The goal of this textbook is to explain the general principle of infectious diseases and the most common infectious diseases, including etiology, epidemiology, pathogenesis and pathology, clinical manifestations, laboratory examinations, diagnosis,differential diagnosis, prognosis, treatment and prophylaxis. At the same time itpresents a thorough and updated overview of this field. Emerging and reemerging infectious diseases are also included in it, like SARS, H1N1 and hand-food-and-mouth diseases. To aid students comprehension, a couple of questions are included at the back of each section.