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Questions and Answers
What was the total number of people who developed botulism after eating tuna sandwiches?
What was the total number of people who developed botulism after eating tuna sandwiches?
What is the proportion of individuals who developed botulism after consuming tuna sandwiches?
What is the proportion of individuals who developed botulism after consuming tuna sandwiches?
What does the relative risk indicate regarding the likelihood of developing botulism when consuming tuna sandwiches?
What does the relative risk indicate regarding the likelihood of developing botulism when consuming tuna sandwiches?
How many people consumed tuna sandwiches in total?
How many people consumed tuna sandwiches in total?
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What percentage of people who did not eat tuna sandwiches developed botulism?
What percentage of people who did not eat tuna sandwiches developed botulism?
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What is the first step in an outbreak investigation?
What is the first step in an outbreak investigation?
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What does the case definition for hepatitis A include?
What does the case definition for hepatitis A include?
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Which type of surveillance involves actively searching for cases?
Which type of surveillance involves actively searching for cases?
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What is the purpose of generating hypotheses in an outbreak investigation?
What is the purpose of generating hypotheses in an outbreak investigation?
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Which of the following steps is NOT part of the outbreak investigation process?
Which of the following steps is NOT part of the outbreak investigation process?
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What does the case definition specifically exclude in the context of this hepatitis A outbreak?
What does the case definition specifically exclude in the context of this hepatitis A outbreak?
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What is the goal of the 'Search for cases' step?
What is the goal of the 'Search for cases' step?
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What is the final step in the outbreak investigation process?
What is the final step in the outbreak investigation process?
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What is the purpose of identifying the stage of an epidemic?
What is the purpose of identifying the stage of an epidemic?
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What can outliers in an epidemic curve indicate?
What can outliers in an epidemic curve indicate?
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What is the first step in conducting an outbreak investigation?
What is the first step in conducting an outbreak investigation?
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What is crucial for estimating the probable time of exposure during an outbreak?
What is crucial for estimating the probable time of exposure during an outbreak?
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In the context of outbreak investigations, what does defining a case involve?
In the context of outbreak investigations, what does defining a case involve?
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What type of outbreak was associated with crabcakes at a church fundraiser in Maryland in 2003?
What type of outbreak was associated with crabcakes at a church fundraiser in Maryland in 2003?
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Why is it necessary to communicate findings during an outbreak investigation?
Why is it necessary to communicate findings during an outbreak investigation?
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What was linked to an international outbreak of hepatitis A in 2013?
What was linked to an international outbreak of hepatitis A in 2013?
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What defines an outbreak in terms of occurrence?
What defines an outbreak in terms of occurrence?
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What is NOT a reason for investigating outbreaks?
What is NOT a reason for investigating outbreaks?
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Which pathogen-related outbreak has been recorded the highest number since March 2020?
Which pathogen-related outbreak has been recorded the highest number since March 2020?
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In the context of outbreak investigation, what is the first step?
In the context of outbreak investigation, what is the first step?
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What is involved in testing hypotheses during an outbreak investigation?
What is involved in testing hypotheses during an outbreak investigation?
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Which of the following is a key outcome of effective outbreak management?
Which of the following is a key outcome of effective outbreak management?
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When defining a case in outbreak investigation, which factor is considered least important?
When defining a case in outbreak investigation, which factor is considered least important?
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Which statement about managing outbreaks is most accurate?
Which statement about managing outbreaks is most accurate?
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What is the primary purpose of defining a case in outbreak investigations?
What is the primary purpose of defining a case in outbreak investigations?
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What is the first step in an outbreak investigation?
What is the first step in an outbreak investigation?
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Which statement about the communication of findings in an outbreak investigation is correct?
Which statement about the communication of findings in an outbreak investigation is correct?
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Which of the following describes a necessary component of generating hypotheses during an outbreak investigation?
Which of the following describes a necessary component of generating hypotheses during an outbreak investigation?
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What is a critical part of confirming a diagnosis during an outbreak investigation?
