For millennia, one of the main medicines used in the world was a worm capable of sucking people’s blood. Craziness? It may be, but after falling into ostracism in the 20th century, the leech, believe it or not, has been «prescribed» again by several doctors. This strange parasite, found in fresh water and resembling a very dark slug, began to be used in India around 2,500 years ago. It did not take long for it to become successful in ancient Greece as well and spread throughout the West. It was then believed that illnesses, from a headache to hemorrhoids, were caused by problems in blood concentration, which could be solved with a simple bloodletting. As the specialty of this worm is precisely to suck the blood of its hosts without causing discomfort, the treatment became popular. This belief went through the Middle Ages and reached the 19th century, when hospitals in Paris used up to 6 million leeches to remove 300,000 liters of blood per year from patients!
In the middle of the 20th century, bleeding was abandoned due to the lack of proof of its effectiveness. In the last five years, however, leeches have returned to the scene in the United States and Europe, proving to be useful in the postoperative period of patients who have had limbs reimplanted. It’s just that they help to restore blood circulation between the reconstituted tissues, because, by sucking the blood, they encourage the formation of new veins – which are difficult to reconnect in surgeries because they are thin.
The technique did not reach Brazil because the European species of the animal, Hirudo medicinalis, is not found here. “The Brazilian species don’t feed out of the water, so they aren’t suitable for surgical use”, says biologist Fernanda Faria, from the Butantan Institute, in São Paulo. But in the United States it has been so successful that even a machine that replaces the worm is being tested. After all, many patients do not like to see, in the 21st century, a doctor taking half a dozen leeches from an aquarium to use in the postoperative period.
1. The leech has suckers at both ends of the body that allow it to stick to its victim. With her sharp teeth, she takes a bite that is completely painless, as it is accompanied by a natural anesthetic.
2. On the person’s skin, there is the mark of the incision made by the leech. Her saliva has anticoagulant substances that prevent healing and make the victim’s blood flow freely. The worm can suck in the equivalent of ten times its body weight (or 150 milliliters of blood), growing enormously in length to take in all that food.
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