Epi Chapter 10

Front 1

What is field epidemiology?*

Back 1

The application of epidemiology under a set of general conditions:
-The problems is unexpected
-A timely response may be demanded
-Travel to and work in the field is required by epidemiologists to solve the problem
-The investigation time is likely to be limited because of the need for a timely intervention

Front 2

What are the three important ways that field investigations involving acute problems may differ from conventional epidemiologic studies?

Back 2

1. Field investigations often do not start with a clear hypothesis
2. Acute problems involve an immediate need to protect the public and resolve the concern
3. Field epidemiologists must decide when the available information is sufficient to take appropriate action

Front 3

How many steps are there in field investigation?

Back 3

14

Front 4

1. Establish the existence of an epidemic (or outbreak)*

Why are attack rates an appropriate statistics for investigating disease outbreaks?

Back 4

Because they describe rapidly occuring new cases of disease in a well-defined population over a limited time period

Front 5

1. Establish the existence of an epidemic (or outbreak)*

What are attack rates usually calculated by?

Back 5

By person characteristics (Ex. age, sex, race, ethnicity, and occupation) in order to identify high-risk groups

Front 6

2. Confirm the diagonosis*

Back 6

-Assessment of the cinical findings should be done to assure correctness and reliablity of the findings
-Clinical diagnosis by appropriately trained individuals
-Laboratory diagnosis

Front 7

3. Establish criteria for case identification*

Back 7

-Standard clinical criteria (what)
-Loose case definition vs. sstrict case definition
-A case may be further characterized by: who, when, where

Front 8

What is the deciding factor for loose case definition vs. strict case definition*

Back 8

Time

-loose case: spreading at a fast rate
-strict case: spreading at a slower rate, not impacting population as much

Front 9

4. Search for missing cases*

Back 9

Investigation may include:
-Physicians
-clinics
-Health maintenance organizations
-Hospital emergency rooms
-Public health clinics
-Migrant health clinics

-Asymptomatic persons or mild cases and their contacts should be evaluated
-Suspected cases vs. probable cases

Front 10

5. Count Cases*

Back 10

-Exposure status and disease frequency need to be determined and compared with the appropriate at-risk population

-#cases vs. Size of cases

Front 11

6. Orient the data according to person, place, and time

Person*

Back 11

-Inherent characteristics or people (age, race, sex)
-Acquired characteristics (immunity or marital status)
-Activities (occuaption, leisure, use of medications)
-Conditions (socioeconomic state, access to health case)

Front 12

6. Orient the data according to person, place, and time

Place*

Back 12

-Residence
-Birthplace
-Place of employment
-School district, hospital unit
-Country
-State
-Census tract
-Street address
-Map coordinates

Front 13

6. Orient the data according to person, place, and time

Time*

Back 13

-Epidemic curve

Front 14

7. Classify the epidemic*

Back 14

-Common source
-Propagated
-Mixed

Front 15

Common Source*

Back 15

Starting at a specific point through intermittent or continuous exposure to a source over days, weeks, or years

Front 16

Propagated*

Back 16

Spread gradually from person to person

Front 17

Mixed*

Back 17

Involves a combination of both types of epidemics

Front 18

8. Determine who is at risk of becoming a case*

Back 18

-Clinical, medical, and lab findings need to be confirmed, evaluated, and analyzed for all cases to substantiate the diagnosis
-Classify cases by exposure status

Front 19

9. Analyze the data*

Back 19

-The epidemiologist gathers, complies, tabulated, analyzed, and interprets the findings
-Analysis often involves statistical methods
1. Frequency tables
2. Bivariate analyses
3. Multiple regression

Front 20

10. Formulate hypotheses*

Back 20

Hypotheses should be developed for the following (as a food-borne disease as the example):
-The source of infection
-The vehicle of infection
-The suspect foods
-The mode of tranmission
-The type of pathogen (based on clinical symptoms, incubation periods)
-The time factors in the outbreak and course of the disease
-The place factors in the outbreak
-The person characteristics and factors in the outbreak
-The outside sources of infection
-The tranmission of the disease outside of the study population
-The exposed, unexposed, well and ill cases/individuals

Front 21

11. Test of Hypotheses*

What statistical tests should be employed to evaluate hypotheses?

Back 21

1. T-test
2. Chi-square test
3. F-test

-If established facts or information are lacing to substantiate a hypothesis, then more information should be fathered or the research hypothesis should be rejected

Front 22

12. Develop reports and inform those who need to know*

Back 22

-Narrative of the investigation and review of the course of the epidemic
-Tables, graphs, charts, or any useful and helpful illustrations are presented as well as any pertinent epidemiologic data, tests, lab reports,information, and characteristics
-Addresses the information presented under hypothesis

Front 23

13. Execute control and prevention measure *

Back 23

-Immunization programs (first line of defense against communicable diseases)
-Risk factor prevention (first line of defense against behavioral)
-Behavior change programs

Front 24

14. Administration and planning activities*

Back 24

-Organization
-Coordination
-Communication
-Planning
-Funding
-Allocation

To be most effective you have to be conducted under the government

Front 25

Disease Clusters*

Back 25

-An unusual aggregation, real or perceived*, of health events that are grouped together in time and space and that are reported in a health agency
-It generally occurs in response to the sudden introduction into the human environment of a physical stress, chemical or biological agent, or psychosocial condition

Front 26

Cluster Investigation*

Back 26

-Involves reviewing unusual numbers of health-related states or events, real or perceived, grouped together in time and location
-Confirm reported disease cases
-Identify whether the number of cases is above what is expected (epidemic)
-Identify casual relationships if possible

Front 27

Process to Cluster Investigation*

Back 27

1. Initial response- Preliminary
2. Assessment- Case evaluation
3. Major feasibility study- Occurrence evaluation
4. Etiologic investigation

Front 28

Challenges in cluster investigations

Back 28

Lack of health tracking data may:
-Cause long delays in cluster investigations
-Prevent public health officials from identifying disease trends
-Inhibit the identification of true disease clusters
-Reduce the number of cluster investigations carried out by states, meaning that some clusters go uninvestigated

Front 29

The Steps

Back 29

•Conceptual - Provide a logical progression for the investigation
•Can/should be taken out of order (with caution)

Front 30

Oswego*

Back 30

-Was an outbreak of Gastrointestinal Illness
-Located in village of Lycoming, Oswego County, New York