What is a critical part of confirming a diagnosis during an outbreak investigation?
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When creating a case definition, why must it avoid including exposures or risk factors?
When creating a case definition, why must it avoid including exposures or risk factors?
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In the scenario of hepatitis A cases among men who have sex with men, which aspect should the case definition include?
In the scenario of hepatitis A cases among men who have sex with men, which aspect should the case definition include?
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What type of findings are primarily used in analytical epidemiology to test hypotheses?
What type of findings are primarily used in analytical epidemiology to test hypotheses?
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Which component is essential for establishing the existence of a real outbreak?
Which component is essential for establishing the existence of a real outbreak?
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What is one common artifact that may falsely indicate an outbreak?
What is one common artifact that may falsely indicate an outbreak?
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Which member of the Outbreak Control Team primarily coordinates outbreak management activities?
Which member of the Outbreak Control Team primarily coordinates outbreak management activities?
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What is a primary goal of using analytical epidemiology during an outbreak investigation?
What is a primary goal of using analytical epidemiology during an outbreak investigation?
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Which step immediately follows the confirmation of a diagnosis in the outbreak investigation process?
Which step immediately follows the confirmation of a diagnosis in the outbreak investigation process?
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What is the role of environmental health officers in an outbreak investigation?
What is the role of environmental health officers in an outbreak investigation?
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Which phenomenon can indicate an increase in reported cases during an outbreak investigation?
Which phenomenon can indicate an increase in reported cases during an outbreak investigation?
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In the context of an outbreak, why is it important to communicate findings effectively?
In the context of an outbreak, why is it important to communicate findings effectively?
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Which study design is most suitable when the affected population is known and a complete list of individuals is available?
Which study design is most suitable when the affected population is known and a complete list of individuals is available?
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What is the initial step in confirming a diagnosis during an outbreak investigation?
What is the initial step in confirming a diagnosis during an outbreak investigation?
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Which method is used to identify identical microbiological isolates among cases during an outbreak investigation?
Which method is used to identify identical microbiological isolates among cases during an outbreak investigation?
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What is a critical reason for conducting environmental investigations in an outbreak?
What is a critical reason for conducting environmental investigations in an outbreak?
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In the context of outbreak investigations, which step involves communicating findings to relevant stakeholders?
In the context of outbreak investigations, which step involves communicating findings to relevant stakeholders?
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Why is it important to generate hypotheses using descriptive findings in an outbreak investigation?
Why is it important to generate hypotheses using descriptive findings in an outbreak investigation?
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What is the purpose of conducting additional investigations such as anthropological studies during an outbreak?
What is the purpose of conducting additional investigations such as anthropological studies during an outbreak?
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Which epidemiological approach is primarily used to assess disease status and exposures when the affected population needs to be contacted?
Which epidemiological approach is primarily used to assess disease status and exposures when the affected population needs to be contacted?
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What can be inferred from the presence of outliers in an epidemic curve?
What can be inferred from the presence of outliers in an epidemic curve?
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During the evaluation stage of an outbreak investigation, what is the primary focus?
During the evaluation stage of an outbreak investigation, what is the primary focus?
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What is the role of establishing the existence of a real outbreak in the investigation process?
What is the role of establishing the existence of a real outbreak in the investigation process?
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What is a significant consequence of poorly defining a case during an outbreak investigation?
What is a significant consequence of poorly defining a case during an outbreak investigation?
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In the context of epidemic curves, what is primarily evaluated when identifying the stage of an epidemic?
In the context of epidemic curves, what is primarily evaluated when identifying the stage of an epidemic?
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Which factor is least relevant when estimating the probable time of exposure in an outbreak?
Which factor is least relevant when estimating the probable time of exposure in an outbreak?
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What is the expected outcome if control measures implemented during an epidemic investigation are deemed ineffective?
What is the expected outcome if control measures implemented during an epidemic investigation are deemed ineffective?
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What type of outbreak is associated with the investigation of hepatitis A linked to frozen berries?
