ORAL QUESTIONS & ANSWERS IN EPIDEMIOLOGY.
1. Define the terms-Sampling, sampling unit, sampling frame,& sampling scheme
ANS;
Ø Sampling: The process of selecting any portion of a population as representative of that population.
Ø Sampling Unit: An element or set of elements considered for selection in some stage of sampling
Ø Sampling Frame: A list of all the sampling units in the population
Ø Sampling Scheme: A method of selecting sampling units from a sampling frame.
2.Define Convenience sampling.
Ø Convenience Sampling: The sample is obtained on convenience basis. Investigators select the study units that happen to be available at the time of data collection. (Many hospital-based studies use convenience samples). A major limitation of this approach is that the sample drawn may be quite unrepresentative of the study population
3.Mention types of probability sampling
ANS;-
· Simple random sampling
· Systematic Sampling
· Stratified Sampling
· Cluster Sampling
· Multistage Sampling
4.Explain how to get a sample in systemic sampling.
ANS;
• In systematic sampling, elements in the sample are obtained in a systematic way.
5.Define Epidemiology.
ANS;
Epidemiology: The study of the distribution and determinants of health-related states or events in specified populations, and the application of this study to the control of health problems.
6.Definition of HEALTH.
ANS;
Health: A state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity. (World Health Organization)
7. What is a meaning of a disease Determinant.
ANS;
Disease determinant: A factor which determines the nature or outcome of a disease.
8. Provide an examples of determinant s/factors influencing disease.
ANS;
· Age
· Sex
· Genetic
· Ethnicity
· Iron and folic acid
· Cholesterol
· Protozoa ( e.t.c)
9. Mention four types of factors that play part in causation of a disease
ANS;
· Predisposing Factors
· Enabling Factors
· Precipitating Factors
· Reinforcing Factors
10. Four levels of disease prevention in Epidemiology;
ANS;
· Primordial Prevention
· Primary Prevention
· Secondary Prevention
· Tertiary Prevention
11. Define-Mean,mode,& median.
ANS;
v The mean; is simply the arithmetic average of the data and is calculated by taking the sum of all values in the number set and dividing that total by the number of values in the dataset.
v The median; is the 50th percentile of the values in a dataset and represents the literal middle of the dataset.
v The Mode; represents the value that is found most frequently in a set of numbers, though it is not often used.
12. Define a variable
ANS;
Variable: A term for a characteristic that is different in different members of a population or sample, such as height.
13.Mention types of variables.
ANS;
v Qualitative (categorical) variables
v Quantitative (numerical) variables
14. Explain the difference between discrete and continuous variables
ANS;
Discrete variables take only fixed values, in most cases whole numbers, for example:
· Parity: 0, 1, 2, 3, 4, 5, 6, 10
· Age last birth day: 5, 19, 45, 90
· Counts: 1, 2, 3, 4, 5, 9
· Number of AIDS cases: 100, 10000, 34278.
Continuous variablestake any value within meaningful extremes, for example:
· Height (cm): 159, 25, 160.35
· Weight (kg): 71.12, 80.56
· Exact age like 21 yrs 6 months and 4 days
15. Mention ways you can use to present data
ANS;
· Table,
· Histograms,
· line diagrams,
· frequency polygons, and
· cumulative frequency curves
16.Mention the advantages of a cluster sampling
ANS;
· Simple, as no list of units required
· Less resources required
17.Define Ecology
ANS;
Ecology: The study of the relationship between organisms and their environments.
18.Define CLIMAX STATE in relation with Ecology.
ANS;
Climax State - This is the final constant condition of flora and fauna in a specified geographic area
19.What is population density
ANS; Population means all the inhabitants of a particular place, and density refers to the quantity of people or things in a given area or space
20.What is Herd Immunity?
2O.What is Herd Immunity?
ANS;
Herd immunity is the ability of a community to resist disease. It can occur naturally by exposure to infection or artificially by vaccination.
21.Explain the epidemiological models of disease causation.
ANS;
Disease does not occur due to a single factor, but due to a number of interrelated factors.
• These factors can be divided into two categories:
- Essential/Necessary Factors
-Contributory Factors
• Essential/necessary factors are ‘required ingredients’ for disease to occur.
