Food Items Served Number of persons who ATE specified food Ill Baked Ham Spinach Mashed Potato Cabbage Salad Jello Rolls Brown Bread Milk Coffee Water Cakes Ice Cream, Vanilla Ice Cream, Chocolate Fruit Salad Not Ill Total Percent Ill (Attack rate) Number of persons did NOT eat specified food Ill Not Ill Total of persons did NOT eat specified food Percent Ill (Attack rate) Attack Rate ratio or Relative Risk PART I - Background On April 19, 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, 48 persons reported gastrointestinal illness. Question 1: Do you believe this is an outbreak? Explain your answer. Question 2: Provide the steps of an outbreak investigation. Refer to the Steps of an Epi Investigation PPT in the Ch. 1 folder. 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 30 hours. Approximately 20% of the ill persons visited physicians. No fecal specimens were obtained for bacteriologic examination. Question 3: From the Compendium of Acute Foodborne & Waterborne Diseases handout, list all the agents that fit at this point (symptoms and time to recovery) in the differential diagnosis of this outbreak of gastrointestinal illness. You must list at least 5 agents. The investigators suspected that this was a vehicle-borne outbreak, with food as the vehicle. Question 4: In epidemiologic terminology, what is a vehicle and give some examples? What is a vector and give some examples? (see Ch. 12) Question 5: If you were to administer a questionnaire to the church supper participants, what questions would you ask? List at least 8 questions other than demographics (age, sex, race). Dr. Rubin put his data into a line listing. Question 6: What is a line listing? What is the value of a line listing? (2 different line listings are provided on the following pages. Explain the differences between the first line listing and the 2nd improved line listing.) PART II 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 attached line listing. The approximate time of eating supper was collected for only about half the persons who had gastrointestinal illness. Question 7: What is the value of an epidemic curve? Use what you learned from the 1st CDC Module to help you answer this question. Question 8: Use Excel to construct an Epi Curve by time of onset of illness (use either 15 minute or ½ hr increments on the x-axis and include appropriate labels and title). What does this graph tell you? Question 9: Are there any cases for which the times of onset are inconsistent with the general experience (called ‘outliers’)? If so, provide information on them and how they might be explained? Question 10: Using the information from the line listing, provide the following descriptive information on the cases (ill persons). How many of the cases were female? How many were male? Give the range of ages and the overall mean age. What was the mean age for female cases? Mean age for male cases? Line listing from