What type of outbreak is associated with the investigation of hepatitis A linked to frozen berries?
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What is the primary goal of using descriptive epidemiology in an outbreak investigation?
What is the primary goal of using descriptive epidemiology in an outbreak investigation?
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Which aspect is crucial for identifying common exposures in open-ended questionnaires?
Which aspect is crucial for identifying common exposures in open-ended questionnaires?
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What do spot maps primarily illustrate in the context of outbreak investigations?
What do spot maps primarily illustrate in the context of outbreak investigations?
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How can epidemic curves be useful in understanding an outbreak?
How can epidemic curves be useful in understanding an outbreak?
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In the context of generating hypotheses, which characteristic is considered least informative?
In the context of generating hypotheses, which characteristic is considered least informative?
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What is the significance of examining the time component in an outbreak analysis?
What is the significance of examining the time component in an outbreak analysis?
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Which factor is essential when describing the 'place' aspect of outbreak cases?
Which factor is essential when describing the 'place' aspect of outbreak cases?
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When utilizing questionnaires in hypothesis generation, what type of exposure should be prioritized for analysis?
When utilizing questionnaires in hypothesis generation, what type of exposure should be prioritized for analysis?
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What is the main goal of the hypothesis testing step in an outbreak investigation?
What is the main goal of the hypothesis testing step in an outbreak investigation?
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Which of the following best describes a significant aspect of drawing conclusions in outbreak investigations?
Which of the following best describes a significant aspect of drawing conclusions in outbreak investigations?
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During which step of an outbreak investigation is it most crucial to communicate findings effectively?
During which step of an outbreak investigation is it most crucial to communicate findings effectively?
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In the context of outbreak investigation, how does analytical epidemiology primarily contribute?
In the context of outbreak investigation, how does analytical epidemiology primarily contribute?
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What is the primary purpose behind executing control and prevention measures in an outbreak investigation?
What is the primary purpose behind executing control and prevention measures in an outbreak investigation?
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Which statistical concept is crucial to determine when drawing conclusions from an outbreak investigation?
Which statistical concept is crucial to determine when drawing conclusions from an outbreak investigation?
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What is a key consideration when defining a case during an outbreak investigation?
What is a key consideration when defining a case during an outbreak investigation?
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Which step of an outbreak investigation is critical for confirming the diagnosis of affected individuals?
Which step of an outbreak investigation is critical for confirming the diagnosis of affected individuals?
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Study Notes
What is an outbreak?
- More cases of an illness than expected
- Occurs within a specific time period, place and among specific group of people
Why Investigate Outbreaks?
- Important cause of illness and death
- Outbreaks can be controlled
- Provide insight into what happened and why
- Prevent future outbreaks
- Improve surveillance and outbreak detection
Importance of Outbreaks
- Ireland 2019: 646 outbreaks leading to 5852 outbreak-associated cases, mainly gastrointestinal/respiratory pathogens
- COVID-19 Outbreaks: 27,610 outbreaks since March 2020 (as of May 18th 2024)
Steps of an outbreak investigation
- Establish the existence of a real outbreak
- Confirm the diagnosis
- Define a case
- Search for cases
- Generate hypotheses using descriptive findings
- Test hypotheses using analytical epidemiology
- Conduct additional investigations
- Draw conclusions
- Communicate findings
- Execute control and prevention measures
Confirming the diagnosis
- Two-stage process:
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Clarify syndrome and identify diagnoses:
- Communicate with clinicians, specialists
- Examine frequency of symptoms among cases
- Identify age groups affected
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Confirm diagnosis with laboratory tests:
- Discuss best tests with laboratory and clinicians
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Clarify syndrome and identify diagnoses:
Defining a case
- Clinical and laboratory criteria + time, place and person restrictions
- Time (e.g. illness onset from specific date)
- Place (e.g. residents of a region, event attendees)
- Person (clinical/lab criteria & potentially age, sex, ethnicity)
- Apply to everyone under investigation
- Ensure case definition is not too restrictive to find all cases
- Case definition should not include suspected exposure or risk factor
Example Outbreak Case Definition: Unwell wedding guests
- Attended wedding at hotel X on 25 June 2010
- Reported illness with diarrhoea or vomiting
- Illness onset between 26 June 2010 and 5 July 2010
Searching for cases
- Starts with case definition and population at risk
- Uniform strategy to search for cases
- Passive surveillance: Usual surveillance methods
-
Active surveillance:
- Alert clinicians, microbiologists, known members of at-risk population
- Direct search in medical records
- Snowball method
- Community/public search: Door-to-door, media alerts
Epidemic Curves
- Point Source: Everyone exposed at single point in time, curve shows rapid rise then decline
- Continuing Source: Multiple exposures, curve shows plateau or multiple peaks.
