Blood suckers. Parasites. Ten stomachs. Thirty two brains. Three sets of jaws. Three hundred teeth…
Hard to like based on those features?
Yet those very features have led to an important role in the history of medicine. It continues today in the recovery process after plastic surgery and in the dispersal of blood clots.
The Ancient Egyptians, Greeks and Romans used them. Galen, a Roman doctor, believed that humans became sick as a result of what he called the Four Humours being out of balance. Blood was the dominant humour and the one needing to be kept under strictest control.
Leech therapy reached a frenzy of popularity in the 19th century. England imported 6 million leeches a year from France as demand became too great for domestic leech farms to meet.
In the 1930’s, as the use of antibiotics became widespread, they fell out of favour, but are now enjoying a revival as medical helpers.
As the leech attaches to the skin, it injects a mild anaesthetic into the wound, so the host can’t feel it. Once fed, (leeches can swell up to 4 or 5 times in size), the jaws release, and an anti-coagulant is injected to keep the blood flowing. This anti-coagulant is what disperses blood clots.
It also reduces swelling around the site of reattached limbs, for example, fingers, and keeps the dozens of minute blood vessels open. This increases the chances of a successful outcome to the surgery as blocked blood vessels could lead to infection, and rejection of the limb.
Breeding of medicinal leeches is a complex and lengthy process. They can only be used once but their impact is lasting and life-enhancing.
Still hard to like them? Try. One day those three hundred teeth could be helping to save your life.
Article created for our Historic Life weekend: Medieval Medicine and beyond on Saturday, 25 and Sunday, 26 May 2019.