investigation of outbreak of gastroenteritis, Oswego, New York, 1940 TIME OF MEAL unk 8:00 PM 6:30 PM 6:30 PM unk 7:30 PM 7:30 PM 7:30 PM 10:00 PM 7:00 PM ILL N Y Y Y N Y Y Y Y Y M F F M M F F M M F unk 8:00 PM unk 7:30 PM unk unk unk unk unk unk N Y N Y N Y Y Y N Y 13 7 64 3 65 59 15 62 37 17 F M M M F F F M F M 10:00 PM unk unk unk unk unk 10:00 PM unk unk 10:00 PM 35 15 50 40 35 35 36 57 16 68 M M F M F F M F F M unk 10:00 PM 10:00 PM unk unk unk unk unk 10:00 PM unk ID 1 2 3 4 5 6 7 8 9 10 AGE SEX 11 M 52 F 65 M 59 F 13 F 63 F 70 M 40 F 15 F 33 F 11 12 13 14 15 16 17 18 19 20 65 38 62 10 25 32 62 36 11 33 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 DATE OF ONSET TIME OF ONSET 4/19 4/19 4/19 12:30 AM 12:30 AM 12:30 AM 4/18 4/18 4/19 4/19 4/18 10:30 PM 10:30 PM 2:00 AM 1:00 AM 11:00 PM 4/19 12:00 AM* 4/19 2:00 AM 4/19 4/19 4/18 10:30 AM 12:30 AM 10:15 PM 4/18 10:00 PM Y Y N Y N Y Y N Y N 4/19 4/18 1:00 AM 11:00 PM 4/18 9:45 PM 4/18 4/19 9:45 PM 1:00 AM 4/18 11:00 PM Y Y Y N N Y N Y Y Y 4/18 4/19 4/19 9:00 PM 1:00 AM 1:00 AM 4/18 9:15 PM 4/18 4/19 4/18 11:30 PM 1:00 AM 9:30 PM N Y Y Y N Y Y N N Y N Y Y Y N Y Y N N Y N Y Y N N N Y N N Y N N Y N N Y N N N N N N N N N Y Y N N N N Y N N N N Y N N Y N N N N N N Y N N Y N N N N N N N N N N N Y Y Y N N Y N N N N N N N N Y Y N N Y N N N Y N N N N Y N N Y Y Y N Y Y Y N Y Y N Y Y Y N N Y Y Y N N N N N N N N N N Y Y Y N Y Y N Y Y Y Y Y Y N Y Y N Y Y Y Y Y N N Y N N N ? Y N N Y N Y N N Y Y Y Y N Y N Y N N N N Y Y Y Y N Y Y N Y Y Y N N Y N Y N N Y N N N N N N Y N N N N N N Y N N Y Y N N N Y N N Y N Y N N N Y Y N N N N Y Y N N N Y Y Y N Y Y Y Y Y N Y N Y N Y N Y N N Y Y N Y N N N N N N N N N Y N N Y N N Y Y N N Y N Y Y Y N Y Y N N Y N Y Y Y N N Y N N Y N N Y Y N Y N N N Y N N Y N N N Y N N Y N Y N Y N Y Y N N Y N N Y Y N Y Y N N N N N N N N N N N N N N N Y N N Y Y N N Y N Y N Y N Y N N Y Y N Y Y Y Y Y Y Y Y Y Y Y Y Y Y N Y Y N Y N N Y N Y Y N Y N N N N N N N N N N Y N N Y Y Y Y Y N Y Y N N Y Y Y N Y N N Y N N N Y Y Y N N Y N N N N N Y Y Y N Y Y N N N N N N Y N N Y N N Y Y Y Y Y N N Y N N Y Y Y Y Y N Y N N N N N N N N N N Y N N Y Y Y Y Y N Y N N N Y Y N N N N N Y Y N Y N N N Y Y N Y Y Y N N Y N Y N Y N N N Y Y N Y Y Y N Y N N Y N N N N N N Line listing from investigation of outbreak of gastroenteritis, Oswego, New York, 1940 ID 41 42 43 44 45 46 47 48 49 50 AGE SEX 54 F 77 M 72 F 58 M 20 M 17 M 62 F 20 F 52 F 9 F TIME OF MEAL unk unk unk unk 10:00 PM 7:00 PM unk 7:00 PM unk unk ILL N Y Y Y N Y Y Y Y N 51 52 53 54 55 56 57 58 59 60 50 8 35 48 25 11 74 12 44 53 M M F F M F M F F F unk 11:00 AM unk unk unk unk unk 10:00 PM 7:30 PM 7:30 PM N Y N Y Y N Y Y Y Y 61 62 63 64 65 66 67 68 69 70 37 24 69 7 17 8 11 17 36 21 M F F M F F F M F F unk unk unk unk 10:00 PM unk 7:30 PM 7:30 PM unk unk N N N N Y Y N N N Y 71 72 73 74 75 60 18 14 52 45 M F F M F 7:30 PM 7:30 PM 10:00 PM unk unk Y Y N Y Y * Midnight between 4/18 and 4/19 DATE OF ONSET TIME OF