Epidemiology

Question 0

Outline Kocks postulates.

Answer 0

To cause disease pathogens must:
Found in all cases of disease
Prepared and maintained in pure culture
Capable of producing the original infection after several generations of culture
Retrievable from an infected animal and able to be cultured again

Question 1

Who first suggested that some diseases were caused by microorganisms?

Answer 1

Louis Pasteur

Question 2

What was Rudolph Virchows famous quote about One Health?

Answer 2

Between animal and human medicine there is no dividing line… And nor should there be.

Question 3

Describe the Anti-Germ theory.

Answer 3

Epidemics are of social origin - use politics to combat
Disease agents used bodies as habitats (didn’t cause disease)
Social change could be used to combat disease

Question 4

Why is Roisin great?

Answer 4

Because she’s lovely, kind, pretty, smiley, funny and I (Nicole) am very lucky to have such an ace friend!

Question 5

Association

Answer 5

Reverse causation

Question 6

Eradication of Rinderpest.

Answer 6

2011

Question 7

What problems are there with “cause = infectious agent” ?

Answer 7

Multi causal disease:
Infectious agent
Environmental factors - husbandry, stress
Immunological factors

It is important to control the infectious agent and the other factors which are affecting welfare

Question 8

Outline Hill-Evans postulates.

Answer 8

Vague points, not all need to be fulfilled ***add

Question 9

Confounder

Answer 9

A third variable which affects both cause and outcome and therefore can distort results.

Question 10

Structural violence

Answer 10

Exerted by society

Question 11

What effect does increased sample size have on random error and selection bias?

Answer 11

Random error decreases

Selection bias does not change

Question 12

Risk

Answer 12

The chance of encountering some form of harm, loss or damage.
Remember, chance = probability, harm, loss or damage = consequence

Question 13

Outline the basic framework for reducing risk.

Answer 13

Risk analysis - risk management - risk communication

Question 14

Why should we use risk assessment?

Answer 14

Structures decision making - evidence based, allows us to identify gaps in data.
Useful in context with HACCP - identify hazards
International trade - common understanding of food safety

Question 15

How does the OIE framework for risk assessment work? (x4 and brief description)

Answer 15

Hazard identification - identify pathogens potentially present in animals.
Release assessment - what is the prob that the agent will be introduced to the given environment?
Exposure assessment - probability that native animals are exposed to agent.
Consequence assessment - consequences if exposure, probability of occurrence

Question 16

How does the CODEX framework for risk assessment work?

Answer 16

Hazard identification - hazard characterization - exposure assessment - risk characterization
Focus specifically on food-borne risks from microbial hazards

Question 17

CODEX model

Answer 17

Assessing necessity of regulatory controls and their associated impact

Question 18

OIE

Answer 18

Emphasis on assessing risks actually present in a given situation

Question 19

Hazard

Answer 19

The identification of biological, chemical and physical agents capable of causing adverse health effects and which may be present in particular food groups (CODEX)

Question 20

Exposure assessment

Answer 20

Models used to assess the likelihood of exposure of the population to the agent. Flow charts are useful.
Can be characterised qualitative (red, orange, green) or quantitatively spending on data available or need.

Question 21

Quantitative risk assessment

Answer 21

Numerical probabilities are given for each stage of a risk assessment model

Question 22

Risk characterization

Answer 22

Integration of hazard identification, characterization and exposure to obtain a risk estimate

Question 23

Compare uncertainty and variability.

Answer 23

Uncertainty can be reduced by collecting more data whereas variability requires us to estimate more precisely

Question 24

Prevalence

Answer 24

Diseased/ population at one time

The rate of a condition

Question 25

Differentiate between incidence rate and risk.

Answer 25

Rate - new cases/ total at risk (in a particular time period)
Risk - probability of and event occurring in an individual in a certain period

Question 26

With low incidence how do prevalence and incidence relate to one another?

Answer 26

Prevalence = incidence x duration

Question 27

Relative risk

Answer 27

The risk ratio (risk = cases/ population @ risk)

Risk ratio = risk a/ risk b

Question 28

Odds ratio

Answer 28

Exposed cases / exposed controls divided by non-exposed cases/ non-exposed controls

Question 29

Differentiate between attributable risk and rate.

Answer 29

Risk = risk of a disease attributed to the risk factor
Rate = rate in exposed attributed to the risk factor

Question 30

A decrease in p value for a particular statistic means what?

Answer 30

Increased significance of the particular risk factor (you are more sure that it caused x)

Question 31

Predictive values

Answer 31

Positive - probability of being diseased if the test diagnoses you as so.
Negative - probability of being disease free if the test diagnoses you as so.

Question 32

Sensitivity

Answer 32

True positives diagnosed as such

Question 33

Specificity

Answer 33

True negatives diagnosed as such by the test

Question 34

Differentiate between apparent and true prevalence.

Answer 34

Apparent uses test positives rather than truely diseased animals