Above: Image © Bobjgalindo, Wikimedia
This article was reviewed and updated by the CurioCity team in September 2017.

What is slimy, has three jaws and about 300 teeth, and likes to suck on your scrumptious human blood?

As weird as it may sound, leeches have long been known to have useful medicinal properties. From the ancient times until the 19th century, leeches were commonly used for bloodletting, a procedure that medical professionals thought could help treat all kinds of ailments.

Did you know? The word leech is an archaic English word for doctor!

Eventually, doctors stopped using bloodletting practices because bloodletting didn’t have a scientific basis.  In recent years, however, leeches have been making a medical comeback.

The U.S. Food and Drug Administration classified leeches as live medical devices in 2004. They were the second creepy-crawly to get this designation.

Did you know? The first creepy-crawly to get designated as a live medical device was the maggot.

Leeches in reconstructive surgery

Leeches have numerous helpful uses in medicine. Reconstructive surgery, surgery to improve the form or function of a body part, is the most common use for leeches. When a body part is reattached, it is difficult to realign the blood vessels (the plumbing). This may result in blood pooling at the reattached tissue. Pooling blood is a big problem because it results in blood clots, which prevents the return of oxygen and nutrients to the tissue. This is where “doctor leech” arrives to save the day.

Leech saliva contains several helpful compounds in their saliva, which helps the wound healing process. For example, leech saliva contains:

  1. A powerful anticoagulant, which prevents clotting. This is important to ensure blood can continue to flow into the reattached tissue.
  2. A vasodilator, which dilates blood vessels to improve blood flow. This helps increase the amount of oxygen and nutrients available to the reattached tissue.
  3. An antibiotic, which helps to prevent infection of the surrounding tissue.
  4. A local anesthetic, which makes the leech bite painless.

Together, these properties of leech saliva help to save tissue that normally would die.

Other leech treatments

But Doctor Leech doesn't just stop there. Scientists are currently investigating leeches as treatment for osteoarthritis (degeneration of the joints). Experiments with leeches have shown that attaching these beasts to your knees helps with osteoarthritis pain, and improves mobility.

On top of that, hirudin, the anticoagulant component of leech saliva, is currently being used as a drug to prevent heart attacks.

Leeches may seem slimy and gross, but as the old saying goes,  “Don't judge a book by its cover!” Many leeches end up giving their lives for humankind. Once a medicinal leech has finished eating its fair share of yummy blood, it meets a tranquil end in a pickle jar to prevent the spread of bloodborne diseases.

This article is based on an article written and researched by Tony Lim. Following in Doctor Leech's footsteps, Tony has worked  on understanding how local anesthetic drugs help people who have chronic pain.

Learn more!

Tony Lim

I am a graduate student pursuing a PhD in the neuroscience program at McGill University. In addition to neuroscience, my scientific interest and background lies in the field of pharmacology. When not at the lab, I enjoy playing volleyball, badminton, snowboarding and playing electric guitar with the band in my spare time.

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