Fictious Epidemiology Investigation
Introduction to Epidemiology
Individual Project: Outbreak Investigation in Poughkeepsie, NY
Due Date: April 22, 2021 by 5:00pm
Section A: An Outbreak of Illness (25% of final grade, 50 points max)
The New York Department of Health is notified by a physician attending at the Golden Age Retirement home in Poughkeepsie, NY that on the morning of November 14, 2019, nineteen nursing home residents reported an unusual occurrence of illness. Common symptoms, in decreasing order of frequency, included headache, diarrhea, eye and throat irritation, blurred vision, rapid or irregular heartbeat, and confusion. On physical examination most of the residents demonstrated normal blood pressure, hyperactive bowel sounds, and mild redness of the conjunctivae. The median duration of symptoms was 18 hours with an incubation period of 1 to 36 hours. The only symptom that lasted longer than 12 hours was headache. No other physical signs or symptoms were identified.
- Is this a common source outbreak (with disease transmission from a single source)? What information has been presented to support or refute this? (3pts)
- What are some of the possible causes of the illness (in terms of agent and transmission)? (3pts)
- What other information do you need to determine the extent of the problem? (2pts)
Initial investigation by ED physicians and the New York Department of Health yielded the following additional information:
- The nursing home had a total of 76 residents and 30 employees. In addition to the 19 residents who were evaluated in the ED, 6 staff members were absent and 8 additional residents reported ill on November 14. A survey of nursing home residents and employees was conducted by the county epidemiologist and revealed the majority of these groups had symptoms compatible with upper respiratory infections, including fever, cough, malaise and runny nose. Six of the 8 ill residents and three of the six ill staff members reported symptoms similar to those who presented to the ED. None of the other residents or staff reported similar symptoms.
- The nursing home has a cafeteria where most residents and staff eat their meals. In the 24 hours preceding the onset of illness, 9 of the 19 residents with these symptoms ate in the cafeteria.
- The nursing home is served by the town water system and the town sewer system.
- Surveillance of the community outside the nursing home revealed no additional cases.
- Appendix A (pg.7) provides demographic and clinical information on each of the 19 cases. Of the 76 nursing home residents, 32 were male and 44 were female. The mean age of all female nursing residents was approximately 72 years, and the mean age was approximately 69 years for all male nursing residents. The mean age for the total nursing home resident population was 71 years.
- No further cases were reported after November 14th, 12 noon.
- From the information that you now have, what people are most likely to be affected? Summarize your evidence. (4pts)
- From all this information, how would you define a case? What are the advantages and disadvantages of your definition? (4pts)
- What would you conclude from the findings presented in Appendix A? (2pts)
- What percentage of cases had blurred vision? Diarrhea? Headache? (3pts)
- Create a way to show the distribution of cases in time. (4pts)
- What does this display tell you? (4pts)
Section B: Environmental Investigation
As part of the investigation, the New York Department of Health requested technical assistance from the Centers for Disease Control and Prevention’s Division of Environmental Health. CDC epidemiologists deployed to the Golden Age nursing home in Poughkeepsie, NY. The Golden Age nursing home presented a floor plan of its facility. Plot the residents’ locations on the diagram of the nursing home shown in Appendix B (pg.8).
- Describe the distribution. (2pts)
- Now, what are your hypotheses about possible sources and transmission of the agent? (4pts)
- What are the next steps you would take? (3pts)
The investigation further reveals that in 2004 a new centralized air conditioning and ventilating system was installed to serve the library, media room, yoga studio, computer room, art classroom, sunroom, and sewing room of The Golden Rule Nursing home. Areas served by this central air system are shown in Appendix C (cross-hatched areas). At the time of the outbreak 43 nursing home residents (23 males, 20 females) were in areas served by this central unit. All other 33 nursing home residents were in other areas of The Golden Rule Nursing home.
- Calculate the attack rates of those who were located inside and outside those areas served by this central air conditioning and ventilating system. (2pts)
- Has this changed your hypothesis about the etiology of this outbreak and transmission? What is the most likely hypothesis now? (2pts)
- In the areas served by this system, are the attack rates for males and females different? How do these attack rates differ from students located of outside areas served by this system? How do you explain the difference? (3pts)
- What are important criteria in determining whether a causal relationship exists between an exposure and an outcome? Which of these criteria were met in this outbreak investigation? (5pts)
Appendix A: Information on the 19 nursing home resident cases
|Case#||Sex||Age||Location||Onset (11/14/19)||Blurred vision||Diarrhea||Headache||Eye Irritation||(Hours)||Visited ED|
DR= Don’t remember
L=Library MR=Media room
YS=Yoga studio CR= Computer room
AC=Art classroom SR=Sunroom
Appendix C: Floor Plan of Golden Rule Nursing Home (Case Locations)