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EIS Case Studies

Epidemic Intelligence Service (EIS) Officers in classroom.

Epidemic Intelligence Service (EIS) Officers learn applied epidemiology through a CDC case study.

Case Studies in Applied Epidemiology

CDC developed case studies in applied epidemiology based on real-life epidemiologic investigations and used them for training new Epidemic Intelligence Service (EIS) officers — CDC’s “disease detectives.” EIS offers these carefully crafted epidemiology case studies for schools of medicine, nursing, and public health to use as a component of an applied epidemiology curriculum.

The following case studies use specific examples to teach epidemiology concepts, require active participation, and help strengthen problem-solving skills. These case studies in applied epidemiology:

Cover epidemiologic basics, including:

Outbreak investigation
Surveillance
Study design
Data interpretation
Descriptive and analytic methods

Are based on public health investigations of:

Infectious diseases
Chronic illnesses
Environmental health

Instructor and Student Guides

Each EIS Case Study consists of an instructor guide or a student guide.

Instructors or trainers (not students): ask for Applied Epidemiology Applied Epidemiology Case Studies instructors’ guides. Send an e-mail to: EISoperations@cdc.gov and label subject line: “Case Study Instructor Guide Request”.
Students: Use Adobe Acrobat reader, to view or print the student guides.

How to Use the EIS Case Studies

Students may practice their epidemiologic skills by using these exercises in classroom activities or as homework assignments to reinforce principles and skills previously covered in lectures and reading assignments.

In-Class Activity
Students, read the case study up to the first question and then perform calculations, construct graphs, or discuss the answer. Students may be asked to play different roles in answering the question. After discussing the first answer satisfactorily, read on to the next question and continue with the exercise.
Individual Activity
Students, for a homework assignment, read the case study and answer the questions, then discuss the findings in class.

Student Guide #873-703 [PDF – 16 pages]. Case study based on a 1985 outbreak with unknown etiology and mode of transmission in multiple states. Updated in 2003.

Learning Objectives

After completing this case study, students should be able to

List the key tasks involved in investigating epidemics of unknown cause
Describe the roles, responsibilities, and relationships of federal versus state public health agencies in a field investigation
Assign appropriate priority to key tasks during an investigation
Describe jurisdictions of health agencies at various levels of government

Student Guide #731-703 [PDF – 12 pages]. Case study based on the classic studies of Doll and Hill in the 1950s. Addresses study design, interpretation of measures of association, and impact of association. Updated in 2003.

Learning Objectives

After completing this case study, students should be able to

Discuss the elements of study design, and the advantages and disadvantages of case-control versus prospective cohort studies
Discuss some of the biases which might have affected these studies
Calculate a rate ratio, rate difference, odds ratio, and attributable risk percent
Interpret each measure and describe each measure’s use
Review the criteria for causation

Student Guide #811-705 [PDF – 15 pages]. Case study based on a 1980–1982 multicenter case-control study. Addresses bias and analysis of case-control studies. Updated in 2005.

Learning Objectives

After completing this case study, students should be able to

Outline the sequence of an epidemiologic analysis
Discuss the biases of particular concern in case-control studies and ways to minimize their influence
Describe why and when to use crude and adjusted odds ratios and 95% confidence intervals, and how to interpret them
Define and recognize effect modification and confounding

Student Guide #401-303 [PDF – 12 pages]. Case study of a classic, straightforward outbreak investigation in a defined population. Based on a 1940 outbreak of Staphylococcus aureus among church picnic attendees. Additional material: Compendium of Acute Foodborne and Waterborne Diseases [PDF – 7 pages]. Updated in 2003.

Learning Objectives

After completing this case study, students should be able to

Define the terms cluster, outbreak and epidemic
List the steps in the investigation of an outbreak
Draw, interpret and describe the value of the epidemic curve
Calculate and compare food-specific attack rates to identify possible vehicles
List reasons for investigating an outbreak that has apparently ended

Student Guide #891-903[PDF – 11 pages]. Case study of a surveillance system. Updated in 2003.

Learning Objectives

After completing this case study, students should be able to

Define incidence, prevalence, and case-fatality rate
Define surveillance and identify the key features of a surveillance system
List the types of information that should be collected on a surveillance case report form
List the factors that can account for a change in the reported incidence of a disease
Define sensitivity of a surveillance system, and the effect of different case definitions on sensitivity

Student Guide #731-705 [PDF – 12 pages]. Case study of a hypothetical health department anticipating the release of the first HIV antibody test in 1985. Focus is on screening. Updated in 2003.

Learning Objectives

After completing this case study, students should be able to

Define and perform calculations of sensitivity, specificity, predictive-value positive and predictive-value negative
Describe the relationship between prevalence and predictive value
Discuss the trade-offs between sensitivity and specificity
List the principles of a good screening program

Student Guide #912-303 [PDF – 16 pages]. Case study based on a community outbreak of Legionnaires’ disease in Bogalusa, Louisiana in 1989. Addresses the steps of a field investigation and a case-control study.. Updated in 2003.

Learning Objectives

After completing this case study, students should be able to

Discuss the relationship between and roles of state-based and Atlanta-based EIS officers in a field investigation
Develop an epidemiologic case definition
Calculate power for a case-control study
Describe different sources of controls for a community-based outbreak

Student Guide #941-903 [PDF – 19 pages]. Case study based on surveillance and investigation activities of the Oregon Health Division between 1986 and 1995. Updated in 2003.

Learning Objectives

After completing this case study, students should be able to

List the process and criteria for placing a disease or condition on a state or national notifiable disease list
List the categories of information that should be included in a surveillance instrument
Summarize and interpret surveillance data
Recognize difficulties in balancing public health concerns with consumer and industry considerations in emerging issues

Student Guide #711-903 [PDF – 12 pages]. Case study based on an infectious disease outbreak investigation in Texas.

Learning Objectives

After completing this case study, students should be able to

Discuss the advantages and disadvantages of using a sensitive and/or specific case definition in an epidemic investigation
Calculate vaccine efficacy and discuss its interpretation
Discuss the advantages and limitations of selecting a specific age as the recommended target date for administering vaccinations

The fellowship application period is open now through June 5, 2024.

The host site application period is now closed.

For questions, please contact the EIS program directly at EISOSupport@cdc.gov.

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