12.1-3

• What role do vector organisms play in the transmission of pathogens?

  They transmit pathogens from host to host.
• How do vectors contribute to the spread of disease?

  Vectors help spread disease over large geographical areas.
• What is the biggest current vector for disease transmission?

  Human trade and travel.
• What percentage of global deaths is caused by non-infectious diseases?

  70%
• What is epidemiology?


  Epidemiology is the scientific study and analysis of factors that determine and influence the frequency and distribution of disease in a defined population.
• What is the purpose of epidemiological studies?

  To develop programs used to prevent and control the development and spread of disease.
• What factors are included in epidemiological studies?

  • How common the disease is
  • Proportion of population affected
  • Number of deaths due to disease
  • Other factors affecting chances of survival
• Why must conclusions from studies regarding risk relate to all members of the population?

  To ensure that the findings are applicable to the entire population.
• What is a random sample?

  A random sample is one of many statistically possible samples where all have an equal chance of happening.
• What criteria must be satisfied to determine if key factors contribute to disease spread?

  1. Significant statistical correlation between proposed cause and disease

  2. Consistent cause-effect relationship across variables

  3. Temporal sequence or direct timeline

  4. Increased exposure correlates with increased risk

  5. Plausible relationship explaining clinical symptoms
• Why are viruses difficult to identify?

  Because they can't survive on their own and need host cells to grow.
• How are viruses identified when grown in host cells?

  Several strategies can be used depending on the purpose of identification.
• What is the cytopathic effect?

  Specific changes to host cells caused by viruses that can be seen under a microscope.
• What tests can be used to identify viruses?

  • DNA analysis
  • ELISA test
  • X-Ray diffraction
  • Electron microscope examinations
• How can bacteria and fungal pathogens be isolated from host cells?

  By centrifugation and filtering of samples.
• How are cells cultured for bacterial isolation?

  Cells are cultured on agar in Petri dishes.
• What distinct characteristics can be observed in bacterial colonies?

  • Colour
  • Shape
  • Elevation or surface of colony
  • Smoothness of colony edges
  • Odor
• What is the typical shape and color of most bacterial colonies?

  Most bacterial colonies have a circular shape and are either white, cream, or yellow in color.
• How do antibiotics help in identifying bacteria?

  Antibiotics inhibit the growth of bacteria, which can be used to identify how bacteria respond to them.
• What does Gram staining help determine about bacteria?

  It helps determine if bacteria are Gram-positive (pink) or Gram-negative (red).
• What is the purpose of monitoring disease in epidemiology?

  • To predict and minimize harm caused by outbreaks
  • To improve knowledge about factors contributing to outbreaks
• What is the mortality rate?

  The rate of death per population size, represented as a proportion (e.g., per 1,000,000 individuals per year).
• What is the case fatality ratio?

  The number of deaths among those who have contracted the disease, expressed as a percentage.
• What does R0 measure?

  R0 measures the number of people who become infected by a single person with the disease.
• What is herd immunity?

  Herd immunity occurs when a large part of a population (70-90%) develops immunity to a disease.
• How can herd immunity help in disease control?

  It can help slow or stop a disease's spread.
• What are some preventative measures against disease?

  • Personal hygiene
  • Avoid food contamination
  • Consume treated water
• What are the control measures for disease spread?

  • Contact tracing
  • Informs people who may have been infected
  • Identifies contacts to prevent reinfection
  • Identifies the source of infection
  • Protects the community from disease spread