Abstract
Epidemic diseases, known and studied in China since antiquity, are one of the main chapters of the School of Exogenous Febrile Diseases (). Along with the legends about epidemic demons, China has developed over the centuries a medical approach based on the teachings of Huang Di Nei Jing (Internal Classic), Nan Jing (Classic of Difficulties), and Shang Han Lun (Treatise of Harmful Cold). However, it was in the 17(th) century, after the great break of the Song, Jin, and Yuan eras that an innovative spirit Wu Youxing () first foresaw the existence of microorganisms as we know them now. His Wen Yi Lun (Treatise on Pestilences) foreshadows an original approach to epidemic diseases, particularly emerging infectious diseases of the 21(st) century: severe acute respiratory syndrome 2003-2004 and the COVID-19 pandemic are perfect examples. In this first article, which will be followed by two others, we will examine the classical and modern Chinese definitions of these dreadful plagues.