Oswego Outbreak Investigation

 

Read the “Oswego Outbreak Investigation,” located in the study materials.

In a 750-1,000 word paper, evaluate the situation and present your findings. Include the following:

1. Refer to the “Oswego Outbreak Investigation.” Read the scenario and review the epidemic curve that describes the time of onset of illness. What does this curve tell you regarding the average incubation period, source, and transmission? 
2. Using the incubation range and clinical symptoms, identify potential infectious agents that could be responsible for the outbreak (refer to the study material, “Compendium of Acute Foodborne and Waterborne Diseases”). Provide an explanation for your findings.
3. Why is this considered an outbreak? Discuss the criteria for why it is considered an outbreak.
4. Describe the steps required to investigate an outbreak and apply each step to the Oswego event. Include the relevant information needed for each step to be successful.
5. Discuss the possible routes of transmission for the expected agent.
6. Based on this information, what control measures would you recommend? State a control measure for each prevention level: primary, secondary, and tertiary prevention.

You are required to cite to a minimum of three sources to complete this assignment. Sources must be published within the last 5 years and appropriate for the assignment criteria and public health content.

I have attached two attachments that go along with the assignment. Please review this. 

Rubic_Print_Format

Criteria

10.0%

15.0%

5.0%

5.0%

5.0%

Course Code	Class Code	Assignment Title	Total Points
PUB-540	PUB-540-O500	Oswego Outbreak Investigation	120.0
	Criteria	Percentage	1: Unsatisfactory (0.00%)	2. Less Than Satisfactory (74.00%)	3. Satisfactory (79.00%)	4. Good (87.00%)	5. Excellent (100.00%)	Comments	Points Earned
100.0%
Epi Curve		10.0%	Interpretation of epi curve is omitted.	Interpretation of epi curve is incomplete.	Interpretation of epi curve regarding average incubation period, source, and transmission is summarized. There are minor omissions or inaccuracies.	Interpretation of epi curve regarding average incubation period, source, and transmission is discussed. Some detail is needed for accuracy or clarity. The narrative is adequately supported.	An accurate interpretation of epi curve regarding average incubation period, source, and transmission is presented. The interpretation is clear, well-supported, and informative.
Identification of Potential Infectious Agents	Potential infectious agents are not identified; or, the potential infectious agents identified are not based on incubation range and clinical symptoms.	An attempt is made to use incubation range and clinical symptoms to identify potential infectious agents that could be responsible for the outbreak. The narrative is incomplete.	Incubation range and clinical symptoms are generally applied to identify potential infectious agents that could be responsible for the outbreak. An explanation is summarized. Some support is needed.	Incubation range and clinical symptoms are applied to identify potential infectious agents that could be responsible for the outbreak. The explanation is adequate. Some detail is needed for accuracy or clarity.	Incubation range and clinical symptoms are correctly applied to identify potential infectious agents that could be responsible for the outbreak. The explanation for the findings is well-supported.
Oswego Outbreak (Evidence for outbreak, steps required to investigate, application of steps to Oswego event)	20.0%	The discussion on the Oswego event is omitted.	Qualifying criteria for why Oswego are considered an outbreak, steps required to investigate an outbreak, and application of these steps to the Oswego event are only partially discussed.	Qualifying criteria for why Oswego are considered an outbreak, steps required to investigate an outbreak, and application of these steps to the Oswego event are summarized. Relevant information needed for each step to be successful is generally used. There are minor omissions or inaccuracies. Some support is needed.	Qualifying criteria for why Oswego is considered an outbreak, steps required to investigate an outbreak, and application of these steps to the Oswego event are discussed and explained. Relevant information needed for each step to be successful is discussed. Some detail is needed for accuracy or clarity.	A clear explanation, including qualifying criteria for why Oswego is considered an outbreak, steps required to investigate an outbreak, and application of these steps to the Oswego event is accurate and detailed. Relevant information needed for each step to be successful is thoroughly discussed. The narrative is organized and well-supported.
Routes of Transmission for Agent		1			5.0%	Possible routes of transmission for the expected agent are omitted.	Possible routes of transmission for the expected agent are partially discussed.	Possible routes of transmission for the expected agent are summarized. There are minor omissions or inaccuracies.	Possible routes of transmission for the expected agent are discussed. Some detail is needed for accuracy or clarity.	Possible routes of transmission for the expected agent are accurate and thoroughly discussed.
Recommended Control Measures for Prevention Levels	Control measures are omitted.	Control measures are incomplete.	A control measure for each prevention level is summarized. The control measures are generally based on findings. There are minor omissions or inaccuracies.	A control measure for each prevention level is discussed. The control measures are based on findings. Some detail is needed for accuracy or clarity.	A control measure for each prevention level is detailed and well supported.
Thesis Development and Purpose	7.0%	Paper lacks any discernible overall purpose or organizing claim.	Thesis is insufficiently developed or vague. Purpose is not clear.	Thesis is apparent and appropriate to purpose.	Thesis is clear and forecasts the development of the paper. Thesis is descriptive and reflective of the arguments and appropriate to the purpose.	Thesis is comprehensive and contains the essence of the paper. Thesis statement makes the purpose of the paper clear.
Argument Logic and Construction	8.0%	Statement of purpose is not justified by the conclusion. The conclusion does not support the claim made. Argument is incoherent and uses noncredible sources.	Sufficient justification of claims is lacking. Argument lacks consistent unity. There are obvious flaws in the logic. Some sources have questionable credibility.	Argument is orderly, but may have a few inconsistencies. The argument presents minimal justification of claims. Argument logically, but not thoroughly, supports the purpose. Sources used are credible. Introduction and conclusion bracket the thesis.	Argument shows logical progressions. Techniques of argumentation are evident. There is a smooth progression of claims from introduction to conclusion. Most sources are authoritative.	Clear and convincing argument that presents a persuasive claim in a distinctive and compelling manner. All sources are authoritative.
Mechanics of Writing (includes spelling, punctuation, grammar, language use)	Surface errors are pervasive enough that they impede communication of meaning. Inappropriate word choice or sentence construction is used.	Frequent and repetitive mechanical errors distract the reader. Inconsistencies in language choice (register) or word choice are present. Sentence structure is correct but not varied.	Some mechanical errors or typos are present, but they are not overly distracting to the reader. Correct and varied sentence structure and audience-appropriate language are employed.	Prose is largely free of mechanical errors, although a few may be present. The writer uses a variety of effective sentence structures and figures of speech.	Writer is clearly in command of standard, written, academic English.
Paper Format (use of appropriate style for the major and assignment)	Template is not used appropriately or documentation format is rarely followed correctly.	Appropriate template is used, but some elements are missing or mistaken. A lack of control with formatting is apparent.	Appropriate template is used. Formatting is correct, although some minor errors may be present.	Appropriate template is fully used. There are virtually no errors in formatting style.	All format elements are correct.
Documentation of Sources (citations, footnotes, references, bibliography, etc., as appropriate to assignment and style)	Sources are not documented.	Documentation of sources is inconsistent or incorrect, as appropriate to assignment and style, with numerous formatting errors.	Sources are documented, as appropriate to assignment and style, although some formatting errors may be present.	Sources are documented, as appropriate to assignment and style, and format is mostly correct.	Sources are completely and correctly documented, as appropriate to assignment and style, and format is free of error.
Total Weightage	100%

