Public health nursing allows nurses to encounter various vulnerable populations on a daily basis. In particular, the elderly make up a large portion of the population, and their vulnerability to the environment and other physical factors is a very important aspect of public health nursing. Epidemiology allows the public health nurse to study and assess vulnerable populations, including the elderly, and create interventions that maximize the health potential of all members of the public. Definition and Description of Epidemiology
Originally, epidemiology was a term that was used to describe the spread of infectious disease. Over the course of time, that definition has expanded considerably in order to accommodate the complexity of ever-changing populations, their environments, and increasing occurrences of disease. Epidemiology is now defined as the multidisciplinary study of various states of health, causal factors, how these states of health are dispersed across a population, and ways in which the knowledge gained from these studies can be used to promote health and wellness for the entire population (Stanhope & Lancaster, 2012). By using the scientific method of investigation, health care professionals, including public health nurses, are able to identify the various health needs found within communities and design interventions that specifically target meeting those health needs. Due to close contact with the community, public and community health nurses have an advantage with being able to identify local disease patterns and specific cases, as well as offer education designed to prevent or control specific diseases based on risk factors and other environmental factors (Wissman, 2007). With the predicted growth of the older adult population in the United States, the study of the elderly population is especially important within the realm of epidemiology. The elderly population makes up the fastest growing portion of the population (Stanley, Blair, & Beare, 2005) . It is estimated that there will be more than 50 million people over the age of 65 living in the United States by the year 2020 (Abrams, Beers, & Beckow, 2000) . Results from the 2010 census taken in the United States reflects that elderly people, or people over the age of 65, make up 12.7 percent of the total population (United States Census Bureau, 2012) .With cultural diversity also growing at rapid rates, and new health concerns always on the horizon, epidemiology, especially related to the elder population, becomes critically important (Stanley, Blair, & Beare, 2005). Steps and Methods Used in Epidemiology
The epidemiological process is complex and consists of many steps. The first step is to identify the health related problem and determine its significance. At this stage, the public health nurse gathers data from all available sources and then uses that data to determine the range of the problem. The next step in the process is to develop a theory exploring possible explanations based on the data that has been compiled. From this point, information is sorted and narrowed down, and the validity of the hypothetical possibilities is explored further. The fourth step involves developing a plan designed to control or put an end to the disease process that is being evaluated. During this phase, all influential factors related to the spread of disease are identified and evaluated, and prioritized goals are created in order to halt the sequence of the spread of disease. The fifth step in the process is putting the plan into action by using all available resources. From there, relevant information is obtained in order to evaluate the effectiveness of the plan in preventing the spread of disease. The seventh and final step consists of creating a report of pertinent data, including evaluation of accomplishments and failures, and basing follow-up recommendations and interventions on this information...