Testing hypotheses
- Relative risk (RR): Measures the likelihood of developing an outcome in the exposed group compared to the unexposed group
- Attack rate (AR): Proportion of people who develop illness in a population over a period of time.
Food specific AR example
- The funeral party had 100 people who ate sandwiches. Sandwiches included canned tuna, canned crab, salmon, turkey, and salad.
- 13 people developed botulism based on this data, the AR is 13/100 or 13%.
Food specific RR example
- RR = AR in those who ate particular food / AR in those who did not eat the particular food
-
Example: RR of Botulism in those who ate tuna:
- AR of botulism in tuna eaters: 10/30 or 33%
- AR of botulism in non-tuna eaters: 3/70 or 4.3%
- RR of botulism for tuna eaters = (10/30) / (3/70) = 7.7
- Conclusion: You were nearly eight times as likely to develop botulism if you ate a tuna sandwich than if you did not.
Outbreak Investigation Steps
-
Establish the existence of an outbreak: Identify a real outbreak with data gathered from systematic surveillance, detection of additional cases during investigations, alerts from physicians, public reports, and media reports.
-
Confirm the diagnosis: Ensure that reported cases are truly what they are classified as.
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Define a case: Establish a specific case definition through criteria that clearly defines the criteria for an outbreak/illness.
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Search for cases: Actively find potential cases through contacting those who may be affected and identify their exposure.
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Generate hypotheses: Use descriptive epidemiological information like time, place, and person to identify characteristics and potential causes of an outbreak.
- Time: The epidemic curve can visualize the size of the outbreak over time, show patterns, and identify the stage of the outbreak.
- Place: Visualizing the location of cases through maps can show the geographic extent of the outbreak and identify potential clusters or patterns.
- Person: Identify case characteristics, potential exposures (diet, occupation, leisure activities, etc.) and the date and location of potential exposure.
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Test hypotheses: Analyze data with epidemiological studies to evaluate potential exposures and their association to illness.
- Cohort: When the affected population is known and complete, analyze it to assess disease status and possible exposure.
- Case control: When the affected population is not well defined, a comparison group is selected to asses exposure.
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Conduct additional investigations: Conduct laboratory studies, environmental, anthropological and veterinarian investigations as necessary.
- Laboratory studies: Microbiological typing to identify identical isolates in cases and potential sources.
- Environmental: Test the environment (water, air quality, etc.) to identify the potential source of contamination.
- Anthropological: Study culture, practices, social behaviors to identify potential causes.
- Veterinarian: Study animals in zoonotic cases to identify whether animals could be a potential source of contamination.
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Draw conclusions: Interpret the collected data and determine if the suspected exposure is associated with illness.
- Causality? Can the exposure be conclusively linked to the illness?
- Dose response? Does increased exposure result in stronger associations?
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Communicate findings: Share information about the investigation through reports, papers, and websites.
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Control and prevention measures: Implement control measures to prevent future outbreaks from happening.
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Description
This quiz explores the fundamentals of outbreak investigations, including definitions, importance, and the steps necessary for effective investigation. Understand how outbreaks are defined, why they are critical to public health, and the systematic approach to manage and prevent future outbreaks.