Chapter 14 Epidemiology and Urban Health Research Sandro Galea and David Vlahov 1.0. WHAT IS EPIDEMIOLOGY AND WHAT ROLE CAN IT PLAY IN URBAN HEALTH RESEARCH? “Epidemiology” is derived from the Medieval Latin term “epidemia,” meaning an epi- demic, and reflects the origins of epidemiology as the discipline concerned with tracking and controlling disease epidemics. Modern epidemiology has expanded its scope and many definitions for epidemiology have been suggested, some at odds with one another (Swinton, 2004). Most epidemiologists might characterize their discipline as the study of the distribution of disease and of the causes (or determi- nants) of that distribution (Lilienfeld, 1978). Congruent with this definition, the American Heritage Dictionary defines epidemiology as “The branch of medicine that deals with the study of the causes, distribution, and control of disease in popu- lations” (American Heritage Dictionary, 2000). Therefore epidemiology provides the empiric tools that inform both medicine and public health and epidemiologic method are critical to the study of disease distribution, cause, and subsequently control. Broadly speaking, we can think of two principal roles for epidemiology. First is a descriptive role, often referred to as disease surveillance. Here epidemiology helps to describe the frequency of disease, both overall, but also in different groups, including, for example, gender, race/ethnicity, geographic groups, or over time. Description of disease is a critical function epidemiology plays to inform public health policy and practice. For example, the recent documentation of the growing prevalence of obesity throughout the U.S. has fuelled national interest in the obe- sity epidemic and the development of national and regional initiatives aimed at reducing obesity and associated morbidity (Katz, 2003; Wang, et al., 2002). In local public health departments, epidemiologic surveillance of infectious diseases serves to identify infectious disease outbreaks, a core function of both local and federal public health agencies. 259 Ch14.qxd 4/22/05 2:16 AM Page 259