week 5 lecture 2: epidemiology 2

• what are the 3 essential characteristics of disease in descriptive epidemiology?

  1. time
  2. place
  3. person
• what are 3 things to consider with time, in the context of descriptive epidemiology?

  1. stability
  2. seasonal variability
  3. clustered (epidemic) or evenly distributed
• what 3 things must be done when undertaking an analytical epidemiological study?

  1. know where to look
  2. know what to control
  3. formulate a hypothesis compatible with laboratory evidence
• what is the 'triad' of factor that must be considered in analytical epidemiology?

  1. host
  2. agent
  3. environment
• what organism is normally being referred to when the term 'host' is used?

  humans
• give 3 factors that must be considered about the host, when studying analytic epidemiology

  1. environment
  2. immunological state
  3. age
• give 3 factors that must be considered about an agent, when studying analytic epidemiology

  1. nutrients
  2. poisons
  3. radiation
• give 3 factors that must be considered about the environment when studying analytic epidemiology

  1. crowding
  2. atmosphere
  3. vectors
• what is the difference between descriptive and analytic epidemiology?

  Descriptive: summarises known data on disease occurrence Analytic: investigates causes and associations of disease
• what does determination of information about the host, agent, and environment require?

  field-based work, not laboratory
• what is mortality rate?

  a measure of the number of deaths in a particular population, per unit of time
• mortality rate is the main source of frequency of disease (i.e., death certificates)
• what is a consequence of diseases not leading to mortality (i.e., dermatitis)?

  it is often under-estimated in populations
• what kind of (mortality data) analysis is required in poor countries?

  prospective (expected) rather than retrospective
• what are the 5 steps of epidemiology?

  1. verify the outbreak
  2. plot an epidemic curve
  3. calculate attack rates
  4. determine the source of the epidemic
  5. recommend control measures
• what is an attack rate?

  the proportion of people who become ill/die of a disease in a population initially free of the disease
• the vast majority of outbreaks are food-borne
• what are the 3 types of food contamination?

  1. physical
  2. chemical
  3. biological
• name 3 physical types of food contamination

  1. glass
  2. metal fragments
  3. bone
• name 3 chemical types of food contamination

  1. pesticides
  2. poisonous metals
  3. additives and preservatives
• name 6 biological types of food contamination

  1. bacteria
  2. viruses
  3. fungi
  4. yeast
  5. parasites
  6. insects
• what are the 4 main requirements needed for a bacteria to survive?

  1. food
  2. water
  3. pH
  4. temperature
• what kind of food does bacteria require?

  'potentially hazardous'
• give 3 examples of food that bacteria thrive in

  1. milk
  2. egg
  3. meat
• what general kinds of food does bacteria thrive in?

  high-protein and moist
• bacteria requires moisture to thrive
• what symbol is used to denote water activity?

  Aw
• what is water activity?

  the amount of water available in food
• what is the lowest water availability at which bacteria will grow?

  0.85
• what water activity value do most potentially hazardous foods have?

  0.97-0.99
• at what type of pH do most bacteria grow best at?

  neutral/slightly acidic
• why does bacteria require water?

  to transport nutrients into the cell and take away waste products (aids metabolism)
• what pH value range do potentially hazardous foods have?

  4.6-7.0
• what is the danger zone?

  the temperature where most bacterial growth occurs
• what is the danger zone for potentially hazardous foods?

  45-140 F
• give 4 major causes of foodborne diseases?

  1. improper cooking of foods
  2. improper cooling of foods
  3. improper reheating of foods
  4. cross-contamination
• how does ecological epidemiology usually treat host (human) populations, and what does it primarily focus on?

  it treats host populations as fixed in size. and focuses on the dynamics of disease within this population
• what distinguishes ecological epidemiology?

  acknowledgement of the fact that the dynamics of the parasite and host populations may interact
• what 'level' does Filoviridae?

  'family' of viruses
• what order does Filoviridae belong to?

  Mononegavirales