epi

• Epidemiology


  The study of factors that determine the occurrence and distribution of disease in a population
• Epidemiologists


  Public health professionals who investigate patterns, causes of disease, and injury in humans
• Types of epidemiology

  • Classical epidemiology
  • Clinical epidemiology
  • Syndromic epidemiology
  • Infectious disease epidemiology
  • Chronic disease epidemiology
• Classical epidemiology


  • Population oriented
  • Studies the community origins of health problems
  • Interested in discovering risk factors
• Clinical epidemiology


  • Studies patients in health care settings
  • Improve prevention, early detection, diagnosis, treatment, prognosis, and care of illness in individuals
• Syndromic epidemiology


  • Looks for patterns of signs and symptoms that indicate an origin in bioterrorism
• Infectious disease epidemiology


  • Study of the complex relationships among hosts and infectious agents
• Chronic disease epidemiology


  • Addresses the etiology, prevention, distribution, natural history, and treatment outcomes of chronic health disorders
• Levels of scientific study of disease

  • Submolecular or molecular level
  • Tissue or organ level
  • Level of individual patients
  • Level of populations
• Stages of disease

  • Pre-disease
  • Latent disease
  • Symptomatic disease
• Primary prevention


  Health promotion and specific protection
• Secondary prevention


  Pre-symptomatic diagnosis and treatment
• Tertiary prevention


  Disability limitation for early symptomatic disease and rehabilitation for late symptomatic disease
• Mechanisms and causes of disease

  • Biological mechanisms
  • Social, behavioral, and environmental causes
• Host factors


  • Responsible for the degree to which the individual is able to adapt to the stressors produced by the agent
• Agents of disease or illness

  • Biologic agents
  • Chemical agents
  • Physical agents
  • Social and psychological stressors
• Environment


  Influences the probability and circumstances of contact between the host and the agent
• Vectors


  Effective transmitters of disease that have a specific relationship to the agent, the environment, and the host
• Types of vectors

  • Insects, arachnids, mammals
  • Human groups
  • Inanimate objects
  • Part of the environment
• Risk factors and preventable causes

  • Intrinsic factors
  • Extrinsic factors
• BEINGS model

  • Biologic and behavioral factors
  • Environmental factors
  • Immunologic factors
  • Nutritional factors
  • Genetic factors
  • Services, social factors, and spiritual factors
• Herd immunity


  When a vaccine diminishes an immunized person's ability to spread the disease, leading to reduced disease transmission
• Immunodeficiency


  Genetic abnormalities or infections, certain medications that impair the immune system
• Genetic epidemiology


  Addresses the distribution of normal and abnormal genes in a given population
• Heritability


  Contribution of genes relative to all determinants of disease
• Genetic screening


  Important in identifying problems in newborns and in determining susceptibility genes
• Iatrogenic disease


  Occurs when a disease is induced inadvertently by treatment or during a diagnostic procedure
• A change in one part of a system can lead to an inevitable change in other parts of the system
• Examples of solutions causing new problems

  • Vaccination and patterns of immunity
  • Effects of sanitation
  • Vector control and land use patterns
  • River dam construction and patterns of disease
• Synergism


  Interaction or combination of factors that produce a greater effect than the sum of their separate effects
• Antigenic shift


  A process by which 2 or more strains of a virus combine to form a new subtype of a virus
• Antigenic drift


  Accumulation of mutations within virus genes over time
• Global pandemic


  Widespread outbreak involving multiple continents
• Contributions of epidemiologists

  • Investigating epidemics and new diseases
  • Studying the biologic spectrum of disease
  • Surveillance of community health interventions
  • Setting disease control priorities
  • Improving diagnosis, treatment, and prognosis of clinical disease
  • Improving health services research
  • Providing expert testimony in courts of law
• Biologic spectrum of disease (Iceberg phenomenon)


  Variation in the severity of a disease process
• Field trials


  Randomized trials of preventive measures, important phase of evaluating a new vaccine
• Syndromic surveillance


  Epidemiologists contributing to national security
• Disease control priorities should be based not only on the currently existing size of the problem, but also on the potential of a disease to spread to others; its likelihood of causing death and disability; and its cost to individuals, families, and the community
• Diagnosis


  Process of identifying the nature and cause of a disease through evaluation of the clinical history, review of symptoms, examination or testing
• Prognosis


  Improved understanding through epidemiology, risk estimation