It is a Tuesday evening at 4:59pm and you are leaving the local health department where you serve as the lead epidemiologist. The phone rings, when you answer, it is the Health Services director at a local, residential college. The students arrived on Campus on Saturday, by today, several dozen students have reported to the college health clinic with nausea, vomiting, stomach cramps and diarrhea. The first student reported to the clinic at 8:15am, by 4:30, the clinic had seen 3 dozen cases. There are 3001 students at the college.

Question 1: Which of the following agents would you suspect? Provide the incubation period for each.

Question 2: What is the current attack rate of the disease? (show your work)

UPDATE: Wednesday, August 22nd 5pm

Since this afternoon, 75 additional students have reported ill to the clinic, an additional seven went to the local hospital due to advanced symptoms. In addition, you have learned that at least one parent, who was dropping their child off at the college, has reported to their local hospital with similar symptoms.

You call the local hospital to get information regarding the seven students who went there and learn that all seven were admitted and are being treated with fluids. The hospital tells you it has collected stool samples and sent them to the lab for analysis.

Question 3: Which of the following should you do next? (include an answer for each option)

Question 4: What information do we need about the people who are ill?

Question 5: Provide a case definition

Question 6: Provide an updated attack rate (show your work)

UPDATE, Thursday, August 23rd, 10am

The hospital laboratory tested samples came back positive for Staphylococcus aureus.

Question 7: Provide epidemiological overview of Staph, aureus.

Question 8: Create an epi curve based on what you know at this point.

If you need additional assistance with how to create an epi curve, use this resource: https://www.cdc.gov/training/quicklearns/createepi/

Draw epi curve on graph paper below. 

Question 9: Does the shape of the epi curve indicate a point source outbreak or a propagated outbreak?

Question 10: Now that you know the agent involved (Staph), how will you identify the specific source of the outbreak?

Question 11: Provide an updated case definition based on what you now know.

UPDATE, Thursday, August 23rd, 1pm

You receive a complete list of the names, addresses, phone numbers and email addresses for all 3,001 students at the college. After reviewing the data further, you notice that 58 of those that are sick, are freshmen. There are 307 incoming Freshmen.

Question 12: Other than the students, who else should you test/interview for possible exposure?

Question 13: Define case-control study (provide your source)

Question 14: Define cohort study (provide your source)

Question 15: would a case-control or cohort study be more appropriate for this outbreak? Explain your rationale.

Question 16: calculate the risk ratio for freshmen. (show your work)

UPDATE, Thursday, August 23rd, 3pm

You have learned that there was a special “Back to School” event for Freshmen and their families. The event was held outside, and included a buffet, people passing by could have eaten it, but it was specifically for Freshmen and their families. You have decided to send a survey to all those who are at risk.

Question 17: What is the best method for communicating with all those at risk?

Question 18: What population would you start with? (i.e. who is your highest risk group?)

Question 19: Draft an email and questionnaire to send to those at risk for the outbreak.

(You will have TWO work products for this question: 1-email to your target population and 2-a questionnaire/survey

EMAIL: (type your email below, do NOT attach it in a separate document)

SURVEY: (type your survey questions below, do NOT attach them as a separate document)

UPDATE, Friday, August 24th 11am

You and your team compare survey results of those who became ill and those who did not. Meanwhile, the lab sends confirmation from sample testing the buffet, that the pasta salad tested positive for Staph aureus.

Question 20: what recommendations (control measures) would you make to the kitchen staff to reduce the chances of another outbreak? Provide sources to support your answer.