Ø These are agents of disease such as bacteria and viruses in infectious diseases, and fire, nutrition, radiation or various poisons in non-infectious diseases.
• Contributory factors are host environment factors that are associated with increased likelihood of disease occurrence.
· For example: ƒ Host Factors: immunity, sex, age, etc. ƒ Socio-economic factors: poverty, development, etc. ƒ Physical/Environmental Factors: rainfall, temperature, etc. ƒ Biological Factors: presence of vectors, animal reservoirs, etc
22. Explain Natural History of a disease.
ANS;
Natural History of Disease: Refers to the course of a disease over time, when unaffected by any human intervention like prevention, treatment or rehabilitation
23.Define Pathogenesis
ANS;
Pathogenesis: The step-by-step origination and development of a disease
24. Mention Host factors Responsible for Pre-pathogenesis.
ANS;
Host factors include:
· Age ƒ
· Sex ƒ
· Social class ƒ
· Personality ƒ
· Genetic factors ƒ
· Education ƒ
· Marital status
v Note: a hostis an organism capable of being infected by an agent.
25.Mention Agent factors related to the survival the Micro-organism in external environment.
ANS;
These include:
· Infectivity ƒ
· Pathogenicity ƒ
· Virulence ƒ
· Antigenicity
26.Define Primordial Prevention
ANS;
Primordial prevention: Preventing agents or risk factors; preventing the interaction between host, agent and environmental factors, so that disease may not occur
27. Define Disease Prevention
ANS;
Disease Prevention: Inhibiting the development of a disease before it occurs.
28. Define Primary Prevention
ANS;
Primary prevention: preventing healthy people from becoming ill.
29. Give FOUR examples of Primary prevention
ANS;
Examples of primary prevention include:
§ Immunization
§ Wearing shoes to prevent hookworm
§ Adequate intake of proteins and vitamins to prevent malnutrition
§ Use of mosquito nets to prevent malaria
§ Health education and promotion initiatives aimed at fostering positive health behaviors
v ƒ For example, promoting the use of latrines, promoting condom use, etc
30.Mention 5 Components necessary for disease transmission in Humans
ANS;
Transmission of diseases in humans requires the following components:
· An agent, capable of infecting a human
· A source (an infected host or reservoir of infection)
· A portal of exit from the source
· A suitable means of transmission
· A portal of entry into a new, susceptible host.
31. Define Agent of a disease.
ANS;
Agent: the etiological factor which must be present for the disease, disability or pathological state to occur in a susceptible host.
32. Define Infectivity.
ANS;
Infectivity: The capacity of a micro-organism to enter a susceptible host.
33. Define Pathogenicity.
ANS;
Pathogenicity: Refers to the capacity of a micro-organism to cause overt disease in the infected host
34. Mention 4 Portals of Exit in the Human Host
ANS;
Portals of exit in humans:
· Respiratory passages
· Alimentary canal
· Openings in the genitor-urinary system
· Skin lesions
35. Give Examples of Horizontal transmission of adiseases
ANS;
Examples of horizontal transmission of diseases include:
· Droplet infection ƒ
· Faeco-oral route ƒ
· Genital ƒ
· Direct skin contact
36. Mention types of vectors
ANS;
· Mechanical vectors
· Biological vectors
37.Mention two broad categories of epidemiological studies
ANS;
· Observational Studies
· Experimental Studies
38. Mention two types of observational study
ANS;
There are two types of observational studies:
§ Descriptive Studies
§ Analytical Studies
39.Mention studies included a Analytical studies
ANS;
Examples of analytical studies include:
§ Ecological Studies
§ Cross-sectional Studies
§ Cohort Studies
§ Case-Control Studies
40. Mention three methods of hypothesis formulation
ANS; There are three methods of hypothesis formulation
§ Method of Difference
§ Method of Agreement
§ Method of Concomitant Variation
41. Define disease surveillance
ANS;
Disease surveillance –Is a systematic collection, analysis, and use of information for the control of a specific disease
42. Mention 2 types of Case-control study designs
ANS;
Types of Case-Control Study Designs
• Retrospective Case-Control Design
• Prospective Case-Control Design
43. Mention 4 major steps in Case-control study
ANS;
Major Steps in Case-Control Study
• Define and select cases
• Select controls
• Ascertain exposures
• Compare exposure in cases and controls by obtaining proportions or odds ratios.
