investigation of foodborne outbreak on a cruise ship
CASE STUDY 2 INSTRUCTIONS
You will assume the role of the investigator for the following foodborne illness case file. You will analyze the data, determine attack rates, and perform the statistical calculations necessary to find and association with disease and determine a likely source of the outbreak. (Hint: graphs and tables included in this case file may be useful). You will then develop a plan to stop the propagation of the outbreak and create an educational program for food handlers to highlight prevention of a similar outbreak in the future. You should ensure that all practices and recommendations are in accordance with the regulations of the governing agency. You should include a reference page with a minimum of 5 sources from government publications. The paper should be 8 pages, double-spaced, and include formatting consistent with either the APA or AMA style guide. Case Study 2 is due by 11:59 p.m. (ET) on Sunday of Module/Week 7.
Case: You have just finished your MPH at Liberty University and have taken a position with the CDC in the Vessel Sanitation Program (VSP). Today, you have been asked to participate in an investigation of the outbreak of a diarrheal illness aboard the cruise ship Warped Imagination bound to Miami from a Caribbean voyage.
In accordance with VSP protocol, the chief medical officer on board the ship has kept a log of illness among the crew and passengers. Sick passengers and crew were instructed to begin a BRAT diet (bananas, rice, apple sauce, tea, and toast). Normally a formal count would be presented to the VSP 36 hours prior to arrival in the US; however, on the fifth day of the trip a total of 67 cases of diarrheal illness had been recorded among the 2500 passengers and 3 cases of a similar illness among the 1200 crew. Afflicted crew members and all food handlers have been removed from duty. It is now the 6th day of the trip and, since the case load has reached the 2% threshold for passengers, the medical staff has filed the mandatory report of the situation to the VSP.
The ship has made ports of call at Key West; Ocho Rios, Jamaica; Cozumel, Mexico; Belize; and Grand Cayman. The remaining ports of call have been canceled and the ship is en route to Miami as the capacity of the medical staff to provide care may soon be exceeded by the case load of victims requiring IV therapy. The captain expects to make it to Miami within about 48 hours provided the weather cooperates.
The first case of the illness was logged on the second day of the cruise about 4 hours after departing from Ocho Rios. The index case is a 26 year-old newlywed white female from Philadelphia. Her husband has not experienced any symptoms. The wedding was the day prior to their departure from Philadelphia. Their only meal the day of the wedding was a catered dinner of chicken and beef barbeque, mashed potatoes, mixed steamed vegetables, a tossed salad, wedding cake, fruit punch and a glass of champagne. The caterer also provided a box of leftovers which the couple snacked on that evening and again just prior to leaving for the airport on the day the cruise began. They consumed only the complimentary Coke and pretzel snacks during their flight between the time they left home and the time when they had boarded the ship went to the buffet as soon as they could. The couple disembarked at Key West, the first port of call, where they ate Key Lime Pie and coffee. The couple had no water, alcoholic beverages or other food while ashore. That evening they were among the first passengers to eat from the buffet on the ship (See Table 1 for her food diary). The woman was feeling a bit of malaise and wanted to retire early. The following day, the couple had a light breakfast of fruit, yogurt, toast and coffee aboard ship just before making the port of call in Jamaica. The woman claims to have had no appetite that morning and while ashore only sipped a bottle of water acquired from the ship. She consumed no food in Ocho Rios. Her husband had a cola and salt fish.
TABLE 1 onboard food consumption by index case
foods eaten day 1 day 2 day 3 day 4 day 5
coffee yes yes no no no
hot tea no no yes yes yes
iced tea no no yes yes yes
fountain drink no no yes yes yes
ice yes yes yes yes yes
watermelon yes yes no no no
pineapple yes yes no no no
cantaloupe yes yes no no no
grapefruit yes yes no no no
passion fruit yes yes no no no
kiwi yes yes no no no
papaya yes yes no no no
banana no yes yes yes yes
apple juice yes yes no no no
prime rib yes no no no no
Hawaiian ham yes no no no no
green beans yes no no no no
carrots yes no no no no
creamed corn yes yes no no no
broccoli yes no no no no
tossed salad yes no no no no
white rice no yes yes yes yes
boiled potato yes no no no no
cole slaw yes no no no no
tomato slices yes yes no no no
yogurt no yes no no no
white bread yes no no no no
apple sauce no yes yes yes no
ice cream yes no no no no
apple pie yes no no no no
cheese cake yes no no no no
Ten additional cases were diagnosed by the medical staff the fourth day of the voyage and a total of 70 cases was either diagnosed or self-reported by the fifth day (Table 2). The predominant symptoms reported are vomiting and diarrhea. A low grade fever is variable. Everyone afflicted, including the index case, continued to have intermittent diarrhea and loss of appetite when the initial report was made to VSP.
Table 2 onset of cases aboard cruise ship
day 1 day 2 day 3 day 4 day 5
new passenger cases 0 1 0 7 59
new crew cases 0 0 0 3 0
total new cases 0 1 0 10 59
total cumulative cases 0 1 1 11 70
non ill 3700 3699 3699 3689 3630
Detailed food diaries during port of calls for each victim are not available; however, only passengers and crew who have consumed food from the ship’s buffet have become ill. Table 3 is a working spreadsheet of foods consumed by the passengers and crew from the buffet while on board the ship comparing afflicted and non-afflicted individuals.
