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30 Cards in this Set
- Front
- Back
What is field epidemiology?*
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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 |
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What are the three important ways that field investigations involving acute problems may differ from conventional epidemiologic studies?
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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 |
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How many steps are there in field investigation?
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14
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1. Establish the existence of an epidemic (or outbreak)*
Why are attack rates an appropriate statistics for investigating disease outbreaks? |
Because they describe rapidly occuring new cases of disease in a well-defined population over a limited time period
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1. Establish the existence of an epidemic (or outbreak)*
What are attack rates usually calculated by? |
By person characteristics (Ex. age, sex, race, ethnicity, and occupation) in order to identify high-risk groups
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2. Confirm the diagonosis*
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-Assessment of the cinical findings should be done to assure correctness and reliablity of the findings
-Clinical diagnosis by appropriately trained individuals -Laboratory diagnosis |
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3. Establish criteria for case identification*
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-Standard clinical criteria (what)
-Loose case definition vs. sstrict case definition -A case may be further characterized by: who, when, where |
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What is the deciding factor for loose case definition vs. strict case definition*
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Time
-loose case: spreading at a fast rate -strict case: spreading at a slower rate, not impacting population as much |
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4. Search for missing cases*
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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 |
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5. Count Cases*
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-Exposure status and disease frequency need to be determined and compared with the appropriate at-risk population
-#cases vs. Size of cases |
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6. Orient the data according to person, place, and time
Person* |
-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) |
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6. Orient the data according to person, place, and time
Place* |
-Residence
-Birthplace -Place of employment -School district, hospital unit -Country -State -Census tract -Street address -Map coordinates |
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6. Orient the data according to person, place, and time
Time* |
-Epidemic curve
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7. Classify the epidemic*
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-Common source
-Propagated -Mixed |
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Common Source*
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Starting at a specific point through intermittent or continuous exposure to a source over days, weeks, or years
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Propagated*
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Spread gradually from person to person
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Mixed*
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Involves a combination of both types of epidemics
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8. Determine who is at risk of becoming a case*
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-Clinical, medical, and lab findings need to be confirmed, evaluated, and analyzed for all cases to substantiate the diagnosis
-Classify cases by exposure status |
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9. Analyze the data*
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-The epidemiologist gathers, complies, tabulated, analyzed, and interprets the findings
-Analysis often involves statistical methods 1. Frequency tables 2. Bivariate analyses 3. Multiple regression |
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10. Formulate hypotheses*
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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 |
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11. Test of Hypotheses*
What statistical tests should be employed to evaluate hypotheses? |
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 |
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12. Develop reports and inform those who need to know*
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-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 |
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13. Execute control and prevention measure *
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-Immunization programs (first line of defense against communicable diseases)
-Risk factor prevention (first line of defense against behavioral) -Behavior change programs |
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14. Administration and planning activities*
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-Organization
-Coordination -Communication -Planning -Funding -Allocation To be most effective you have to be conducted under the government |
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Disease Clusters*
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-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 |
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Cluster Investigation*
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-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 |
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Process to Cluster Investigation*
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1. Initial response- Preliminary
2. Assessment- Case evaluation 3. Major feasibility study- Occurrence evaluation 4. Etiologic investigation |
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Challenges in cluster investigations
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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 |
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The Steps
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•Conceptual - Provide a logical progression for the investigation
•Can/should be taken out of order (with caution) |
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Oswego*
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-Was an outbreak of Gastrointestinal Illness
-Located in village of Lycoming, Oswego County, New York |