Epidemiology Introduction Lecture 1

Study Notes

Lecture 1: Introduction to Epidemiology

Epidemiology is derived from Greek words:
- Epi: on or upon
- Demos: people
- Logos: study of
Epidemiology is the study of disease distribution, determinants, and application to health control.
Epidemiologists study sick people, healthy people, exposed people, and non-exposed people to define differences and causal relationships.
Uses of epidemiology include understanding the natural course of disease, planning health services, providing administrative data, determining disease causes, finding causative agents, understanding transmission, studying contributing factors, and recognizing geographic patterns.
Epidemiology aims to develop disease control measures and prevent or control disease.
Types of epidemiology:
- Descriptive epidemiology: Examining disease patterns in populations, observing basic features of distribution.
- Analytic epidemiology: Investigating hypotheses about disease causes by studying relationships between exposures and disease.
Analytical epidemiology requires information to know where to look, what to control, and develop viable hypotheses.
Descriptive studies look at three key aspects:
- Person: Age, gender, ethnicity, genetics, concurrent diseases, diet, activity, smoking, risk factors, socioeconomic status (SES), education, occupation.
- Place: Presence of agents/vectors, climate, geology, population density, economic development, nutritional practices, and medical practices.
- Time: Calendar time, time since event, physiologic cycles (age), seasonality, and temporal trends (changes over time).
The Epidemiologic Triangle: a model featuring:
- Agent: Factors that can cause disease: includes biological (bacteria, viruses, parasites), physical (trauma, radiation, burns), and chemical (alcohol, poison, smoke) also pathogenicity and dose.
- Host: The human who can get the disease: influenced by personal traits, behaviors, genetics, and immunologic factors.
- Environment: Extrinsic factors that affect agent and exposure opportunity, such as external conditions, and physical, biological, and social factors that contribute to the disease process.