ONSET 4/19 4/19 4/18 2:30 AM 2:00 AM 9:30 PM 4/18 4/19 4/19 4/18 10:30 PM 12:30 AM 1:00 AM 10:30 PM 4/18 3:00 PM 4/19 4/18 12:00 AM* 11:00 PM 4/18 4/19 4/19 4/18 10:30 PM 1:00 AM 2:30 AM 11:30 PM 4/19 4/19 1:00 AM 12:30 AM 4/19 12:30 AM 4/19 4/19 1:00 AM 12:00 AM* 4/19 4/18 2:15 AM 11:00 PM Y Y Y NNY NNY N NNNNNNNNNN Y Y NY Y NY NY N Y Y Y NNNY Y Y N NNNNNNNNNN NY Y Y N N Y N N N Y Y NNNY NNNY NNNNNNNNNN Y Y Y Y NY NNY N NNNNNNNNNN Y N NY Y Y NY Y Y YY NY NY NY Y N Y N Y ? Y Y N N Y Y N Y N Y N N N N N N Y N N Y Y N Y N Y Y Y N N Y N N Y N Y Y Y N N Y Y N Y N Y Y Y N N Y N N Y N N Y Y N N Y N N Y N N Y Y N N Y Y N Y N Y N Y N N Y Y N Y N N Y Y N N Y N N N N N N Y N N Y N N Y N N Y Y N N N Y N N N Y Y Y N N Y Y N Y Y Y Y N Y Y Y Y N Y Y N Y Y Y Y Y Y Y N Y Y Y N N N N N N N N N N N Y N Y N Y Y Y N Y N Y Y Y N N Y Y N N N Y Y Y N Y Y Y N N N N N Y N Y Y Y N Y N N Y Y N Y N N N Y N Y N Y N N Y Y N N N N Y N N N N N N N N N N N N N N N N N N Y N N N N Y Y N N N N Y Y N N Y N N N N N Y Y Y Y N Y N N N N N N Y Y N Y N Y Y N Y Y Y Y Y N Y Y N N N N N N N N N N N Y N Y Y N Y N N Y N Y N Y Y N Y N N Y N Y N Y Y N N N Y Y N N N Y Y N N N N N N N N Y Y N Y N Y N Y Y Y Y Y Y Y Y Y Y N Y N Y N N N N N Y Improved Line listing from investigation of outbreak of gastroenteritis, Oswego, New York, 1940 ** Please see bolded note at bottom of this line listing ** ID 52 31 36 40 44 24 26 20 18 6 7 46 49 57 10 22 29 55 75 38 60 12 72 54 2 3 4 17 47 66 70 71 21 27 32 33 39 9 48 58 65 8 14 43 74 42 59 16 AGE SEX 8 M 35 M 35 F 68 M 58 M 3 M 59 F 33 F 36 M 63 F 70 M 17 M 52 F 74 M 33 F 7 M 37 F 25 M 45 F 57 F 53 F 38 F 18 F 48 F 52 F 65 M 59 F 62 F 62 F 8 F 21 F 60 M 13 F 15 F 15 M 50 F 16 F 15 F 20 F 12 F 17 F 40 F 10 M 72 F 52 M 77 M 44 F 32 F TIME OF MEAL 11:00 AM unk unk unk unk unk unk unk unk 7:30 PM 7:30 PM 7:00 PM unk unk 7:00 PM unk unk unk unk unk 7:30 PM 8:00 PM 7:30 PM unk 8:00 PM 6:30 PM 6:30 PM unk unk unk unk 7:30 PM 10:00 PM 10:00 PM 10:00 PM 10:00 PM 10:00 PM 10:00 PM 7:00 PM 10:00 PM 10:00 PM 7:30 PM 7:30 PM unk unk unk 7:30 PM unk ILL Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y DATE OF TIME OF ONSET ONSET 4/18 3:00 PM 4/18 9:00 PM 4/18 9:15 PM 4/18 9:30 PM 4/18 9:30 PM 4/18 9:45 PM 4/18 9:45 PM 4/18 10:00 PM 4/18 10:15 PM 4/18 10:30 PM 4/18 10:30 PM 4/18 10:30 PM 4/18 10:30 PM 4/18 10:30 PM 4/18 11:00 PM 4/18 11:00 PM 4/18 11:00 PM 4/18 11:00 PM 4/18 11:00 PM 4/18 11:30 PM 4/18 11:30 PM 4/19 12:00 AM* 4/19 12:00 AM* 4/19 12:00 AM* 4/19 12:30 AM 4/19 12:30 AM 4/19 12:30 AM 4/19 12:30 AM 4/19 12:30 AM 4/19 12:30 AM 4/19 12:30 AM 4/19 1:00 AM 4/19 1:00 AM 4/19 1:00 AM 4/19 1:00 AM 4/19 1:00 AM 4/19 1:00 AM 4/19 1:00 AM 4/19 1:00 AM 4/19 1:00 AM 4/19 1:00 AM 4/19 2:00 AM 4/19 2:00 AM 4/19 2:00 AM 4/19 2:15 AM 4/19 2:30 AM 4/19 2:30 AM 4/19 10:30 AM * Midnight between 4/18 and 4/19 NNNNNNNNNN Y Y Y NY Y Y NY N Y Y Y Y NY Y NY N Y NY Y NNY NY N Y Y Y NNNY Y Y N NY Y NNY NNNY NY Y Y NY Y