Of the 400 species known to science, only one species of medicinal leech (Hirudo medicinalis) and three of its subspecies are beneficial to humans. These leeches were used to alleviate the condition of patients and to prevent diseases already in the XIV century BC. There have been ups and downs in the history of hirudotherapy. The heyday of this method of treatment can be considered the 18th-19th centuries. Then leeches in the export of Russia occupied a place on a par with grain, being an important source of income for the state treasury. And women of fashion, getting ready for the ball, put leeches behind their ears for the appearance of a delicate blush on the cheeks and to give a special shine to the eyes, while dancing until the morning was not so tiring. At the beginning of the 19th century, the leech occupied the “red corner of the pharmacy”. This method was most popular in France: from the records of Napoleon it is known that 6 million leeches were imported from Hungary alone during the year to treat the soldiers of his army. The Russian barbers masterfully mastered the methods of leeches, saving the merchant who had walked well the day before with just a couple of leeches behind his ears. Surgeon NI Pirogov, when summarizing the observations of military field practice during the Crimean War and the Caucasian expedition, noted: “I put from 100 to 200 leeches. Even in simple fractures, where only an insignificant tumor was noted, leeches were immediately placed. The circle of diseases where hirudotherapy is successfully used includes diseases of the cardiovascular system (hypertension, angina pectoris, heart failure), lungs (bronchitis, bronchial asthma), stomach (ulcer, gastritis), liver (hepatitis, cirrhosis), surgical diseases ( furunculosis, abscesses, varicose veins, thrombophlebitis, trophic ulcers and wounds, acute mastitis, the consequences of trauma). The use of hirudotherapy turned out to be effective in the treatment of gynecological diseases, in urology, ophthalmology (glaucoma), in inflammation of the paranasal sinuses, ear, etc.
The extract from the body of a leech, obtained in 1884, called hirudin, served as a starting material for the isolation and study of biologically active substances entering the blood of the body when using leeches. Previously, it was believed that the treatment occurs mainly due to the fact that the leech sucks "bad blood". Indeed, the leech sucks out 3 to 5 cubic centimeters of blood. The effect of bloodletting, for example, in high blood pressure, is a well-known and useful thing. However, the main thing, as studies have shown, is the composition of leech saliva, which is absorbed by the tissues of the body. It is believed that its constituents have been studied in general, but a number of substances introduced by leech saliva still require decoding. A medicinal leech injects over 100 bioactive drugs into the body in one session. They have an anti-inflammatory effect, activate local capillary blood circulation, improve the supply of oxygen and nutrients to tissues, prevent blood clots and dissolve fresh blood clots. Clinically, this is expressed in the rapid disappearance of heart pains, elimination of edema, restoration of impaired blood circulation in the brain and other organs. There is every reason to call a leech a mini pharmaceutical factory. The most important enzyme of the leech secretion is hyaluronidase - a vector with the help of which all other biologically active substances that make up the secretion are absorbed by the body, penetrating into tissues to a depth of 10 centimeters. Thus, the therapeutic effect is achieved not by suction, but, on the contrary, by injection.