• Test any differences for statistical significance.
44. Define Screening in epidemiology
ANS;
Screening: The examination of asymptomatic people in order to classify them as likely or unlikely to have the disease of interest.
45. Mention 3 Examples of screening test.
ANS;
Examples of Screening Tests;
· Pap smear
• Mammogram
• Clinical breast exam
• Blood pressure determination
• Cholesterol level
• Eye examination/vision test
• Urinalysis
46. What do you understand by Mass screening?
ANS;
Mass screening: Is a screening of a whole population.
47. What level of prevention is mass screening?
ANS;
MASS SCREENING is a secondary level of prevention.
48. What do you understand by Targeted screening?
ANS;
Targeted screening: Is a screening of groups with specific exposures.
49. Define sensitivity and specificity of a test.
Ø
Ø Specificity: The ability of a test to give a negative finding when the tested person is truly free of the disease under study.
50. What is a sensitivity of a screening test
ANS;
Sensitivity: The ability of a test to give a positive finding when the tested person truly has the disease under study
51. Define Endemic Disease
ANS;
Endemic Disease is a diseases which are continuous and/or habitually transmitted in populations throughout the year (such as malaria)
52. Define Epidemic
ANS;
Epidemic: The occurrence of more cases of a specific disease in a population that is clearly in excess of the expected incidence in a specified period of time.
53. Define Pandemic disease
ANS;
Pandemic Disease this is expressed when an epidemic spreads to affect many countries globally
54. Mention 3 types of epidemics
ANS;
Ø Common Source epidemic
Ø Propagated (Progressive) Epidemic
Ø Mixed epidemic
55. Define propagated (progressive) Epidemic
ANS;
Propagated epidemics result from transmission of an infectious agent from an infected host to a susceptible one.
56. Mention things that should be done in preparation for Field Work
ANS;
• Assemble a team (rapid response team).
• Assemble relevant supplies and equipment (transport media, specimen bottles, information/education/communication (IEC) materials, treatment guidelines & medical supplies, transport, communication means, investigation and surveillance forms, funds, fuel, etc).
• Alert district authorities
57. Explain how do you Establish Existence of an epidemic
ANS;
• Compare observed incidence with expected:
- No seasonality: compare with incidence from previous weeks/ months,
- Seasonality: compare incidence from similar periods of earlier years.
• Use action threshold.
58. Integrated diseases surveillance and Response.
ANS;
Ø Integrated Diseases Surveillance and Response: A strategy proposed and adopted by the World Health Organization/AFRO Regional Assembly in 1998 to strengthen disease surveillance in member countries using an integrated approach.
59. Define standard case definition
ANS;
Standard Case Definition Is a set of standard criteria for deciding whether a person has a particular disease or other health condition by specifying clinical criteria and limitations on time, place and person.
6o.Define disease control, prevention and eradication
ANS;
Control of Disease: Reduction of disease prevalence to a level where it is no longer a public health problem.
Prevention of Disease: Any activity which reduces the possibility of occurrence, or the burden of morbidity, disability or mortality of a disease
Eradication of a disease is a process of removing completely disease from occurring in environment.
1. What differentiates a clinician from an epidemiologist?
2. There is an outbreak in Mwendakulima, what epidemiological method of study suits the case and gives reasons?
3. Define Screening/testing of the disease.
4. Cohort study design.
5. Case-control study design.
6. Define the word sampl
7. Differentiate Statistic and parameter.
8. What is natural history of the disease?
9. Explain to the layman so that he can capture the meaning of Epidemiology.
10. Mention three importance of biostatistics.
11. Define what is qualitative data?
12. Define Primary Data.
13. Define Secondary Data.
14. Define Quantitative Data.
15. Mention three epidemiological disease causation models.
16. Differentiate Data and information.
17. What is Biostatistics?
18. What is Data?
19. Mention four levels of disease prevention in epidemiology.
20. Mention two epidemiological disease causation theories.
21. Define HEALTH according to World Health Organization( WHO 1948).
22. Determinants of Health and Diseases can be grouped into four groups , name them.
23. Mention four Types of screening methods
24. Define Climax state.
25. What is Food Chain?
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