The plague epidemic in the late Middle Ages had a drastic impact on the demographic and societal development in Europe. The medieval perception of the plague considered several causes for the disease, many of them in a religious context. Other causes were presumed based on astrological constellations, weather conditions, natural phenomena or an act of God, or even the fetid odor caused by rubbish, vapors, or pestilential bubo. Signs, symptoms, and consequences of the plague were known and therefore greatly feared. In this historical context, different solutions and recommendations were developed in order to prevent an infection with the plague but also to ease its symptoms. Only when the bacterium Yersinia pestis was discovered in 1894, the plague epidemic could be understood in connection with unsanitary conditions and transmission routes by means of fleas and rodents (especially rats). Even though the danger of a plague epidemic in Europe is almost nonexistent nowadays, the bacterium is still virulent in Africa, Asia, as well as South and Central America. Historical herbal books document a variety of apotropaic herbs against the plague, e.g. common juniper (Juniperus communis), burnet (Pimpinella saxifraga), and angelica (Angelica archangelica), as well as herbs to treat pestilential bubo (e.g. deadly nightshade (Atropa belladonna L.)). Oral and topical applications of herbs were also documented in combination with amulets, ritual fumigations, and bunches of herbs.
