Leeches and leech products are in use for medical purpose in many countries across the Indian ocean. Stories about this animal were gathered and written by students. They are all part of a pedagogical project, funded by the National University of Singapore and the Université de Paris. The Bestiary site is a work-in-progress and a participatory educational tool, representing animals whose products or body parts are used to promote health and healing.


A Story by Elizabeth Siobhan Loke Hui Zhen

Leeches have been used in the practice of medicine for centuries, as their saliva contains anti-coagulants, used to drain infected blood from patients. Today, leeches are used in hospitals for leech therapy in modern medicine to promote the healing of wounds. However, these leeches must be sterile, and disposed of immediately after use. I discuss the usage of various species of leeches – Whitemania Pigra Whitman, Hirudo nipponica Whitman and W. acranulata Whitman of family Hirudinidae – in traditional Chinese medicine (TCM). 

Leeches are interesting for their utility in both Western and Eastern medicine. While the practice of bloodletting through leeches dates back several centuries, the leech continues to be a helpful tool in modern medicine today. In TCM, leeches are also consumed, their dried bodies are ground into powder, which has various healing properties. It is used to treat cerebral hemorrhage and other thrombosis related diseases, and to dispel blood stasis and resolve stagnation and accumulation. It is believed to interact with the liver meridian, and used in tandem with other herbs in prescriptions for the aforementioned diseases. Despite its many functions, it cannot be prescribed to pregnant women because it has toxic properties, and high doses of it could affect the fetus and its development.

The human interactions with animals, even if parasites, have sometimes yielded remarkable and dependable tools for healing and medication. While there have been no confirmed cases of direct transmission of parasites between humans and leeches, some fish leeches are known to transmit parasites. Research shows that leeches could store red and white blood cells from humans containing the Human Immunodeficiency Virus (HIV) in their bodies for up to six months. This material did not transfer to the leeches saliva, which is the main point of contact between the leeches and those they feed on. Therefore, safety precautions are crucial to prevent any sort of transmission of diseases. The leeches were also shown to be hosts of various bacteria and other parasites, which is why the use of live leeches in modern hospitals is strictly regulated.

Treatment with leeches. Historical artwork of a woman using leeches to treat disease. She has taken some of the blood-sucking leeches out of a jar at left and placed them on her arm. Leeches were prescribed to treat diseases thought to be caused by the presence of too much blood in the body. While this medical theory has been disproved, leeches are sometimes used today to drain areas of partially clotted blood (haematomas) from a wound. This woodcut is from Historia Medica by W. van den Bossche, which was published in 1638.Wikimedia Commons
NEHILI, M., ILK, C., MEHLHORN, H., RUHNAU, K., DICK, W., & NJAYOU, M. (1994). “Experiments on the possible role of leeches as vectors of animal and human pathogens: A light and electron microscopy study”. Parasitology Research (1987), 80(4), 277-290. 
Leech. (n.d.). Traditional Chinese medicine wiki, (retrieved October 25, 2021). 
Kans, B. (2017, April 21). “What is leech therapy?” healthline.  
“Leech (shui zhi): What is leech? What is it used for?”. (n.d.). Acupuncture today, (retrieved October 25, 2021). 


A Story by Aishwarya Afiqah Puri Bte Mh

What is the first thing you think of when I mention leeches? Most of us would naturally equate them to disgusting, slimy blood sucking creatures that are most likely dangerous. However, contrary to popular beliefs, leeches have many benefits that many may not be aware of. The use of leeches in medicine is prominent in both early and modern times. The very first record of leeches being used as a treatment was in Sanskrit writings of the ancient Indian physicians Caraka and Suśruta, dating from the beginning of the Common Era (Editors, 2018.). The treatment of bloodletting (withdrawal of blood) was believed to help tumors and was a wide-spread treatment for a variety of illnesses (Martucci, 2020). It was only in the 20th century that leech therapy has established itself in plastic and microsurgery, as a protective tool against venous congestion and has served to salvage replanted digits and flaps (Abdualkader et al., 2013). This is due to the ability of leeches to secrete proteins that prevents blood clots. These secretions are also known as anticoagulants. This keeps blood flowing to wounds to help them heal (Wilson, 2017).

Apart from cosmetic surgery, leeches are also used in the research for cancer treatment as they have antistasin which prevents lung cancer colonization, for gangrene treatment caused by diabetes and as aids in dental surgery by decreasing inflammation. It is also used in traditional Chinese medicine (TCM) to augment blood flow to the distal parts of the body and to alleviate coagulation disorders (Abdualkader et al., 2013). The discovery of the benefits of leeches have brought unparalleled advancements in modern/western medicine.

While leeches do not carry diseases, they can cause death if the treatment is not carried out with proper care. Small, young specimens of one aquatic leech species, native to Eurasia and Africa, can parasitize both humans and animals. They enter the body either through drinking water or through the excretory openings of persons who bathe in infested waters. They can latch onto the inner trachea and cause internal bleeding. Moreover, leeches can cause an allergic infection and excessive bleeding, if they are removed forcefully and not done correctly.

Sucking leech (Hirudo medicinalis), 2011, Wikimedia Commons


Britannica, T. Editors of Encyclopaedia (2018, November 21). “leeching”. Encyclopedia Britannica

Martucci, J. (2020, March 20). “Medicinal leeches and where to find them”. Science History Institute. 

Krans, B. (2017, April 21). “What is leech therapy?” Healthline. 

Jha, K., Garg, A., Narang, R., & Das, S. (2015). “Hirudotherapy in medicine and dentistry”. Journal of Clinical and Diagnostic Research, 9(12), ZE05-ZE07. 

“Leech”. (n.d). Molecular Expressions, (retrieved October 14, 2021).

Abdualkader, A., Ghawi, A., Alaama, M., Awang, M., & Merzouk, A. (2013). “Leech therapeutic applications”. Indian Journal of Pharmaceutical Sciences, 75(2), 127-137.