Descriptions of intestinal worms in European medieval medical texts

This article investigates medieval medical texts to discover what they have to say about parasites. The principal focus is on intestinal worms found in <i>practica</i> texts written from the 11th to the 15th centuries in Latin in Western Europe. <i>Practica</i> texts deal with illnesses of the human body from head to heel. The chapters on worms occur in discussion of illnesses of the intestines. These <i>practica</i> texts were used in medical education in universities as well as guiding medical practice. Islamicate writings translated from Arabic into Latin influenced western ideas about intestinal worms. <i>Practica</i> texts identify 3 or 4 kinds of intestinal worm depending on size and shape. They are thought to be generated in different parts of the intestine and rectum. Worms are made from matter associated with the humour phlegm which is cold and wet and putrefaction within the body gives life to them. Other parasites of the human body are found close to the skin surface but resemble intestinal worms in the ways they are generated. Areas of argument and dispute arose in learned medical literature. These arguments did not introduce new concepts or research findings but built on analysis of the doctrines of ancient and Islamicate writers. While humoral imbalance is understood to cause worms, recipes from the treatment section usually emphasize the aim of killing and expelling the worms from the body using bitter ingredients like <i>Absinthium</i> (wormwood).