This document provides an overview of epidemiology including: - A brief history of epidemiology from ancient times to the modern era - Definitions and principles of epidemiology including the epidemiologic triad and models like exposure-outcome - Research methods used in epidemiology like observational and experimental designs - The utilization of epidemiology for disease surveillance and evaluating preventive measures - Relationships between epidemiology and other fields like clinical medicine, statistics and basic sciences

2. Introduction of Epidemiology Weiqing Chen PhD Prof. Department of Biostatistics and Epidemiology Tel: 87332199 E-mail: [email_address]

13. Snow’s Original Map of Cholera cases in Proximity to the Broad Street water pump

21. Su Delong （ 1906 ～ 1985 ） : modern epidemiologist in China. He conducted a lots of studies on schistosome and cholera. He suggested that liver cancer was associated with quality of drink water.

22. Part Two: Definition of Epidemiology

29. Part Three: Principle and Utilization

32. Host, Agent, Environment Population Environment Host Agent

33. Host, Agent, Environment

36. Exposure - Outcome Model Simple Model Complicated Model Exposure Outcome Exposure Outcome Confounder(s)

37. Spectrum of Disease Healthy Disease Onset Symptoms Seek Care Diagnosis Treatment Outcome Cure Control Disability Death

38. Infectious Disease Epidemiology Conceptual Model Uninfected Infected Diseased Removed Mediators of Infection Environment Non-immune defenses Genetic susceptibility Previous immunity Pathogen virulence Mediators of Disease Host immunity Pathogen virulence Medical intervention

39. Principle of disease and health distribution in population “ Iceberg” concept

44. Part Four: Utilization

47. Part Five: Epidemiologic methods

50. Part Five: Traits of Epidemiology

52. Part Six: Epidemiology: Future

57. Part Eight: Why do Medical students study Epidemiology?