Outbreak Investigations

Question 1

primary purpose of outbreak investigations

Answer 1

to control the spread of disease

Question 2

circumstances that can make outbreak investigations unique

Answer 2

1. limited cases: limited stat power
2. the public view might cause additional responses (hypochondriacs)
3. data collection may not be consistent
4. outside pressures to conclude the investigation

Question 3

flow of information/data in outbreak invesitgations

Answer 3

lab, hospital, individual > county health dept > state health dept > federal (CDC) > international (WHO)

Question 4

the state reporting system

Answer 4

drs, labs, hospitals, nursing homes, daycares, are required by law to report to the county health department

Question 5

what to do when you recieve a report

Answer 5

investigate every report if possible: risk factors, identify other cases, prevention/treatment, education

Question 6

how to know if you should begin an investigation

Answer 6

know the baseline rate! determine if there is concern based on the expected number of cases

Question 7

steps in an outbreak investigation:

Answer 7

1. prepare for field work
2. confirm diagnosis and confirm outbreak
3. identify cases and exposed
   2a. case definition
4. choose a study design
5. collect risk info
6. analyze info: time, place, person
7. collect lab specimen
8. environmental investigation
9. implement control measures
10. formulate and test hypotheses
11. conduce additional systematic studies
12. communicate findings

Question 8

1. prepare for field work

Answer 8

have the tools needed: equipment, staff, ppe, vaccination, contact list

Question 9

2. confirm diagnosis and confirm outbreak

Answer 9

is it a lab confirmed case? over the baseline rate? what population or time of year?

Question 10

3. identify cases and exposed persons

Answer 10

make a case definition and identify cases.
review lab data, survey professionals, interview known cases

Question 11

confirmed case definitions:

Answer 11

confirmed lab, time, place, and/or symptoms

Question 12

probable case definitions

Answer 12

usually includes time, place, and symptoms, but usually no confirmed lab

Question 13

choose your study design

Answer 13

based on the size and availability of the exposed population: can you identify all of the potential exposed invidual:
cohort study or case control study

Question 14

5. collect risk information

Answer 14

use surveys asking questions that will answer person, place, and time

Question 15

6. Tabulate data

Answer 15

make line listings, maps, and epi curve

Question 16

what are some things that are included in a line listing

Answer 16

case number, date of report, date of onset, diagnosis, age, sex, exposure, lab tests, symptoms, etc.

Question 17

epi curve for point souce

Answer 17

one point, and then a cluster of cases

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Question 18

epi curve for a common source outbreak

Answer 18

longer range of time with observed cases

Question 19

propogated outbreak epi curve

Answer 19

multiple peaks shown, with increasing peaks as time goes on

Question 20

how to find exposure on an epi curve from a point source outbreak

Answer 20

take peak out outbreak, count back from the average incubation period, and then take the earliest case, and count back from the minimum outbreak period

Question 21

7. collect specimens for lab analysis

Answer 21

Identify the etiological agent:
Food, water, oil, air, blood, sputum, stool

Question 22

8. environmental investigation

Answer 22

see the conditions and the role they play within the population, e.g. are people washing their hands, how are they preparign the food

Question 23

9. control measures

Answer 23

quarantining, test contacts, prophykaxis, close facilities

Question 24

10. test and formulate hypotheses

Answer 24

formulate your hypotheses based on time, place, person, agent, transmission
you want to see if there is an association between E and O, how strong the association is, is there increased risk with exposure, and how many cases are attributed to the exposure

Question 25

cohort study

Answer 25

you need to be able to identify every person in the cohort so choose wisely (sport team, wedding, coworkers) use RISK RATIO RR>3 is rule of thumb

Question 26

case control study

Answer 26

identify cases and controls and then ask about exposures USE ODDS RATIO OR>4 is rule of thumb

Question 27

Confidence interval

Answer 27

for measures of association, you do not want it to include 1

Question 28

p value

Answer 28

helps you determine the significance of your results

Question 29

11. additional studies

Answer 29

epi research, lab investigations, clinical presentations, modes of transmission

Question 30

12. communicate findings

Answer 30

final report includes a summary of findings outcomes, and recs, and is submitted to the dept of health.