TABLE 3: Food Consumption from Buffet Aboard Warped Imagination
afflicted passengers and crew non-afflicted passengers and crew
foods eaten day 1 day 2 day 3 day 4 day 5 day 1 day 2 day 3 day 4 day 5
bacon 43*** 37*** 34*** 10 0 3000 2763 2879 2556 2865
sausage 24 12 0 12 0 1287 1534 1302 698 779
fried ham 12 17 12 7 0 615 863 827 793 654
pancakes 28 63 27 24 0 1377 3312 1743 1752 1297
French toast 34 12 26 18 0 2300 1389 1476 1576 1681
scrambled eggs 47*** 43*** 39*** 37 0 2548 2334 2089 2192 2212
cold cereal 15 15 12 10 0 800 778 731 803 768
skim milk 66 66 66 57 0 3478 3478 3478 3478 3478
whole milk 3 3 3 0 0 175 175 175 175 175
coffee 70*** 70*** 69*** 59** 0 3497 3512 3612 3597 3581
hot tea 40 40 41 47*** 70*** 2069 2109 2211 2075 2075
iced tea 40 40 41 47 70*** 2081 1056 2112 2333 2100
fountain drink 49*** 53*** 54*** 63*** 61*** 2217 2749 2757 2566 2239
ice 70*** 70*** 70*** 70*** 70*** 3630 3618 3624 3630 3630
oatmeal 1 2 1 1 0 122 103 99 76 61
watermelon 60*** 60*** 60*** 50 0 968 763 428 534 677
pineapple 45* 45 40 30 0 2413 2425 2451 2312 2433
cantaloupe 47*** 47*** 45*** 35 0 1287 1286 1290 1301 1287
grapefruit 12 15* 15 11 0 778 779 783 775 715
passion fruit 30 35 45 43 0 1563 1823 2345 2330 2312
kiwi 30 35 35 35 0 1547 1837 1832 1815 1821
papaya 46 47 44 39 0 2401 2412 2397 2076 2073
banana 50*** 53*** 59*** 49*** 70*** 2593 2852 3112 3018 2987
apple juice 55 54 49 47* 65** 2853 2853 2597 2540 2543
grapefruit juice 0 0 0 0 0 1238 1227 1199 1328 1213
hamburger 70*** 70*** 70*** 59 0 2567 2312 2214 2237 2412
fried chicken 23 14 12 30 0 1296 769 756 1612 987
prime rib 70*** 69 58 43 0 3630 3627 3200 2300 2413
Hawaiian ham 59 53 36 38 0 3085 2714 1869 2078 2217
green beans 68** 60 60 53 0 3530 3121 3108 3123 3119
carrots 63 60 38 41 0 3269 3114 1999 2133 2210
creamed corn 35 38*** 34 31 0 1036 667 623 519 543
broccoli 33 45 27 28 0 1813 2334 1554 1563 1567
tossed salad 41 63 40 32 0 2232 3278 3206 2111 2328
white rice 53*** 48*** 43*** 70*** 70*** 2750 2599 2319 2526 2417
mashed potatoes 69*** 67* 65 54 0 3602 3526 3418 3515 3591
boiled potatoes 52* 50 54 36 0 2704 2594 2852 2598 2419
potato salad 43 37* 40 13 0 2333 2071 2075 2140 2167
cole slaw 34 33 33 12 0 1728 1823 1873 1856 1917
tomato slices 70*** 70*** 69** 59 0 3387 1292 1721 1312 1097
asparagus 33 12 25 0 0 1847 1783 1299 1717 787
yogurt 40 12 18 0 0 2047 1555 1113 1719 1982
leaf lettuce 15 33 39 26 0 863 1888 2077 1350 1613
cheddar cheese 25 25 27 23 0 3312 1543 1397 1192 2109
white bread 35 35 35 35 70*** 1763 1918 2019 1815 1772
apple sauce 13 17 14 11*** 70*** 694 893 771 663 894
ice cream 20 23 24 21 0 1067 1284 1281 1093 1123
apple pie 56* 53* 49* 48 0 2988 2748 2587 2554 2548
chocolate cake 66** 67* 56* 43 0 3423 3478 3005 3397 3414
cheese cake 61 60* 58* 48 0 3400 3200 3010 3111 3093
* indicates food consumed by a sickened crewmember
CASE STUDY 2 GRADING RUBRIC
Criterion
Points Possible Points Earned Comments from Instructor
Comprehensive analysis of the data 20
Statistical calculations demonstrate an association with disease and determine a likely source of outbreak 30
Identification of probable source(s) 20
Actions taken to stop outbreak 40
Educational program for food handlers that highlights prevention of similar outbreak from reoccurring 40
Minimum of 5 appropriate references at 6 pts. each 30
Formatting of the paper and reference page should be consistent with either the APA or AMA style guide 20
Total Points 200