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Approximately 300 persons attended a retirement party at the Nebraska State Capitol held on May 27, 1999. Most of the attendees worked in the Capitol. A private caterer (Caterer A) prepared and served food for the reception. Based on initial telephone interviews of persons reporting illness, the predominant symptoms were nausea and diarrhea, and the incubation period was approximately 24-30 hours.
The following foods were served at the retirement reception: Swedish meatballs, taco dip, crab dip, a vegetable tray and herbed ranch dip, cake, nuts and mints. The vegetable tray consisted of cucumbers, broccoli, cauliflower, carrots, celery, green peppers, and radishes. All foods were prepared onsite on the day of the reception with the exception of the nuts, which were purchased by a coworker, and the mints, which were made by a coworker.
The Swedish meatballs consisted of ground beef, ground pork, sour cream and flour. The meatballs were cooked twice. The taco dip contained layers of cream cheese mixed with salsa, ground beef, tomatoes, lettuce, onion, cheese and salsa. The taco dip was prepared manually by Caterer A in the kitchen at the State Capitol, and was not cooked after assembly. The crab dip contained canned real crab, cream cheese and ketchup.
The investigators received completed surveys from 227 attendees. Of those 227 attendees, 128 (56%) persons reported a gastrointestinal illness within 72 hours of the reception. The average interval between time of food consumption and onset of illness was 32.3 hours (range 6 to 67 hours). Table 1 shows the symptoms reported by ill attendees. The duration of symptoms generally lasted 24 to 36 hours. One person reported being symptomatic for five days. Eight persons sought medical treatment, mostly for re-hydration therapy.
Persons working in the security office at the State Capitol ate samples of the items served at the reception except the taco dip. None of the people from this office reported illness. Table 2 shows the association of illness and eating the taco dip.
Table 1: Distribution of Symptoms Reported in Persons Meeting the Case-definition.
Symptom |
Number (%) |
---|---|
Nausea |
117 (92.9%) |
Diarrhea |
111 (88.1%) |
Abdominal Cramps |
92 (74.2%) |
Vomiting |
90 (72.0%) |
Headache |
87 (70.7%) |
Chills |
73 (59.8%) |
Muscle aches |
72 (59.5%) |
Sweats |
67 (55.4%) |
Bloody diarrhea |
0 (0%) |
Table 2: Association of Illness and Exposure to Taco Dip
Ate Taco Dip? |
Met Case-definition |
Did not meet Case-definition |
Total |
---|---|---|---|
Yes |
112 |
8 |
120 |
No |
15 |
77 |
92 |
Total |
127 |
85 |
212 |
Which of the following agents most likely caused this outbreak. Briefly describe your answer. (5 points)
Disease or Causative Agent |
Incubation period |
Symptoms |
---|---|---|
Staphylococcal Food Poisoning Staphylococcus aureus |
2-4 hours (0 - 7) |
Abrupt onset of severe nausea, cramps, vomiting, malaise |
Salmonellosis Salmonella spp. |
12-36 hours (6 - 72) |
Sudden onset of abdominal pain, fever, nausea, diarrhea; sometimes vomiting |
Clostridium perfringens Food Poisoning |
10-12 hours (6 - 24) |
Abdominal cramps and watery diarrhea; sometimes with nausea, vomiting and fever |
Escherichia coli 0157:H7 Food Poisoning |
4 days (3 - 9 days) |
Abdominal cramps, watery diarrhea which later becomes grossly bloody; sometimes vomiting |
Norwalk Virus and Norwalk-like Viruses |
16-48 hours (5 - 72) |
Nausea, abdominal cramps, vomiting, watery diarrhea |
Common Food |
Contributing Factors* |
Duration and Annual US Cases |
---|---|---|
Poultry and meat products, egg and potato salads, sauces, dairy products, cream filled baked products |
1, 3, 5 |
Usually Less than 24 hours 1,200,000 cases |
Poultry and meat products, eggs, milk, melons, chocolate |
1, 2, 3, 5 |
Several days 3,000,000 cases |
Meats, poultry, soups, gravies, sauces, stews, casseroles |
1,2 |
Usually less than 24 hours 650,000 cases |
Ground beef, raw milk, any foods handled by infected person |
2, 5 |
2 - 9 days number of cases undetermined |
Shellfish, any foods handled by infected person |
1, 4, 5 |
24 - 48 hours 181,000 cases |
*Most common, as established by CDC:
1) Improper holding temperatures;
2) Inadequate cooking;
3) Contaminated equipment;
4) Food from unsafe source;
5) Poor personal hygiene
6) Other
A. graphically
displays the scope of an outbreak
B. shows the number of people affected by an outbreak
C. shows the course of the outbreak over time
D. all the above
E. A and B
Please match the following words with the most correct definition.
Mean
Endemic
Epidemic
Median
Incidence
Mode
Prevalence
Pandemic
Please match the disease with the outbreak.
A. Cholera
B. HIV/AIDS
C. Salmonella
D. Influenza
E. Plague
F. Smallpox
G. Malaria
1. __ The Black Death, Europe, Middle Ages
2. __ Worldwide respiratory illness epidemic, 1918-19
3. __ Waterborne outbreak, London 1854
4. __ Rare Cancer-cluster identified, LA 1980-81
5. __ Schwan's ice cream, US, 1994
The rates described in the articles are what type of rates?
A. Incidence rates
B. Point prevalence rates
C. Morbidity rates
D. Mortality rates
E. Attack rates