Sheet2
ID Case status Age Sex Hospitalized Dia
hea Cramps Headache Vomiting Nausea Fever Blood in stool Sore throat Dia
hea onset date Dia
hea onset time Stool sample Lab result Case definition
1 Case 34 M Y Y Y Y N N Y N N 2-May 7:00 PM Y POSITIVE CONFIRMED
2 Control 9 M
3 Case 40 F N Y Y Y N N Y N N 3-May 2:00 PM PROBABLE
4 Control 63 F
5 Case 83 M Y Y Y Y N Y Y N N 3-May 12:15 AM Y POSITIVE CONFIRMED
6 Control 35 M
7 Case 73 F N Y Y Y N Y N N N 3-May 3:00 PM PROBABLE
8 Case 34 M N Y Y N Y Y N N N 3-May 9:00 PM PROBABLE
9 Control 7 F
10 Case 34 M N N N Y N Y Y U Y POSSIBLE
11 Control 11 M
12 Control 82 M
13 Case 41 M N Y Y Y Y Y U U U 3-May 2:30 PM PROBABLE
14 Case 6 F N Y U U N Y Y U U 4-May 6:00 PM PROBABLE
15 Case 5 M Y Y U U Y Y Y N Y 3-May 2:00 AM Y POSITIVE CONFIRMED
16 Case 36 F Y Y Y Y N Y Y N N 3-May 5:00 PM Y POSITIVE CONFIRMED
17 Control 69 M
18 Case 52 F N Y Y Y N Y Y N N 3-May 4:00 PM PROBABLE
19 Case 59 M N Y Y N Y Y Y U U 3-May 1:00 PM PROBABLE
20 Control 81 F
21 Control 60 M
22 Control 57 F
23 Case 17 F N Y Y Y N Y Y N Y 4-May 6:00 AM PROBABLE
24 Case 15 F Y Y Y Y Y Y Y N Y 3-May 2:00 PM Y POSITIVE CONFIRMED
25 Control 34 F
26 Case 45 F N Y Y Y U Y Y Y N 3-May 5:30 PM PROBABLE
27 Case 49 F N Y N Y N Y Y U Y 4-May 4:00 AM PROBABLE
28 Control 35 M
29 Case 79 M Y Y Y Y Y Y Y N U 3-May 10:00 AM Y POSITIVE CONFIRMED
30 Case 81 F Y Y Y Y N Y Y Y N 3-May 5:00 PM Y POSITIVE CONFIRMED
31 Case 33 M N Y Y Y N Y Y N N 4-May 3:00 AM PROBABLE
32 Control 6 F
33 Case 31 M N Y Y Y Y U Y U U 3-May 2:00 PM PROBABLE
34 Case 29 F N Y N Y U Y Y N N 3-May 8:00 PM PROBABLE
35 Control 8 F
36 Case 55 M Y Y N Y Y Y Y Y N 3-May 4:00 PM Y POSITIVE CONFIRMED
37 Case 55 F N Y Y Y Y Y Y U Y 3-May 7:30 PM PROBABLE
38 Case 63 M Y Y Y Y N N Y N Y 3-May 1:00 PM Y POSITIVE CONFIRMED
39 Control 57 F
40 Case 48 F N Y Y Y N Y Y N N 4-May 3:00 AM PROBABLE
41 Case 24 M Y Y N Y Y Y Y Y N 3-May 7:00 AM Y POSITIVE CONFIRMED
42 Case 62 F N Y Y Y Y Y Y Y N 4-May 1:30 AM PROBABLE
43 Control 51 F
44 Case 56 F N Y Y Y N N N N N 3-May 2:00 PM PROBABLE
45 Case 58 M Y Y Y Y Y Y Y N N 3-May 5:00 PM Y POSITIVE CONFIRMED
46 Control 17 M
47 Case 49 M N Y Y Y N Y Y N N 4-May 12:01 AM PROBABLE
48 Control 17 F
49 Case 32 F N Y Y Y N Y U U N 3-May 6:30 AM PROBABLE
50 Case 37 F N Y Y Y Y Y Y N Y 3-May 7:00 AM PROBABLE
51 Case 30 M N Y Y Y N N Y Y N 3-May 11:59 PM PROBABLE
52 Control 58 M
53 Control 40 M
54 Case 23 M N Y Y Y Y Y N U N 3-May 12:30 PM PROBABLE
55 Control 53 F
56 Case 60 M Y Y Y Y Y Y Y N Y 3-May 1:00 PM Y POSITIVE CONFIRMED
