a trained practitioner only. It should not replace or interfere with your allopathic medicines and therapies.

Read on to know more about leech therapy.

  1. What is leech therapy and how is it done?
  2. Benefits of leech therapy
  3. Side effects of leech therapy

Leech therapy comprises the direct application of medical leeches to the area that needs treatment. It is done by a surgeon or doctor for very specific purposes. For example, medical leeches, usually Hirudo medicinalis, can help in improving the prognosis in diabetic foot ulcer and avoiding amputation in select cases.

Indeed, scientists are also looking into other health conditions where blood clots and poor circulation are a problem, and where leech therapy may help.

The main therapeutic effect of this is said to come from anticoagulants, anti-inflammatory enzymes and anti-elastase in leech saliva.

Leech therapy is far from new. Indeed bloodletting has been used in traditional medicine systems from India (Ayurveda) to ancient Egypt. What is different now is that we know today that general bloodletting does not have therapeutic effects. We also know that we need to watch out for side effects like bacterial infections.

How is leech therapy done

There are different medical leeches, depending on which part of the world they’re sourced from. That said, most medical leeches today are sourced from Europe. 

Medical leeches have three jaws, each with about 100 "teeth". Each adult leech can suck up to 15ml of blood in one sitting.

The leeches are simply applied to the affected area. Where the leech feeds, it leaves a "Y" shaped surface wound. The process is usually painless (leech saliva is also said to have a mild anaesthetic effect), though some people may experience minor discomfort.

Each leech feeds for about 40 minutes, after which the leech falls off on its own.

Who cannot get leech therapy?

People who have health conditions like haemophilia (a blood clotting disorder), anaemia or leukaemia should not undergo leech therapy. Additionally, pregnant women and children cannot be given this therapy.

Hirudotherapy or leech therapy is mainly used in modern medicine for reattachment of digits (fingers and toes), ears, lips, noses. The leeches drain the extra blood and prevent tissue death, as the newly reattached body part rebuilds connections between the blood vessels.

Additionally, leech saliva contains small-chain proteins (peptides) that are said to have anticoagulant (anti-clotting), anaesthetic (numbing), antihistamine (anti-allergy) and vasodilatory (dilates the blood vessels) effects. These properties can help in improving blood circulation to peripheral body parts (farthest from the heart).

Here are some of the most common uses of leech therapy today:

Leech therapy for micro surgeries like ear reattachment

The US FDA has approved leech therapies for plastic surgeries such as reattachment of fingers and toes.

There are two ways in which leeches can help in these situations:

  • The anticoagulants in leech saliva prevent blood clots from forming, so the detached tissue can be reattached and the blood vessels reconnected without much difficulty.
  • Sometimes when body parts are reattached after an accident, there can be a mismatch in the amount of blood flowing in through the arteries and out through the veins. Bloodletting allows surgeons to drain the extra blood in that specific area and give the tissue enough time to heal and remake the proper connections in blood vessels

Leech therapy for diabetes

People with diabetes often have sluggish blood flow to the ends of the body—the fingers and toes, for example. The application of leeches to these parts is said to draw the blood towards them. It is also said to reduce the pressure on the heart by the injection of anti-blood-clotting proteins.

More studies need to be done on this, but some doctors have reported that the application of leeches may even clear the infection out of dying tissue and prevent the need for amputation in some cases.

Other leech therapy benefits

Leech therapy is mainly authorized for reconstruction plastic surgery. However, researchers are looking into other potential benefits of applying leeches, too.

Leech therapy for osteoarthritis

Osteoarthritis is typically age-related. It is marked by inflammation, stiffness and pain in the joints. A study by researchers at the Banaras Hindu University with 32 men aged 40-80 found that after six weekly sittings in which leeches were applied to the affected area, patients reported significant improvement in joint pain and joint stiffness.

Leech therapy for joint pain and arthritis is an Ayurveda therapy. It is believed that leech saliva has anti-inflammatory and anaesthetic properties which help patients with this condition. More research needs to be done on this.

Researchers have also found that leech saliva contains two substances called Eglin and Bdellin (a protease inhibitor) which help to reduce inflammation.

Leech therapy for disorders linked to blood

Hirudin in leech saliva works as an anticoagulant. The destabilase enzyme in leech saliva is said to break blood clots. Apyrase in leech saliva is said to inhibit the collection of platelets at the injury site and make the blood flow. Further, the sucking action of the leech is said to pull blood even from the deeper tissues. For these reasons, leech therapy is said to be useful in conditions like varicose veins, and hypertension.

Leech therapy for the kidneys

Researchers are looking into the reason for it, but leech therapy has been found to be useful in Immunoglobulin A nephropathy (IgAN) by reducing fibrosis or scarring of tissue and reducing inflammation.

One of the main side effects of leech therapy is bacterial infection, sometimes by drug-resistant bacteria.

Excessive bleeding is rare, as each adult leech takes about 15ml of blood in each sitting. But in people with a clotting disorder and other health conditions, the site where the leech is applied may continue to bleed without medical intervention.

Allergies and other reactions can also occur, so leech therapy should only be administered by someone who is trained in it and is equipped to handle any adverse reactions—ideally in a hospital setting.

 

References

  1. Wei Shi, Yongxiang Xie, Liping Xie, Fang Lan, Chunli Long, Lifeng Meng and Jie Zhao. Study on protein differential expression and pathological mechanism of IgA nephropathy treated by leeches. International Journal of Clinical and Experimental Medicine, August 2019; 12(8): 9908-9916.
  2. US Food & Drug Administration [Internet]. Product classification: Leeches, medicinal.
  3. Müller C., Lukas P., Böhmert M. and Hildebrandt J.P. Hirudin or hirudin‐like factor ‐ that is the question: insights from the analyses of natural and synthetic HLF variants. FEBS Letters, 16 November 2019; 594: 841-850.
  4. Fei Deng, Jingwei Zhang, Yi Li, Wei Wang, Daqing Hong, Guisen Li & Jing Feng. Hirudin ameliorates immunoglobulin A nephropathy by inhibition of fibrosis and inflammatory response. Renal Failure, March 2019; 41(1): 104-112.
  5. Jha K., Garg A., Narang R., Das S. Hirudotherapy in medicine and dentistry. Journal of Clinical and Diagnostic Research, December 2015; 9(12): ZE05-7. PMID: 26817000.
  6. Rai P.K., Singh A.K., Singh O.P., Rai N.P., Dwivedi A.K. Efficacy of leech therapy in the management of osteoarthritis (Sandhivata). Ayu, April 2011; 32(2): 213-7. PMID: 22408305.
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