Oswego Outbreak Investigation

NOTE: The following resource was prepared for class use by replicating portions of the Centers for Disease Control and Prevention’s (CDC), “Oswego – An Outbreak of Gastrointestinal Illness Following a Church Supper: Student Guide” (CDC, n.d.), except for the “Questions” section, with the understanding that the CDC document is in the public domain and available for educational use.

Background:

On April

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9, 1940, the local health officer in the village of Lycoming, Oswego County, New York, reported the occurrence of an outbreak of acute gastrointestinal illness to the District Health Officer in Syracuse. Dr. A. M. Rubin, epidemiologist-in-training, was assigned to conduct an investigation. When Dr. Rubin arrived in the field, he learned from the health officer that all persons known to be ill had attended a church supper held on the previous evening, April 18. Family members who did not attend the church supper did not become ill. Accordingly, Dr. Rubin focused the investigation on the supper. He completed interviews with 75 of the 80 persons known to have attended, collecting information about the occurrence and time of onset of symptoms, and foods consumed. Of the 75 persons interviewed, 46 persons reported gastrointestinal illness.

Clinical Description:

The onset of illness in all cases was acute, characterized chiefly by nausea, vomiting, diarrhea, and abdominal pain. None of the ill persons reported having an elevated temperature; all recovered within 24 to

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0 hours. Approximately 20% of the ill persons visited physicians. No fecal specimens were obtained for bacteriologic examination.

Description of the Supper:

The supper was held in the basement of the village church. Foods were contributed by numerous members of the congregation. The supper began at 6:00 p.m. and continued until 11:00 p.m. Food was spread out on a table and consumed over a period of several hours. Data regarding onset of illness and food eaten or water drunk by each of the 75 persons interviewed [are provided in the Excel “Oswego Line Listing Workbook” (CDC, n.d.)]. The approximate time of eating supper was collected for only about half the persons who had gastrointestinal illness.

