Molecular epidemiological investigation of measles outbreaks can document the interruption of endemic measles transmission and is useful for establishing and clarifying epidemiological links between cases in geographically distinct clusters. Ter Meulen V, Wild TF, Rima BK: Identification of several different lineages of measles virus. New York: Oxford University Press; 2001:148. The Merriam-Webster’s dictionary defines epidemiology as a branch of medical science that deals with the incidence, distribution, and control of a disease in a population. New York: Oxford University Press, 2001:62.). New York, NY: Oxford University Press; 2001. According to the textbook Epidemiology 4th edition, it is the study of how disease is distributed in populations and the factors that influence or determine this distribution (Gordis, 2009). Last JM, Spasoff RA, Harris SS, Thuriaux MC, Anderson JB: A dictionary of Epidemiology. New York, Oxford University Press; 2001. Last JM: A Dictionary of Epidemiology. Epidemiologists produce data for decision-making and for understanding disease in the population. Next question, what do epidemiologists seek to do? Berdasarkan buku yang saya baca, bahwa “The core science of Public Health is Epidemiology” merupakan ungkapan yang diungkapkan oleh seorang tokoh yang bernama Gerstman pada tahun 1998. By Leon Gordis, MD, MPH, DrPH He introduces the basic principles and concepts of epidemiology in clear, concise writing and his inimitable style.