57 Case 56 F N Y Y Y Y Y Y U N 3-May 8:00 PM PROBABLE
58 Control 6 M
59 Case 60 F N Y Y Y N Y U N N 3-May 11:30 PM PROBABLE
60 Control 9 F
61 Case 61 M Y Y Y Y Y Y Y N N 3-May 3:00 PM Y POSITIVE CONFIRMED
62 Case 60 F N Y Y Y Y Y Y U N 3-May 11:00 PM PROBABLE
63 Control 56 M
64 Case 69 M Y Y Y Y Y Y Y N N 3-May 11:00 AM Y POSITIVE CONFIRMED
65 Control 51 F
66 Case 29 F Y Y Y Y Y Y Y N N 3-May 5:30 PM Y POSITIVE CONFIRMED
67 Case 27 M N Y Y Y N Y Y N N 3-May 8:00 PM PROBABLE
68 Control 27 M
69 Case 39 F Y Y Y Y Y Y Y N N 3-May 6:00 PM Y POSITIVE CONFIRMED
70 Case 35 M Y Y Y Y Y Y Y Y Y 3-May 6:00 PM Y POSITIVE CONFIRMED
71 Case 15 M N Y Y Y Y Y Y N Y 3-May 9:00 PM PROBABLE
72 Control 29 F
73 Case 19 M N Y Y Y Y Y Y N N 3-May 12:00 PM PROBABLE
74 Case 18 F N N N Y Y Y Y U N POSSIBLE
75 Control 11 F
76 Case 59 M N Y Y Y N Y Y N N 3-May 2:00 PM PROBABLE
77 Case 58 F N Y Y Y N U Y N Y 3-May 3:00 PM PROBABLE
78 Case 46 F N Y Y Y Y Y U N N 3-May 10:00 PM PROBABLE
79 Control 14 M
80 Control 37 M
81 Case 47 M Y Y Y Y Y Y Y N N 3-May 12:00 PM Y POSITIVE CONFIRMED
82 Case 86 F Y Y Y Y Y Y Y N N 3-May 2:00 PM Y POSITIVE CONFIRMED
83 Control 40 F
84 Case 36 F N Y Y Y N Y Y N N 3-May 8:00 PM PROBABLE
85 Control 63 F
86 Control 42 M
87 Case 64 F N Y Y Y N Y N N N 3-May 6:00 PM PROBABLE
88 Case 64 F Y Y Y Y Y Y Y Y N 3-May 10:00 PM Y POSITIVE CONFIRMED
89 Control 49 M
90 Case 55 M N N N Y N N Y U N POSSIBLE
91 Case 44 F Y Y Y Y N Y Y N U 3-May 7:00 PM Y POSITIVE CONFIRMED
92 Case 10 M Y Y Y Y Y Y Y N N 3-May 12:30 PM Y POSITIVE CONFIRMED
93 Control 42 M
94 Control 15 F
95 Case 5 M Y Y Y Y N Y Y Y U 3-May 7:00 PM Y POSITIVE CONFIRMED
96 Case 12 F N Y Y Y N Y Y U N 3-May 8:00 PM PROBABLE
97 Control 11 F
98 Case 45 M N Y Y N Y Y N N Y 3-May 1:00 PM PROBABLE
99 Case 46 F N Y Y Y N Y Y U N 3-May 5:00 PM PROBABLE
100 Control 5 M
101 Control 81 F
Exercise # 1 - Measures of Risk
Infectious Disease Epidemiology
OUTBREAK INVESTIGATION
Scenario:
For this workshop on out
eak investigation you are an epidemiologist working for the Foodborne and Dia
heal Diseases Branch, the
anch of CDC that investigates out
eaks that occur on cruise ships. Your
anch chief informs you that there has been an out
eak of dia
hea with high fever on a ship that has recently returned from the Bahamas. Using the actual data collected during this real out
eak of food-borne illness aboard a cruise ship, you will investigate the out
eak and make recommendations for controlling this out
eak and preventing similar out
eaks in the future.
