CPH

• John Snow: 'On the basis of available descriptive data, including the observations made by Farr, he postulated that cholera was transmitted by contaminated water through a then unknown mechanism'
• Chain of Infection

  Occurs when an agent is passed from one host to another and a suitable mode of spread allows an outbreak to develop. A chain of transmission must be present in order to cause an epidemic. Elements: Agent, Host, Environment
• Epidemiology


  • It began as the study of infectious diseases but has expanded to include the study of chronic diseases, health care organization, health care delivery, occupational and environmental health
• Hippocrates: 'The development of human disease is related to the external & personal environment of the individual. Environmental and behavioral issues associated with disease'
• Epidemiology


  The study of the frequency, distribution of diseases in human populations and the determinants of the observed distribution
• Between 1849 and 1854

  The Lambeth Company changed its water source to an area of the Thames free from the sewage of London, leading to a decline in cholera rates in those areas
• Agent

  • Any substance that can cause death, disease, or other biological malfunction in humans, animals, plants, or any other living organisms. 3 Types of Agents: Biological (bacteria, parasite, virus), Physical Force (earthquake, car crash, flood), Chemical Substances (gas, liquid, or solid which can be inhaled, ingested, absorbed, or injected)
• Reservoir (of an infectious agent)


  Any person, animal, arthropod, plant, soil, or substance in which an infectious agent normally lives and multiplies, on which the infectious agent depends primarily for survival, and where it reproduces itself in such a manner that it can be transmitted to a susceptible host
• John Graunt published The Nature and Political Observations Made Upon the Bills of Mortality


  1662
• Environment

  • Key Characteristics of Environment: Physical (Geology and Climate), Biologic (Insects that transmit the agent), Socio-economic (Crowding, sanitation, and the availability of health services)
• Components of Epidemiology

  Disease Frequency, Distribution of Disease, Determinants of Disease
• Modes of Transmission

  DIRECT TRANSMISSION: direct contact with soil, animals, or plants as well as contact between people. INDIRECT TRANSMISSION: no direct contact with the source. AIRBORNE, VECTOR-BORNE, VEHICLE-BORNE
• Health Promotion


  Process of enabling people to increase control over the determinants of health and thereby improve their health. Interventions: Health Education, Environment Modification, Behavioral Changes, Lifestyle Changes, Nutritional Intervention
• Secondary Prevention

  An action which halts the progress of disease and prevents complications. Interventions: Early Diagnosis and Treatment, Referral
• Specific Protection

  Efforts directed towards protection against specific diseases. Interventions: Immunization, Use of Specific Nutrients, Chemoprophylaxis, Protection Against Occupational Hazards, Protection Against Accidents, Control of General Environment, Avoidance of Allergens
• Scope of Epidemiology

  Causation of the disease, Natural history of the disease, Health status of the population, Evaluation of interventions
• Host

  • The person or organism that is susceptible to the effect of an agent. Key Characteristics of a Host: The status of the host is generally classified as susceptible, immune, or infected. The host’s response to exposure varied widely from showing no effect to manifesting sub-clinical disease, atypical symptoms, or severe illness
• Types of Rehabilitation

  • Medical Rehabilitation, Vocational Rehabilitation, Social Rehabilitation, Psychological Rehabilitation
• Applications of Epidemiology in Public Health

  Preventing disease and promoting health, Community health assessment (community diagnosis) and priority setting, Improving diagnosis, treatment, and prognosis of clinical diseases, Evaluating health interventions
• Examples of Rehabilitation


  • Exercises in Neurological Disorders, Prosthetic Restoration of Lost Tooth, Reconstructive Surgery in Leprosy
• Aims and Objectives of Epidemiology

  To eliminate or reduce the health problems of the community, To promote the health and well-being of society as a whole, To describe the distribution and magnitude of health and disease problems in human populations, To identify etiological factors (risk factors) in the pathogenesis of disease, To provide data essential to the planning, implementation, and evaluation of services for the prevention, control, and treatment of disease and setting priorities among those services
• Epidemiology and Clinical Medicine


  In Clinical Medicine, the unit of study is a “case” but in epidemiology, the unit of study is “defined population” or “population at risk”. Physicians are concerned with the disease
• Epidemiology

  1. INCUBATION PERIOD

  2. PRODROMAL PERIOD

  3. LATENT PERIOD
• Levels of Prevention


  PRIMARY PREVENTION, SECONDARY PREVENTION, TERTIARY PREVENTION
• William Farr was responsible for medical statistics in the Office of the Registrar General for England and Wales


  1839
• Tertiary Prevention


  Used when the disease process has advanced beyond its early stages. Interventions: Disability Limitation, Rehabilitation
• Key Characteristics of Agents

  • Infectivity, Pathogenicity, Virulence, Transmissibility
• Epidemiology and Public Health


  Public health refers to collective actions to improve population health. Epidemiology is one of the tools for improving public health
• Broad Categories of Design Strategies in Epidemiologic Research

  Descriptive Epidemiology, Analytic Epidemiology
• Epidemiology

  Epidemiologist seeks to identify the source of infection, mode of transmission, and etiological factors to determine future trends, prevention, and control measures
• Physician


  Concerned with the disease in the individual patient
• Tools of Measurements in Epidemiology

  • Rate
  • Ratio
  • Proportion
• Prevalence is the total number of existing cases (old + new) in a defined population at a particular point in time or specific period of time
• Infant Mortality Rate measures the risk of dying during the 1st year of life
• Health Indicators

  • Population
  • Livebirths
  • Leading Causes of Morbidity
  • Total Deaths
  • Fetal Deaths
  • Maternal Deaths
  • Infant Mortality
  • Leading Causes of Mortality
  • Immunizable Diseases
  • Selected Causes of Death
  • Child Mortality
• Epidemiology


  • One of the tools for improving public health
• Epidemiology is concerned with both the sick and the healthy
• Rate measures the occurrence of a specific event in a population during a given time period
• Incidence is the number of new cases occurring in a defined population during a specified period of time
• Collective actions are taken to improve population health