The leech in the Bible

 “The leech has two daughters. ‘Give! Give!’ they cry. Proverbs 30:15

The Hebrew word aluqah comes from a verb which means “to suck”, and refers to the organism which we refer to as the leech. It was translated into Greek as bdella and into the Latin Vulgate version as sanguisuga, which is leech in English.

It is only mentioned once in the Bible, in the book of Proverbs, and probably refers to the species commonly known as the horse leech (Haemopsis sanguisuga), which is very large in size and very common in Israel and the Middle East. This generic name (Haemopsis) means “the act of drinking blood” as this insatiable creature is capable of continuously sucking up to 16 grammes of human blood. Although its common name is “horse leech”, it poses no threat whatsoever to this animal, or to almost any other mammal, as its jaws are too small to perforate their thick skin.

It habitually feeds on the larvae of insects, small fish, amphibians and snails which it tracks down chemically by means of the traces they leave in the water. Its colour varies from green to dark brown or slate-grey, and it can reach a length of up to 15 centimetres.

Leeches are a species of worms belonging to the annelid family, like earth-worms. But they differ from the latter in that they have two suckers, one at each end of their body. More than 600 subspecies have been clearly identified, although only 15 of them have been used for medicinal purposes. The best known of the latter is the Hirudo medicinalis, or the medicinal leech.

They used to be used in medicine as it was believed that certain diseases could be cured by the extraction of blood. Their use for this purpose in medicine dates back to more than 3000 years ago. In 1833, France imported more than 40 million leeches to cure conditions such as delirium tremens, mental illness, certain skin diseases, tumours, whooping cough, gout, obesity, among many others, procedures which might well make us laugh now, but which, before the discovery of antibiotics, were taken very seriously. Hence it should come as no surprise that in the 19^th century surgeons were nicknamed after them: leeches!

Treatments with leeches are in fact still recommended by many practitioners of natural medicine, especially to treat arthritis and certain inflammations, among other ailments, both in animals and human beings.

Most species of leech are freshwater organisms, although there are also some marine and terrestrial species. They swim by undulating their bodies, or by using their suckers to drag themselves along the surface. Many live parasitically on the bodies of fish, amphibians or mammals, and some have been known to attack human beings. They attach themselves to the skin and make a small Y-shaped incision in the skin with their sharp jaws. Then they inject their saliva, which contains an anaesthetic substance, another substance which prevents the blood from clotting and a third which causes the blood vessels to dilate. In this way, certain species of leech are capable of sucking an amount of blood equivalent to ten times their weight.

Nevertheless, the main danger posed by the leech’s bite is not the loss of blood but the bacterial infection that it can cause. One of the risks of drinking water from natural springs is precisely that of accidentally swallowing one of these animals, because if they attach themselves to the mucous glands of the throat or nose, they can swell with blood and cause asphyxia or internal bleeding. In the Middle East and India many domestic animals (such as cows, horses and dogs) die every year for this reason.

Traditionally, egotistical and greedy people who gradually appropriate for themselves the possessions of other people have been called “leeches”. This is precisely the meaning given to the term in the only Biblical reference to it. Indeed, it is among the proverbs that refer to insatiable things that the leech appears, as, from the perspective of the author, it is an animal that never has enough. It would seem that in Hebrew the name “leech” is associated with the persistent demand: “Give me, give me”.

The Bible repeatedly condemns both greed and usury. In the book of Leviticus, God commands: “Now if your countryman becomes destitute and cannot support himself among you, then you are to help him as you would a foreigner or stranger, so that he can continue to live among you. Do not take any interest or profit from him, but fear your God, that your countryman may live among you. You must not lend him your silver at interest or sell him your food for profit. (Lev. 25 v 35-37).

And in Proverbs 28:8 we read: “He who increases his wealth by interest and usury lays it up for one who is kind to the poor.” So according to Scripture the righteous person distinguishes themselves from others by the fact that they do not speculate with or take advantage of the need of others. That is to say, they do not act like leeches.

Antonio Cruz, biologist and theologian.