NNY Y Y Y Y Y Y NNY Y Y Y NY NY Y NNN Y Y NY Y NNNNY Y Y Y NY Y Y NY Y NY Y Y N N Y N N N Y Y Y Y NY NNY N Y Y Y Y Y Y Y NY N Y Y Y NNY Y NNY Y Y Y Y Y Y Y NNY Y Y Y NY Y Y NY N Y NY NNY Y NNY Y Y Y Y Y Y Y NY N Y Y NY Y Y Y NY N Y Y Y Y Y NY NY Y Y Y Y NNY NNY N Y Y Y Y Y NNNNY Y Y Y Y Y Y Y Y Y N Y Y Y NNY NNY N Y Y Y Y NNNNY N Y Y NNNNNNY N NNNNNNNNNN Y Y NNNY NNNY Y NY Y Y NNNNN Y NNY Y NNNNN NNNNNNNNNN NNNNNNNNNN NNNNNNNNNN NNNNNNNNNN NNNNNNNNNN NNNNNNNNNN NNNNNNNNNN NNNNNNNNNN NNNNNNNNNN NNNNNNNNNN NNNNNNNNNN NNNNNNNNNN Y Y NY Y NY NY N Y NY NY Y Y NY Y NNNNNNNNNN Y Y Y NNY NNNY Y Y NNNY NNY N NY Y Y NY NY NY Y Y Y Y Y Y NY NY NY YY NY Y Y NY Y Y Y Y Y Y Y Y Y Y Y Y NY Y Y Y Y NY NY Y Y NY NY Y Y NY Y Y Y Y Y Y Y Y NY Y N Y N NY Y Y Y Y NY NY Y Y Y Y NY Y N Y Y Y N N N ? N N Y N N N Y Y N Y Y N Y N Y Y Y Y Y N Y Y N N Y Y N N Y N N Y Y N Y Y Y Y Y Y N Y Y N Y N N Y N N N N N N N N N N N N N Y N N Y N N N N N N N N N N N N N N N N N N N N N N N Y N N Improved Line listing from investigation of outbreak of gastroenteritis, Oswego, New York, 1940 ID 1 5 11 13 15 19 23 25 28 30 34 35 37 41 45 50 51 53 56 61 62 63 64 67 68 69 73 AGE SEX 11 M 13 F 65 M 62 F 25 M 11 M 64 M 65 F 62 M 17 M 40 M 35 F 36 M 54 F 20 M 9 F 50 M 35 F 11 F 37 M 24 F 69 F 7 M 11 F 17 M 36 F 14 F TIME OF MEAL unk unk unk unk unk unk unk unk unk 10:00 PM unk unk unk unk 10:00 PM unk unk unk unk unk unk unk unk 7:30 PM 7:30 PM unk 10:00 PM ILL N N N N N N N N N N N N N N N N N N N N N N N N N N N DATE OF ONSET TIME OF ONSET N N Y Y Y Y N Y Y N Y Y Y Y N N Y N N N Y N Y Y Y N N N N Y Y Y Y N Y Y N Y Y N Y N N Y N N N Y Y Y Y Y N N N N Y N Y ? N Y N N N Y Y Y N N Y N N N Y Y Y Y Y N N N N N Y Y Y N Y Y N N N Y N N N Y N N N N N Y Y Y N N N N Y Y Y N N Y N N N N N N N N Y N N N N Y Y N N N N N N Y Y Y Y N N Y N Y Y Y Y N N Y N N N Y N Y Y Y N N N N N Y Y N N Y Y N Y Y Y N N N Y N N N N Y N N N N N N N N N Y N N N N N N N N N N N Y N N N N N N N N N N N N N N Y N N Y Y N Y Y Y Y N N Y N N N Y N N Y Y N N N N N Y Y Y N N Y N Y Y N N N N Y N N N N Y Y Y N N N N N N N Y N N Y Y Y Y N N Y Y Y Y N N N N Y Y N Y N Y N N Y N Y N Y Y N Y N N N N Y N N Y N N N N N N Y N Y Y Y N N N Y N Y Y Y Y Y Y Y Y Y Y Y Y Y N Y Y Y N Y N N N N N N N N N N N Y N N N N N N N N N N N N N N N N The 14 columns on the far right of the line listing represent the answers (Yes or No) as to whether a person ate a particular food item. The order of the columns (foods) is the same as the order of foods listed in the table on question #14. 