Conclusion:

The following is quoted verbatim from the report prepared by Dr. Rubin:

The ice cream was prepared by the Petrie sisters as follows:

On the afternoon of April 17 raw milk from the Petrie farm at Lycoming was brought to boil over a water bath, sugar and eggs were then added and a little flour to add body to the mix. The chocolate and vanilla ice cream were prepared separately. Hershey’s chocolate was necessarily added to the chocolate mix. At 6 p.m. the two mixes were taken in covered containers to the church basement and allowed to stand overnight. They were presumably not touched by anyone during this period.

On the morning of April 18, Mr. Coe added five ounces of vanilla and two cans of condensed milk to the vanilla mix, and three ounces of vanilla and one can of condensed milk to the chocolate mix. Then the vanilla ice cream was transferred to a freezing can and placed in an electrical freezer for 20 minutes, after which the vanilla ice cream was removed from the freezer can and packed into another can which had been previously washed with boiling water. Then the chocolate mix was put into the freezer can which had been rinsed out with tap water and allowed to freeze for 20 minutes. At the conclusion of this both cans were covered and placed in large wooden receptacles which were packed with ice. As noted, the chocolate ice cream remained in the one freezer can.

All handlers of the ice cream were examined. No external lesions or upper respiratory infections were noted. Nose and throat cultures were taken from two individuals who prepared the ice cream.

Bacteriological examinations were made by the Division of Laboratories and Research, Albany, on both ice creams. Their report is as follows: “Large numbers of Staphylococcus aureus and albus were found in the specimen of vanilla ice cream. Only a few staphylococci were demonstrated in the chocolate ice cream.”

Report of the nose and throat cultures of the Petries who prepared the ice cream read as follows: “Staphylococcus aureus and hemolytic streptococci were isolated from nose culture and Staphylococcus albus from throat culture of Grace Petrie. Staphylococcus albus was isolated from the nose culture of Marian Petrie. The hemolytic streptococci were not of the type usually associated with infections in man.”

Discussion as to Source: The source of bacterial contamination of the vanilla ice cream is not clear. Whatever the method of the introduction of the staphylococci, it appears reasonable to assume it must have occurred between the evening of April 17 and the morning of April 18. No reason for contamination peculiar to the vanilla ice cream is known.

In dispensing the ice creams, the same scooper was used. It is therefore not unlikely to assume that some contamination to the chocolate ice cream occurred in this way. This would appear to be the most plausible explanation for the illness in the three individuals who did not eat the vanilla ice cream.

Control Measures: On May 19, all remaining ice cream was condemned. All other food at the church supper had been consumed.

Conclusions: An attack of gastroenteritis occurred following a church supper at Lycoming. The cause of the outbreak was contaminated vanilla ice cream. The method of contamination of ice cream is not clearly understood. Whether the positive Staphylococcus nose and throat cultures occurring in the Petrie family had anything to do with the contamination is a matter of conjecture.

Note: Patient #52 was a child who while watching the freezing procedure was given a dish of vanilla ice cream at 11:00 a.m. on April 18.

Epi Curve

Addendum:

Certain laboratory techniques not available at the time of this investigation might prove very useful in the analysis of a similar epidemic today. These are phage typing, which can be done at CDC, and identification of staphylococcal enterotoxin in food by immunodiffusion or by enzyme-linked immunosorbent assay (ELISA), which is available through the Food and Drug Administration (FDA).

One would expect the phage types of staphylococci isolated from Grace Petrie’s nose and the vanilla ice cream and vomitus or stool samples from ill persons associated with the church supper to be identical had she been the source of contamination. Distinctly different phage types would mitigate against her as the source (although differences might be observed as a chance phenomenon of sampling error) and suggest the need for further investigation, such as cultures of others who might have been in contact with the ice cream in preparation or consideration of the possibility that contamination occurred from using a cow with mastitis and that the only milk boiled was that used to prepare chocolate ice cream. If the contaminated food had been heated sufficiently to destroy staphylococcal organisms but not toxin, analysis for toxin (with the addition of urea) would still permit detection of the cause of the epidemic. A Gram stain might also detect the presence of nonviable staphylococci in contaminated food.

Reference

Centers for Disease Control and Prevention. (n.d.). Oswego – An outbreak of gastrointestinal illness following a church supper: Student guide (Case No. 401-303). https://www.cdc.gov/eis/casestudies/xoswego.401-303.student

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