Reporting Disease Occurence

Question 1

What 3 things make up the Epidemiologic Triangle?

Answer 1

• Host
• Environment
• Agent

Question 2

What does the Epidemiologic Triangle represent?

Answer 2

• Traditional model of causation for dz.
• whether or not a dz will occur in an individual

Question 3

What 3 things determine the level of DZ in a population?

Answer 3

• Individual factors
• Spatial factors
• Temporal factors

(who, when, where!)

Question 4

How may we report the occurence of a DZ & it’s frequency? (4)

Answer 4

• Onset in time
• By time series analysis
• Host related factors
• Geographical location
• Combo of above

Question 5

Temporal Dimensions of Dz focus on what?

Answer 5

Whether or not a DZ is endemic, sporadic, epidemic or pandemic

Question 6

How does an Endemic DZ occur?

(3)

Answer 6

• occurs at expected frequency
• present at all times
• usually low & predictable levels

Question 7

How does an Epidemic Dz occur?

(2)

Answer 7

• occurs at greater than expected frequency
• can be depicted graphically as epidemic curves

Question 8

When does a Sporadic DZ occur?

(3)

Answer 8

• single case or small cluster of cases
• infrequently
• irregular & unpredicatable

Question 9

List the 3 basic Epidemic Curves.

Answer 9

• Point Source Epidemic
• Continous, Common Source Epidemic
• Propagating Epidemic

Question 10

What type of Epidemic Curve is this?

Answer 10

Point Source

Question 11

List the characteristics of a

Point Source Epidemic Curve

Answer 11

• Population is subjected to the same BRIEF exposure over a defined period of time (usually 1 intubation period)
• Shape: rises rapidly, definite peak, followed by a decline
• No new cases occur once the point source is removed

Question 12

What type of Epidemic curve is this?

Answer 12

Continous, Common Source Epidemic

Question 13

List the characteristics of a

Continous, Common Source Epidemic.

Answer 13

• Prolonged exposure to the source over an extended period of time ( >1 intubation time)
• Sharp down slope= common source removed
• Gradual down slope= outbreak exhausts itself

Question 14

What type of Epidemic curve is this?

Answer 14

Propagating Epidemic

Question 15

______ epidemic occurs when a DZ is introduced through a single source and subsequently transmitted to others (2^O cases)

Answer 15

Propagating Epidemic

Question 16

What form of analysis uses information of patterns of DZ occurence obtained form temporal occurence?

Answer 16

Time Series Analysis

Question 17

Purpose of Time Series Anaylsis?

Answer 17

ID persons of high or low risk so causal assocations can be explored

Question 18

3 trends that influence patterns of DZ occurence?

Answer 18

• Short-term
• Cyclical (+ seasonal)
• Secular (long term)

Question 19

Trend Characteristics:

• Rise & fall of a DZ over > 1 yr.
• Regular, periodic fluctations in level of DZ occurence

Answer 19

Cyclical trends

Question 20

Trend Characteristics:

• Special case of cyclical trend
• periodic fluctuations in DZ incidence related to particular seasons

Answer 20

Seasonal Trends

Question 21

4 things that cause fluctuations in

Seasonal Trends?

Answer 21

• host density
• management practices
• vectors
• infectious agent survival

Question 22

Overall rise or decline in incidence occuring gradually over long periods of time

Answer 22

Secular Trend

Question 23

• Describes the proportion of a population, initially free of the DZ of interest, that develops the DZ over a given period of time.
• Refers to NEW cases of dz.

Answer 23

Incidence

Question 24

How do you calculate Incidence?

Answer 24

Per # of individuals

(unit of population expressed as whole #s & in smallest multiples of 10)

Question 25

* Proportion of the population at a given time that have the factor of interest. * Expressed either as a proportion btwn 0-1, as a %, or as a # per unit of population at risk

Answer 25

Prevalence

Question 26

How do you calculate **Prevalence**?

Answer 26

Question 27

Which measure takes into account the duration of disease?

Answer 27

Incidence

Question 28

An important measure of the burden of DZ in the population & is useful in developing health policies

Answer 28

Prevalence

Question 29

What is the relationship between Incidence & Prevalence?

Answer 29

**Prevalence** (P) **= Incidence** (I) **x Duration** of DZ (D) P = I x D

Question 30

What can cause a change in **Prevalence**? | (3)

Answer 30

_Changes in:_ * Incidence * Avg. Duration of DZ * Both Indicence & Duration of DZ

Question 31

Importance of Prevalence?

Answer 31

* Existing cases of DZ * Indentify major DZ problems * Identify/evaluate control strategies

Question 32

2 Reasons to use Incidence?

Answer 32

* predict population's health status * Assess the probablility that an animal w/in a population at risk may develop the DZ of interest

Question 33

Purpose of Data Visualization (mapping) & Data description?

Answer 33

Show the location of diseased animals w/in a defined geographical limit

Question 34

Purpose of Data modeling?

Answer 34

Test hypotheses & plan health policies

Question 35

Why is Cluster Analysis important?

Answer 35

* Classifies dz basedon time:location clustering to exipidite prevention/control * Determine whether or not the dz warrants concern (epidemic)

Question 36

Purpose of an Epidemic Curve?

Answer 36

main way to identify the source of a dz.

Question 37

Key characteristics of a Sporadic Dz?

Answer 37

* small # of cases * occurs rarely & w/o regularity * **no secondary cases**

Question 38

Incidence is usually expressed numerically in reference to what?

Answer 38

Population at risk

Question 39

How is prevalence expressed? | (3)

Answer 39

* proportion btwn 0 & 1 * a % * a unit of population at risk

Question 40

Prevalence does not take into account what?

Answer 40

Duration of the dz.