Background Information:
The cruise ship "Fantasy" came into Cape Canaveral, FL, early in the morning on May 4, 1995, several hours ahead of schedule, because of an out
eak of fe
ile dia
hea on board. The symptoms—a rapid onset of fever, vomiting, and dia
hea, in some cases bloody—were typical of Shigella sonnei infection. Shigella can be transmitted in contaminated food or water or by direct fecal-oral transmission. Paramedical personnel had been summoned, and patients, many with IVs already in place as they were taken off the ship, had been taken to the emergency departments of 5 local hospitals. The cruise ship captain notified the Vessel Sanitation Program, a CDC program for cruise ships, of the out
eak, and a standard questionnaire was distributed to passengers who had not yet disembarked. There are so many cruise ship out
eaks that a standard questionnaire has been developed. It asks about illness onset, symptoms, food consumption, and use of the ship's water and ice. If the ship's water system is implicated, then different measures need to be taken than for a standard food-borne out
eak, and the ship may not be able to set out to sea again. In this case, the ship’s water and ice were not associated with illness.
The “Fantasy” had departed from Cape Canaveral on April 30 for a 4-day cruise to the Bahamas, docking in Freeport on May 1 and in Nassau on May 2, and spending May 3 at sea. On May 2, 393 passengers went on an optional tour to Blue Lagoon Island, which included a lunch on the beach provided by an on-shore caterer. The captain reported that all of the sick passengers had gone on the Blue Lagoon tour. The incubation period of Shigella infection is 12-96 hours. The initial questionnaire was returned by only 8 ill passengers, although 64 patients had already been sent to the hospital. The 8 newly identified ill passengers were
ought to the hospital for evaluation.
For more on:
Shigellosis: https:
www.cdc.gov/shigella/index.html
Cruise ship travel recommendations: https:
wwwnc.cdc.gov/travel/page/cruise-ship
CDC’s Vessel Sanitation Program: http:
www.cdc.gov/nceh/vsp/default.htm
As soon as you a
ive at work on May 4, your
anch chief asks you to go to Florida and investigate. Before heading to the airport, you assemble laboratory supplies. You also reach several passengers in Cape Canaveral hospitals by telephone and try, from their accounts of the buffet, to make a list of the food items that had been offered for lunch on the Blue Lagoon tour. On the airplane, you develop a simple questionnaire including illness information and food exposures based on the menu items served at the Blue Lagoon lunch. You strongly suspect a foodborne out
eak, so you plan to do a study to determine which, if any, of these menu items were associated with illness. You a
ive in Cape Canaveral later that day with two assistant investigators.
You and your team visit the 5 local hospitals to administer the questionnaire to ill cruise ship passengers. Of the 72 passengers sent to Cape Canaveral hospitals for evaluation of the fe
ile dia
heal disease, 23 were admitted for medical treatment. Following standard procedure, hospital staff attempted to collect stool samples from the 23 hospitalized patients to test for Shigella infection and other common infectious agents that cause fe
ile dia
heal disease. You are able to track down 63 patients and 62 agree to complete your questionnaire (including all 23 of the hospitalized patients). You were unable to collect stool samples from patients who were not hospitalized.
You know that you will also need to interview some non-ill passengers to compare to these ill passengers. Some members of your group back at CDC feel that you should sample the controls randomly from a list of all the passengers who went on the Blue Lagoon tour, but others feel that this would be impractical, since the passengers have all disembarked and most have returned home. As it turns out, the cruise ship does not have a list of Blue Lagoon passengers available. Instead, you decide to interview well friends and family members who accompanied the patients to the hospital. Although you know that this has some limitations for sampling controls, you decide that under the circumstances, this is the best that you can do.
Data Collection: Your team interviews all of the passengers that you can find. Each person is interviewed using the questionnaire that you developed earlier that day, on which the investigator records whether the person was sick, what their symptoms were, and whether they ate each of the foods served at the Blue Lagoon tour.
