What is epidemiology?Epidemiology is the foundation of public health and is defined as the study of the “distribution and determinants(link is external and opens in a new window)” of diseases or disorders within groups of people, and the development of knowledge on how to prevent and control them. Epidemiological research helps us understand not only who has a disorder or disease but why and how it was brought to this individual or region.One of the earliest instances of modern epidemiology can be found during an 1854 cholera outbreak in London(link is external and opens in a new window). Doctors believed the widespread illness must have been airborne, but Dr. John Snow, widely considered to be the father of epidemiology, employed a different kind of thinking. By carefully mapping the outbreak and analyzing those who were infected, Snow was able to link every cholera case to a single water pump at the intersection of Broad and Cambridge Streets (now Lexington Street) in London’s Soho neighborhood. The removal of the pump stopped the disease in its tracks—laying the basis of today’s epidemiological practices.