The image above illustrates the ten essential functions of public health. Epidemiology plays a particularly important role for three of the functions: monitoring, investigating, and evaluating. The 10 Essential Public Health Services describe the public health activities that all communities should undertake. Public health systems should
- Monitor health status to identify and solve community health problems.
- Diagnose and investigate health problems and health hazards in the community.
- Inform, educate, and empower people about health issues.
- Mobilize community partnerships and action to identify and solve health problems.
- Develop policies and plans that support individual and community health efforts.
- Enforce laws and regulations that protect health and ensure safety.
- Link people to needed personal health services and assure the provision of health care when otherwise unavailable.
- Assure competent public and personal health care workforce.
- Evaluate effectiveness, accessibility, and quality of personal and population-based health services.
- Research for new insights and innovative solutions to health problems.
Disease surveillance systems and health data sources provide the raw information necessary to monitor trends in health and disease. Descriptive epidemiology provides a way of organizing and analyzing these data in order to understand variations in disease frequency geographically and over time, and how disease (or health) varies among people based on a host of personal characteristics (person, place, and time). This makes it possible to identify trends in health and disease and also provides a means of planning resources for populations. In addition, descriptive epidemiology is important for generating hypotheses (possible explanations) about the determinants of health and disease. By generating hypotheses, descriptive epidemiology also provides the starting point for analytic epidemiology, which formally tests associations between potential determinants and health or disease outcomes. Specific tasks of descriptive epidemiology are the following:
- Monitoring and reporting on the health status and health related behaviors in populations
- Identifying emerging health problems
- Alerting us to potential threats from bioterrorism
- Establishing public health priorities for a population
- Evaluating the effectiveness of intervention programs and
- Exploring potential associations between "risk factors" and health outcomes in order to generate hypotheses about the determinants of disease.
After successfully completing this unit, the student will be able to:
- Explain the role of descriptive studies for identifying problems and establishing hypotheses.
- Explain how the characteristics of person, place, & time are used to formulate hypotheses in acute disease outbreaks and in studies of chronic diseases.
- Identify case reports and case series and explain their uses and their limitations.
- Describe the design features of an ecologic study and discuss their strengths and weaknesses.
- Explain the concept of ecologic fallacy both in general and in the context of a study. Identify the strengths and limitations of an ecologic study.
- Describe the design features of a cross-sectional study and describe their uses, strengths, and limitations.