Investigating of Outbreaks

Question 1

Definition fo Outbreak

Answer 1

Outbreak = Epidemic
an excess of cases in geographic region

occurs in groups
it is a change in the amount of a disease

Question 2

What causes an outbreak?

Answer 2

Changes in

environment, host, agent

Question 3

Individuals in outbreaks share what characteristics?

Answer 3

Outcome:
common disease that occur close in time (cluster in time) and in similar geographic location (cluster in space)

Exposures
common risk factors/ determinants

Question 4

T / F : Case control studies are most common in outbreaks and food borne illness outbreaks?

Answer 4

TRUE

Question 5

Outbreak investigation goals?

Answer 5

characterize outbreak (descriptive Epi)
         who, place, time, pattern

ID casual factors (analytical Epi)
pathogen, risks/determinant, exposures
cause or assoc. of outbreak

Implement cost effective control/ prevention interventions

Evaluate interventions (analytical Epi)

Question 6

ID an outbreak at what levels?

Answer 6

State/ regional level (surveillance & reportage dz programs)

Farm level

Question 7

Outbreak Investigation Steps?

Answer 7

establish

 1. an outbreak
 2. Diagnosis
 3. case definition
 4. magnitude
 5. Describe outbreak (who, place, time)
 6. Develop hypothesis
 7. test hypothesis
 8. design intervention
 9. evaluate intervention

Question 8

1. Establish it is an outbreak

Answer 8

is there truly excess cases in region?
easy for non-endemic (foreign/ tranboundary) diseases

difficult for endemic or production problems
require Hx

Question 9

3. Establish a case definition

Answer 9

2 parts important

1. Species characteristics shared with dz
2. species characteristics that distinguish dz from non-dz 

Must be precise as possible
failure of precision will cause investigation to be bias

Question 10

T/ F Non- cases may have the exposure?

Answer 10

True
IP vary among diseases
not all animals get sick

Question 11

4. Establish he magnitude

Answer 11

Enhance surveillance

   - heighten awareness
   - Targeted surveillance

Question 12

5. Describe Outbreak (who, place, time) ?

Answer 12

Be very observant
Collect historical, clinical, and productive data on cases and non-cases.

who:
age, sex, breed, production type/ stage, repro stage

place:
describe characteristics of cases and non-cases
DRAW A MAP

time: (be objective)
temporal pattern , date, check records,
epidemic curve
estimate attack rate

Question 13

6. Develop hypothesis

Answer 13

compare potential exposures and risks between cases and non-cases

dont limit to 1 hypothesis

Question 14

7. Test hypothesis

Answer 14

Analyze data
calculate exposure measurement
ID factors
biological relevance, stat signifigance, assoc. strength

Question 15

8. Design interventions

Answer 15

-ID most important risks
Dont always require exact etiology

-consider
facilities, management, cost budget, client resources

Question 16

9. Evaluate intervention

Answer 16

at farm level
monitor interventions over time
want to ensure economic benefit

state level
implement surveillance to test values of intervention