E. Wittke-Michalsen

Leeching is one of the most ancient healing methods documented in the history of medicine. The first clearly identifiable account of leeching appears in ancient Sanskrit writings from India. According to Hindu mythology, Dhavantari, the physician who revealed the secrets of traditional Indian medicine to the world, held nectar in one hand and a leech in the other. The most extensive descriptions of leeching in the Indian literature appear in the writings of the physician Sushruta (100–600 B.C.E.). Leeching was also an ever-present force in traditional Chinese medicine (TCM), but was of lesser significance than in Indian medicine.

In Europe, medicinal leeching was viewed as a science-based therapeutic method right from the beginning. Leeching was an integral part of conventional and folk medicine from antiquity to the 19th century. Medicinal leeching initially remained primarily the domain of empirically minded physicians. Then, most proponents of medicinal leeching deduced its therapeutic efficacy within the framework of the prevailing scientific paradigms of their respective school of medicine. Leeching remained part of various systems of medicine through the centuries. The underlying basis for its use was the widespread belief in the concept of body humors (humoral pathology). This broad concept of disease was based on the notion that all illnesses are caused by an imbalance of one of the four body fluids, or humors (blood, phlegm, yellow bile, and black bile).

In most cases, it is not possible to reliably and accurately translate the historical classification of diseases, their underlying causes within the body, and the corresponding indications for treatment as defined by humoral pathology into the language of modern medicine. Basically, the historical definitions of disease types, constitutional causes, and treatments established based on the humoral concept of disease should be taken metaphorically, similar to the concepts of TCM and Indian medicine that are still present today.

The first detailed description of the therapeutic use of leeches in ancient Greek medicine, which was influenced by Indian medicine, can be found in the poem Alexipharmacia by Nicandros of Colophon (200–130 B.C.E.). However, medicinal leeching first gained true significance in the Methodist School, which differentiated two main causes of disease, e. g. “constriction” and “dilation.” Chronic headache, general febrile conditions, psychoses, epilepsy, ear ailments, liver disease, splenic and intestinal disorders, ischialgia, arthritis, and gout were the main indications for medicinal leeching; general diseases causing symptoms of hardening, heaviness, rigidity, tension, swelling, pain, and cramps (referred to as “status strictus” in the ancient nomenclature) were additional indications. Leeches were regarded primarily as tools for alleviating the tension associated with status strictus.

Leeching played a less important role than venesection and cupping in medieval Arabic medicine, where leeches were typically used to treat a variety of skin diseases and illnesses associated with the melancholic temperament (black bile). In Italy, on the other hand, physicians from the school of Salerno used leeches to remove excess body fluids in numerous indications. The teachings of Salernitan physicians gradually spread from Italy across all of Europe.

In the late age of Galenism, medieval physicians also used leeches primarily for “derivation” and removal of harmful fluids directly from an afflicted body part. They believed that the elimination of fluids by leeches promoted “internal combustion” (complete combustion of a body substance by natural organ heat) of residual disease material, thereby promoting natural healing. Leeching, as a simple systemic method for eliminating fluids, was indicated for treating conditions characterized by a general overabundance of fluids (e.g., fever) and could be used instead of venesection. The most important late-Galenic proponent of leeching was Abraham Zacuto (1575–1642), who expanded the range of indications for leeching and established the empirical basis for many physicians of the following years.