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• Epidemiology


  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

  • Stage of Susceptibility (Pre-pathogenesis Stage)
  • Stage of Subclinical Disease
  • Stage of Clinical Disease
  • Stage of Recovery, Disability, or Death