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Investigative Cases
The Case: Outbreaks

(10/16/00): Local health officials contacted the CDC (Centers for Disease Control) in Atlanta due to a recent outbreak of diarrheal illness at the Sunnypark Adult Care Center. This was the third such occurrence in the area during the past two weeks. Twenty-two of thirty people developed diarrhea, fever, headache, nausea, and vomiting. Three of them were transported to Mercy Hospital and are still listed as critical. John Peterson of the State Health Department commented that, The public should be assured that we are aggressively pursuing the cause of these three outbreaks.

(10/18/00): Mercy Hospital officials and CDC representatives held a press conference to announce that two of three individuals stricken with a diarrheal illness passed away last night. Mercy Hospitalís representative, Dr. Jasmine Richards, reported that the final patient is stable and they hope for a full recovery. Dr. Wayne Wilson of the CDC announced that a full report will be released within the week. The CDCís detailed report will include the potential cause(s) of the three outbreaks, the mechanism of the illness, and the best recommendation to decrease any further occurrences.

Case Author:
Mark Salata Gordon College

Case Analysis

What are likely concerns, issues, or problems raised by case investigators?

  • The definition and causes of outbreaks
  • How to design a plan to eliminate or reduce the chance of future outbreaks
  • Public policies and regulations related to disease control
  • Medical treatments for disease
  • Basic science behind medical treatments for disease

Option: Include a know / need to know chart like the one below:

What do you know?
What do you need to know?

Learning Goals


  • what an outbreak is and the underlying circumstances leading to an outbreak.
  • overuse of antibiotics
  • improper food preparation
  • natural selection for resistant bacterial strains
  • host/pathogen interactions
  • public policy for infectious disease control



Investigations and Activities

  • Natural selection exercise (team of two)

    • Mixture of beans and styrofoam bowl, holes Hypothesis, Prediction

    • Table data

    • Graph data

    • Discussion/Conclusions

    1. Investigative Activities
      Antibiotic resistance exercise using transformed bacteria and selection scheme (team of two)

      • plasmid with AmpR gene and KanR gene (one mutation in the KanR gene)

      • grow in no, single, and double selection media

      • cycle through several generations (inoculate, shake O/N, plate and freeze aliquots Ė repeat next week)

    2. Model for bacterial growth with antibiotic treatments (team of two)

      • This will be developed if not already available (did not find anything yet)

      • Program allows for multiple antibiotic treatments in various geographical areas.

      • The incidence of bacterial growth and resistance is displayed graphically.

      • Maybe in the new EDM packet?

    3. Case-Based Investigation

      • In teams of 4 the students will use the scenario and resources to discover:

    - the cause of the outbreaks

    - the underlying mechanisms

    - produce the best plan to decrease the chance of future outbreaks



    Background Material

    The Rise of Antibiotic-Resistant Infections (Ricki Lewis)

    Insights from Evolutionary Biology (Paul W. Ewald)


    CDC: Emerging Infectious Disease

    Introduction to Antimicrobial Drugs

    Bacteria information

    CDC: Increasing prevalence in the United States of multidrug-resistant Streptococcus pneumoniae.

    CDC: erythromycin resistance

    TB: Ancient Killer on the rebound

    Free Press Articles

    Students will usually obtain additional references or resources
    to help answer or explore their questions.

    Special Data Items

    Patient 1
    Male, Age 68, adult care center client
    nausea, fever, diarrhea as of 10/15/00
    Treatment: rehydration, antibiotic cocktail

    Patient 2
    Female, Age 79, adult care center client
    fever, diarrhea as of 10/14/00
    Treatment: rehydration, antibiotic cocktail

    Patient 3
    Male, Age 38, adult care center employee
    nausea, fever, diarrhea as of 10/13/00
    Treatment: rehydration, antibiotic cocktail
    Released as of 10/18/00

    CDC investigative teamís notes

    Outbreak #1

    Preschool 10/09/00-10/11/00
    12/18 children with fever and diarrhea
    10 recovered with hospitalization, 2 died
    Show and Tell day a few days earlier Ė pets
    Milk and cookies break as well as lunch in common.
    Water fountain and kitchen recently passed inspection.

    Outbreak #2

    Residential homes 10/07/00-10/10/00
    5 children and 4 adults n
    All children younger than 9 yrs. of age and all adults n
    older than 50 yrs. except for one (he was 24 yrs. old).
    All recovered except for the 24 yr. old. He was diagnosed n
    at the age of 19 with HIV.

    Outbreak #3

    Adult Care Center 10/13/00-10/15/00
    22/30 clients with fever, nausea, and/or diarrhea
    3 hospitalized (see Patient Charts)
    No pets allowed in the facility. One of the hospitalized patients was a kitchen worker who prepared dessert for the clients. Water is delivered by a local company to the facility.

    Area of three outbreaks: within 20 miles of each other.

    1. doctor.jpg
    2. news.jpg
    3. virus.jpg
    4. scientist.jpg
    5. reader.jpg


    Student Products

    See next.

    Assessment and Evaluation Plan

    Lab report for the natural selection exercise (15%)



    Lab report for transformation experiment (30%)


    Lab report of model for bacterial growth and with antibacterial treatments (15%)

    Graph results

    Case-Based Investigation (40%)

    Students will create a group paper to include

    -the potential cause(s) of the three outbreaks
    -the mechanism of the illness
    -the best recommendation to decrease any further occurrences

    All groups will discuss their position for the cause of the outbreaks as well as debate the best way to decrease further occurrences.



    Course name:
    Likely sequence in syllabus:
    Time during term:
    Classroom and Lab
    Students in course:
    Majors and Non-majors
    Collaborative elements:
    Additional notes:




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