The study of the distribution and determinants of health-related states or events in specified populations, and the application of this study to the prevention and control of health problems
Fields that epidemiology makes use of
Biology
Sociology
Demography
Geography
Environmental science
Policy analysis
Statistics
Components of epidemiology
Studies of disease frequency
Studies of the disease distribution
Studies of determinants of disease
Study
Includes surveillance, observation, hypothesis testing, analytic research, experiments
Distribution
Refers to analysis by time, places, classes of people affected
Determinants
Include all factors that influence health: biological, chemical, physical, social, cultural, economic, genetic, behavioral
Health-related states or events
Refer to diseases, causes of death, behaviors, positive health states, reactions to preventive regimens, provision and use of health services
Specified populations
Include those with identifiable characteristics such as occupational groups
Cases
People afflicted with a disease, the number of people diagnosed with the illness
Epidemic
An unexpectedly large number of cases of a disease in a particular population, disease occurrence above normal expectancy
Endemic
A disease that occurs regularly in a population as a matter of course, normally prevails in the community
Hyperendemic
Persistent, high levels of disease occurrence, a situation where there is a persistent and consistently high level of disease occurrence
Pandemic
An outbreak of disease over a wide geographical area such as a continent, the global spread of disease affecting large populations
Sporadic disease
Few scattered cases, a disease that occurs infrequently and in isolated or scattered cases
Epidemic
10 cases of legionellosis occurred within 3 weeks among residents of a particular neighborhood (usually 0 or 1 per year)
Hyperendemic
The average annual incidence was 364 cases of pulmonary tuberculosis per 100,000 population in one area, compared with the national average of 134 cases
Pandemic
Over 20 million people worldwide died from influenza in 1918-1919
Sporadic
A single case of histoplasmosis was diagnosed in a community
Endemic
About 60 cases of gonorrhea are usually reported in this region per week, slightly less than the national average
Practical applications of epidemiology
Assessment of the health status of the community
Elucidation of the natural history of disease
Determination of disease causation
Prevention and control of disease
Monitoring and evaluation of health interventions
Provision of evidence for policy formulation
Disease
An abnormal condition of an organism or part, especially resulting from an infection, inherent weakness, or environmental stress that impairs normal physiological functioning
Disease
The outcome variable (dependent variable)
Exposure
A catch-all term for agents, interventions, conditions, policies, anything that might affect health, the predictor or explanatory variable (independent variable)
Studies of disease frequency
Measurement of the frequency of disease, disability, death, helps in understanding the burden of these health outcomes and provides information for public health planning
Prevalence
The proportion of individuals in a population who have a particular disease or condition at a specific point in time, gives an estimate of the total number of existing cases
Incidence
The rate at which new cases of a disease occur within a population during a specified time period, provides insights into the risk of developing the disease
Studies of the disease distribution
Characterize who, where, or when in relation to what (outcome), helps identify patterns and risk factors associated with the disease
Descriptive epidemiology
The branch of epidemiology that aims to describe and summarize disease patterns and characteristics, provides a foundation for generating hypotheses
Studies of determinants of disease
Test hypotheses about the causes and risk factors of a disease, provide insights into the underlying reasons and mechanisms behind the occurrence of a disease
Analytical epidemiology
The branch of epidemiology that focuses on analyzing and interpreting data to assess the associations between potential determinants and disease outcomes
Areas of concern of epidemiology
Describing the distribution of disease
Interpretation of the distribution of the disease in terms of possible etiologic agents or causal factors
Epidemiologists investigate and identify the origin of the source of an epidemic
Analytical epidemiology
Provides crucial evidence for the development of effective health programs, interventions, and policies
Findings from analytical epidemiology
Help inform strategies for the prevention, control, and management of the disease, leading to improved public health outcomes
Areas of Concern of Epidemiology
Describing the distribution of disease in terms of sex, age, race, geography, etc.
Interpretation of the distribution of the disease in terms of possible etiologic agents of causal factors
Scope of Epidemiology
To trace the source of the epidemic
Limit the spread
Institute control measures
Prevent similar occurrences in the future
Ultimate Concern of Epidemiology
Prevention of Diseases
Maintenance of Health
Public Health Importance of Epidemiology
It provides a framework for different approaches to control measures
Assessment of the Health Status of the Community (Community Diagnosis)
Types of Health Indicators
Health status indicators (morbidity/mortality)
Population indicators
Indicators for the provision of health care
Risk reduction indicators
Social and economic indicators
Environmental indicators
Disability indicators
Health policy indicators
Stages in the Natural History of Disease and the Levels of Prevention