1st: 2nd: 3rd: 4th: 5th: 6th: 7th: 8th: 9th: 10th: 11th: 12th: 13th: 14th: Baked ham Spinach Mashed potatoes Cabbage salad Jello Rolls Brown bread Milk Coffee Water Cakes Vanilla ice cream Chocolate ice cream Fruit salad PART III Please use the line listing sorted by illness status (ill or well), and by time of onset. Question 11: Where possible, using the improved line listing, calculate incubation periods and illustrate their distribution with an appropriate graph (using Excel or any other graphing software). Remember, you can only calculate incubation periods for persons who gave a “Time of Meal”. Use ½ hour increments on the x-axis. Question 12: What is the range (include minimum and maximum), the mean, the mode, and the median of the incubation periods. Question 13: Using the information on incubation period, combined with the data on clinical symptoms, conduct a differential diagnosis of the illness and name the agent you believe is responsible for this outbreak? You have enough information to answer with only one (1) agent. Explain your answer. (Please refer to the Compendium of Acute Foodborne Gastrointestinal Disease to identify the most likely agent of infection). Question 14: Using the data in the attached line listing, complete the table below. Which food is the most likely vehicle of infection? You must use the ARR or Relative Risk to determine. at Food Items Served Number of persons who ATE specified food Ill Not Ill Total Percent Ill (Attack rate) Number of persons did NOT eat specified food Ill Not Ill Total Percent Ill (Attack rate) Attack Rate Ratio or Relative Risk Baked ham Spinach Mashed potato Cabbage salad Jello Rolls Brown bread Milk Coffee Water Cakes Ice cream, vanilla Ice cream, chocolate Fruit salad ** To type a number into the cell, double-click on the cell and a cursor will appear. The ARs and ARRs need to be rounded to the hundredths (2.27 vs. 2.3). Also describe below what the RR actually means in this case by using it in a statement with the identified food.** Question 15: Based on the information you now have, explain further investigations that should be pursued, including control measures. Question 16: Why was it important to investigate a localized, small outbreak like this one? Question 17: Refer to the steps of an outbreak investigation you listed in Question 2. How does this investigation fit that outline? CENTERS FOR DISEASE CONTROL AND PREVENTION, 2003 Page 1 COMPENDIUM OF ACUTE FOODBORNE AND WATERBORNE DISEASES I. Diseases typified by vomiting after a short incubation period with little or no fever Agent Incubation period Clinical Syndrome Pathophysiology Characteristic Foods Specimens A. Staphylococcus aureus 30 min - 8 hours; usually 2-4 hours Vomiting, diarrhea preformed enterotoxin sliced/chopped ham and meats, custards, cream fillings Food: enterotoxin assay (FDA), culture for quantitation and phage typing of staph, gram stain Handlers: culture nares, skin, skin lesions, and phage type Staph. Cases: culture stool and vomitus, phage type Staph. B. Bacillus cereus 1-6 hours Vomiting; some patients with diarrhea; fever uncommon ? preformed enterotoxin cooked rice Food: culture for quantitation Cases: stool culture C. Heavy metals • Antimony • Cadmium • Copper • Iron • Tin • Zinc 5min-8 hours; usually
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