PRINCIPLES OF EPIDEMIOLOGY
TOPIC: Oswego Outbreak Case Study
Read the "Oswego Outbreak Investigation," located in the Topic Materials.
Part 1
Complete the following:
Using the line listing in the Excel "Oswego Line Listing Workbook," calculate the attack rate ratios for each food item using the table in the Excel "Oswego Attack Rate Table." Create a separate 2x2 table for the food item you think is responsible for the outbreak and interpret the attack rate ratio for this food item. Refer to the "Creating a 2x2 Contingency Table" resource for guidance.
Using the line listing in Excel "Oswego Line Listing Workbook," construct an epidemic curve by the time of onset of illness. What does this curve tell you regarding the average incubation period, source, and transmission?
Using the incubation range and clinical symptoms, identify potential infectious agents that could be responsible for the outbreak (refer to the Topic Material, "Compendium of Acute Foodborne and Waterborne Diseases"). Discuss your rationale.
Part 2
In a 500-750 word paper, evaluate the situation and present your findings. Including the following:
Does this case meet the definition of an "outbreak?" Why or why not?
Identify the steps required to investigate an outbreak. How did these steps help in investigating the Oswego event? Include the relevant information needed for each step to be successful.
Discuss the possible routes of transmission for the expected agent.
Based on this information, what control measures would you recommend? State whether they are primary, secondary, or tertiary prevention strategies.
General Requirements
Prepare this assignment according to the guidelines found in the APA Style Guide.
You are required to submit this assignment to LopesWrite.
STUDY MATERIALS
Read Chapters 3-5 and 18 in Gordis Epidemiology.
Read "Types of Surveillance," located on the London School of Hygiene and Tropical Medicine website. URL:http://conflict.lshtm.ac.uk/page_75.htm
Read "WHO Report on Global Surveillance of Epidemic-Prone Infectious Diseases - Introduction," located on the World Health Organization (WHO) website. URL: https://www.who.int/csr/resources/publications/introduction/en/
Read "CDC 24-7 Fact of the Week," located on the Centers for Disease Control and Prevention (CDC) website. URL:https://www.cdc.gov/about/facts/index.html?CDC_AA_refVal=https%3A%2F%2Fwww.cdc.gov%2Fabout%2Ffacts%2Fcdcfastfacts%2Fsurveillance.html
Read "Two by Two Tables," by Sullivan, Dean, and Pezzullo, from OpenEpi: Open Source Epidemiologic Statistics for Public Health (2013), located on the OpenEpi website. URL: http://www.openepi.com/TwobyTwo/TwobyTwo.htm
Read "Goodness of Measurement: Reliability and Validity," by Bajpai and Bajpai, from International Journal of Medical Science and Public Health (2014). URL: https://www.ejmanager.com/mnstemps/67/67-1380953319.pdf
Use the "Compendium of Acute Foodborne and Waterborne Diseases," located on the Centers for Disease Control and Prevention (CDC) website, to assist in completing the Oswego Outbreak Case History assignment. URL: https://www.cdc.gov/eis/casestudies/xoswego.401.303.compendium.pdf
View "How to Create an Epidemic Curve," by Martin (2016), located on the YouTube website. URL: https://www.youtube.com/watch?v=dn84ezAzV4k
View "Know How to Interpret an Epidemic Curve?" by Martin (2017), located on the YouTube website. URL: https://www.youtube.com/watch?v=7SM4PN7Yg1s
Explore the National Notifiable Diseases Surveillance System (NNDSS) page of the Centers for Disease Control and Prevention (CDC) website. URL: https://wwwn.cdc.gov/nndss/
Explore Public Health Surveillance and Data page of the Centers for Disease Control and Prevention (CDC) website. URL: https://www.cdc.gov/surveillance/
Creating a 2x2 Contingency Table
Creating a 2x2 contingency table is very useful in calculating a variety of public health measurements, including sensitivity and specificity, negative and positive predictive value, risk ratios, attack rate ratios, and odds ratios.
A 2x2 table is actually a 3x3 table when you include the rows and columns for the totals. If you are setting up a table to measure the sensitivity and specificity of a test or its negative and positive predictive values, you should put the test results on the y-axis (rows) and the actual presence of disease on the x-axis (columns).
Disease
No Disease
Total
Test (+)
(a)
(b)
a + b
Test (-)
(c)
(d)
c + d
Total
a + c
b + d
a + b + c + d
The highlighted section is where you will enter the data for each corresponding cell. You can set up the table switching the rows and columns but you will generally see them set up in this format with test results on the y-axis and disease on the x-axis.
Setting up a table to measure the association of a risk factor or exposure is similar, with the outcome or disease on the x-axis and the presence of the risk factor or exposure on the y-axis.
Disease
No Disease
Total
Exposure (+)
(a)
(b)
a + b
Exposure (-)
(c)
(d)
c + d
Total
a + c
b + d
a + b + c + d
Note: You can set up the table differently but you will need to be cognizant of which numbers you are putting in your numerator and denominator for the measure you are calculating. For example:
Exposure (+)
Exposure (-)
Total
No Disease
(b)
(d)
b + d
Disease
(a)
(c)
a + c
Total
a + b
b + c
a + b + c + d