CHAPTER 13

• What does the term epidemiology mean?

  Study of health and disease in populations
• What are the components of the word epidemiology?

  Epi (upon), demos (population), logos (study)
• What is a case in epidemiology?

  A disease individual or group
• What is an index case?

  The first diagnosed case in an outbreak
• How is the index case related to Patient Zero?

  They are equivalent terms in epidemiology
• What does veterinary epidemiology focus on?

  Diseases in animal populations
• What factors affect disease occurrence in veterinary epidemiology?

  Welfare, health, and management factors
• What are determinants of disease?

  Factors affecting disease frequency
• How are determinants of disease categorized?

  Primary, secondary, intrinsic, extrinsic
• What is herd immunity?

  Proportion of immune individuals in a population
• What is quarantine in epidemiology?

  Separation of exposed carriers from others
• What are primary determinants of disease?

  Necessary causes of disease
• What are secondary determinants?

  Predisposing or enabling risk factors
• What are intrinsic determinants?

  Factors internal to the host
• Give an example of intrinsic determinants.

  Age, sex, behavior, immunity
• What are extrinsic determinants?

  Factors external to the host
• Give an example of extrinsic determinants.


  Trauma, location, husbandry
• What is absolute frequency?

  Raw number of times an event occurs
• What is relative frequency?

  Ratio of event occurrence to total occasions
• How is relative frequency expressed?

  As a proportion or percentage
• What is a count in epidemiology?

  The absolute number of cases
• What is a ratio?

  Relative magnitudes of two quantities
• What are the three important pieces of information in a data statement?

  Number, place, time
• What is a proportion?

  Magnitude of a part divided by the whole
• What is incidence?

  Number of new cases in a population
• What formula is used for cumulative incidence?

  New cases divided by healthy individuals
• What is incidence rate?

  Measures rapidity of new disease cases
• What formula is used for incidence rate?

  New cases divided by time at risk
• What is cumulative incidence rate?

  Proportion of non-diseased that become diseased
• When is cumulative incidence rate used?

  When population is stable and risk period is short
• What does "withdrawn" mean in epidemiology?

  Not included in population for reasons other than disease
• What is point prevalence?

  Proportion of population with disease at a time
• What does point prevalence describe?

  Current disease state in a population
• What does attack rate refer to?

  Incidence during an outbreak in a defined population
• What formula is used for attack rate?

  New cases divided by time at risk
• What is secondary attack rate?

  Proportion of cases from contact with primary case
• What is prevalence?

  Proportion of population in disease state at a time
• What does point prevalence measure?

  Probability of disease at a specific moment
• What formula is used for point prevalence?

  Individuals with disease divided by population at risk
• What is period prevalence?

  Proportion of population that had disease over time