Table 3. Onset of Dia
hea Among 59 Ill Passengers Reporting Dia
hea – Date and Time
Date
Time
Date
Time
2-May
7:00 PM
3-May
6:00 PM
3-May
12:15 AM
3-May
6:00 PM
3-May
2:00 AM
3-May
6:00 PM
3-May
6:30 AM
3-May
7:00 PM
3-May
7:00 AM
3-May
7:00 PM
3-May
7:00 AM
3-May
7:30 PM
3-May
10:00 AM
3-May
8:00 PM
3-May
11:00 AM
3-May
8:00 PM
3-May
12:00 PM
3-May
8:00 PM
3-May
12:00 PM
3-May
8:00 PM
3-May
12:30 PM
3-May
8:00 PM
3-May
12:30 PM
3-May
9:00 PM
3-May
1:00 PM
3-May
9:00 PM
3-May
1:00 PM
3-May
10:00 PM
3-May
1:00 PM
3-May
10:00 PM
3-May
1:00 PM
3-May
11:00 PM
3-May
2:00 PM
3-May
11:30 PM
3-May
2:00 PM
3-May
11:59 PM
3-May
2:00 PM
4-May
12:01 AM
3-May
2:00 PM
4-May
1:30 AM
3-May
2:00 PM
4-May
3:00 AM
3-May
2:00 PM
4-May
3:00 AM
3-May
2:30 PM
4-May
4:00 AM
3-May
3:00 PM
4-May
6:00 AM
3-May
3:00 PM
4-May
6:00 PM
3-May
3:00 PM
3-May
4:00 PM
3-May
4:00 PM
3-May
5:00 PM
3-May
5:00 PM
3-May
5:00 PM
3-May
5:00 PM
3-May
5:30 PM
3-May
5:30 PM
1. Construct an epidemic curve for onset of dia
hea (a histogram with time of onset on the x-axis and number of cases on the y-axis). Use whatever unit of time makes most sense for the data. The incubation period for Shigella infection is usually about 12-96 hours, although it can be longer. you should create a publication-worthy figure using Excel
2. Based on your epidemic curve, do you think this was a point source or a propagated out
eak? When (day/time) do you think the exposure occu
ed? Think both about the incubation period of Shigella infection and the specific details of the timing of this out
eak.
Part 2
Based on the additional Excel document provided labeled Fantasy Ship answer the following questions.
1. Considering person, place, and time, how would you characterize this out
eak by person (i.e., demographics)?
2. Describe the cases by person. Combine confirmed and probable cases.
Using data from the food questionnaires, you construct Table 3, which presents the data on reported food exposures among ill and well persons. Calculate the appropriate measure of association and 95% confidence interval* between each food item and illness. Exclude those with missing data from your calculation.
Table 4. Exposure Assessment for Ill and Well Passengers – Results of Food Questionnaires
Food Exposure
Sick
Not sick
Total
Measure of Association (95% CI)
Ate Ribs?
Yes
No
Don’t Know
51
10
1
32
7
0
83
17
1
Ate Pasta Salad?
Yes
No
Don’t Know
54
6
2
4
34
1
58
40
3
8
3. Consider the 95% confidence intervals for the measures of association in the above tables. Are the confidence intervals na
ow or wide? Why? Does knowing the confidence intervals affect your conclusions about the source of the out
eak?
4. You conclude that the pasta salad is the likely source of the out
eak. How would you further investigate the source of the out
eak?
5. What control measures would you implement immediately?
6. After completing this phase of the investigation, what recommendations would you make for next steps? Consider both any further investigations that you might think are necessary for this out
eak and any follow-up and recommendations that you would make to prevent future similar out
eaks.
Risk (or Prevalence) Ratios and Differences
Exposed
Unexposed
Cases
a
c
Non-cases
d
Total People at Risk
N1
N0
Odds Ratios
Exposed
Unexposed
Cases
a
c
Controls
d
Incidence Rate Ratios and Differences
Exposed
Unexposed
Cases
a
c
Non-cases
d
Total Person-time at risk
PT1
PT0
Exercise # 1 - Measures of Risk
Infectious Disease Epidemiology
OUTBREAK INVESTIGATION
Scenario:
For this workshop on out
eak investigation you are an epidemiologist working for the Foodborne and Dia
heal Diseases Branch, the
anch of CDC that investigates out
eaks that occur on cruise ships. Your
anch chief informs you that there has been an out
eak of dia
hea with high fever on a ship that has recently returned from the Bahamas. Using the actual data collected during this real out
eak of food-borne illness aboard a cruise ship, you will investigate the out
eak and make recommendations for controlling this out
eak and preventing similar out
eaks in the future.
Background Information:
The cruise ship "Fantasy" came into Cape Canaveral, FL, early in the morning on May 4, 1995, several hours ahead of schedule, because of an out
eak of fe
ile dia
hea on board. The symptoms—a rapid onset of fever