[SOUND] Hello, in this week's lectures, we'll discuss what epidemiology is, the history of epidemiology, and the different public health perspectives. >> In order to orient you to the course, we will provide a course map at the beginning of each week's lectures. This week is module one and we will be covering an explanation of what epidemiology is. And the population perspective of epidemiology. After you have reviewed all of week one lectures, you should be able to complete these learning objectives. They include define epidemiology. List the uses of epidemiology in public health. Describe how epidemiology supports improving the public's health. Characterize two perspectives on health outcomes in populations, the biomedical perspective, and the population perspective. Relate the mission of public health, to the population perspective on health outcomes in populations. Describe the historic development of epidemiology. And apply the population perspective to an understanding of the global burden of health outcomes and disease. Epidemiology is the study of the distribution of health outcomes or disease within populations. And the factors that determine the spread of health outcomes and diseases. These factors that determine whether someone gets a certain health outcome or disease are called risk factors. Epidemiologists, focus their attention at the population level rather than the individual level. In order to understand an epidemiology, it is first helpful to review some of the basic history of the field. People have long viewed epidemics of disease, and plagues as terrifying occurrences. There has been a continued desire to have a more rational, and complete way to explain diseases. And more recently, other health outcomes rather than believing that diseases were simply caused by spirits or a God. Empirical observations of epidemics and other causes of mortality, were the beginning of the field of epidemiology. Epidemiology's focus was initially on infectious diseases, until early in the 20th century. Towards the end of the 20th century, computers, increasing information technology, and new methodological approaches altered the field of epidemiology. Epidemiology has become a standard area of clinical science, and is the most fundamental basic science of public health. Over time, the definition and focus of epidemiology has changed. The focus was just on infectious diseases and epidemics in the mid 1800s. Epidemiology began to focus on infectious disease overall in the mid 1900s. By the mid 1950's epidemiology's focus then included not just infectious diseases, but specific conditions associated with them. In the 1960's epidemiology began to focus on laws regarding the distribution of disease at a community level. Then, in the late 1980's, epidemiology focused on how to control or minimize health problems and diseases. Next, we will talk about epidemiologic transitions. An epidemiologic transition describes changing patterns of population age distributions, mortality, fertility, life expectancy, and causes of death. The human population has gone through four major disease transitions since the agricultural period began. The first transition is related to the emergence of infectious diseases and diseases related to nutrition. And to the beginning of the practice of agriculture and food production. 10,000 years ago, people became less dependent on hunting and gathering once they were able to produce food and domesticate animals. This shift led to zoonotic disease, nutrient deficiencies, and increased contact with disease vectors during agricultural activities. The second transition was a time where human immune systems and disease-causing organisms both evolved, resulting in a change from major epidemics of disease to endemic disease. People developed physical and genetic changes that serve to minimize the effects of diseases. The third transition resulted when disease patterns changed from infectious to chronic and degenerative diseases, in developed parts of the world due to improvements in nutrition, public health, and clinical medicine. Cardiovascular diseases and cancer began to occur more during this transition. They are often associated with the longer lifespan and a sedentary lifestyle. The fourth transition started at the end of the 20th century. When both new diseases and the reemergence of infectious ones occurred as well as the rapid spread of disease due to globalization. So let's compare the four epidemiologic transitions. The first transition started when hunter gatherers began to practice agriculture and began to live in one place. There was a transition from few epidemics to major epidemics. The second transition happened because populations developed immunologic resistance and disease-causing organisms changed. There was a transition from major epidemics of disease to endemic diseases. The third transition came from improved public health and sanitation. There was a transition from infectious diseases to non-infectious chronic and degenerative diseases. The fourth transition was due to increased globalization. There was a resurgence and rapid spread of infectious diseases. This concludes the first part of this lecture on the history of epidemiology. Please continue on to the next part, where I will discuss some pioneers in the field of epidemiology.
