Session VI

Writing an Outbreak Report

Session Overview

1. Outbreak report function and critical components

2. Case studies– E. coli 0157:H7 at the NC State Fair, 2004– Multistate Outbreak of Monkeypox, 2003

Learning Objectives

• Understand the role of outbreak investigation reports

• Recognize the different types of reports

• Recognize elements to include in outbreak investigation reports

Basic Steps of an Outbreak Investigation

1. Verify the diagnosis and confirm the outbreak

2. Define a case and conduct case finding

3. Tabulate and orient data: time, place, person

4. Take immediate control measures

5. Formulate and test hypothesis

6. Plan and execute additional studies

7. Implement and evaluate control measures

8. Communicate findings

Why Communicate the Findings?

• Document for action• Share new insights• Record of performance• Substantiate recommendations

In order to…• Prevent future outbreaks• Assist in investigation and control of similar

incidents• Provide a document for potential legal issues

Why are Outbreak Reports Crucial to Public Health?

Example : Foodborne outbreak

• Hepatitis A contamination of green onions in TN, NC, GA, and PA, Sept-Nov 2003

• Food and Drug Administration (FDA) advisory report and MMWR alerted the public and assisted with traceback

Why are Outbreak Reports Crucial to Public Health?

Example: Respiratory disease outbreak

• Legionnaire’s Disease (LD) Associated with a Whirlpool Spa Display – Virginia, Sept-Oct 1996

• Case-patients were likely exposed by walking by or spending time near the spa

• The Virginia Department of Health issued recommendations for the inspection and maintenance of display spas

Why are Outbreak Reports Crucial to Public Health?

Example: Respiratory disease outbreak

• Legionnaire’s Disease (LD) outbreak at a flower show in the Netherlands, 1999

• Source: whirlpool spa on display

• Lawsuit raised against Dutch government for negligence

• Failure to act on available knowledge (MMWR 1996)

Some Reports are a Part of History

John Snow

Some Reports are a Part of History

Morbidity and Mortality Weekly Report (CDC), June 5, 1981

When is the Report Written?

• When the investigation is ‘complete’

• When the investigation is ‘ongoing’

– “Further analysis of data collected in this investigation may require revision of these findings and recommendations.”

– “Because of the preliminary nature of this investigation, future correspondence, MMWR articles, or other published reports might present results, interpretations, and recommendations that are different.”

Who Writes the Report?

• The field epidemiology / outbreak team– Visiting EIS officer

• Other authors as assigned

All participating agencies must agree with

what is in the report.

What are the Types of Reports?

• Complaint form• Internal report

– Record that outbreak occurred and investigation was conducted

• State publication – Newsletter, Website, statewide alert

• MMWR http://www.cdc.gov/mmwr/• Peer-Reviewed Journals

– Epidemiology and Infection, Emerging Infectious Diseases, Journal of Hospital Infection

Peer-Reviewed Articles

http://www.ncbi.nlm.nih.gov

Research Outbreak Updates

• MMWR mailing listwww.cdc.gov/mmwr/mmwrsubscribe

• FoodNetwww.cdc.gov/foodnet/

• ProMED-mail listserve www.promedmail.org

Basic Report Structure

• Summary• Introduction and Background• Outbreak Description• Methods and Results• Discussion• Lessons Learned• Recommendations• Acknowledgements

*Supporting Documentation

~ 2 - 3pages

Summary

• 1 - 2 paragraphs• Overview of the investigation

– WHO, WHAT, WHERE, WHEN, WHY/HOW• What caused the outbreak or the causal

hypothesis based on the evidence• Key recommendations• Ongoing actions• Pending / required actions

Introduction and Background

• Surveillance trends and similar outbreaks

• Include specific events that led to the investigation

- How the outbreak was first reported- Steps taken to confirm the outbreak- Those who became involved in the outbreak

investigation

• Description of the area / site / facility

Methods

• Epidemiologic– Case definition and ascertainment– Study design

• Microbiological / Toxicological– Clinical and environmental specimen collection– Where specimens sent– Types of analyses performed

• Environmental– Site visit & risk assessment– Traceback of food products or other items

Results

• Epidemiological – No. of questionnaires sent / returned– No. of cases and descriptive & clinical data

on cases– Geographic distribution of cases– Epidemic curve– Risk factor analysis– Attack rates by age, sex, exposure

Results

• Microbiological / Toxicological – Laboratory findings, e.g. genotyping, DNA

fingerprinting via PFGE, culture results

• Environmental– Results of any risk assessments– Results of any traceback investigation

Discussion

• Discuss main hypotheses

• Justify conclusions and actions

• Explain action to protect public health

Discussion

• Highlight any lessons learned

– Problems encountered

– Mistakes made

– Limitations of the study

– Useful lessons for planning future investigations

Recommendations• Control Measures

– To control this outbreak– To prevent future outbreaks– To improve management of future outbreaks

• Be specific about problems – Investigation obstacles and shortcomings– Outbreak causes

• Aim to educate fellow public health professionals and inform policy makers

Supporting Documentation

Also include the following:Graphs and tables

Inspection reports

Blank samples of surveys

Letters to management

Menus

Copies of posted notices

Testing results

Press releases

Maps

Case Studies

Case Study 1

Outbreak of E. coli O157:H7 at the North Carolina State Fair, 2004

Epi Notes, December 2004-February 2005http://www.epi.state.nc.us/epi/pdf/en2004-4.pdf

Case Study 1

• Condensed version of a more detailed report

• Includes all important components

– Outbreak description– Methods and results– Discussion– Lessons learned– Recommendations

Case Study 1

• October 2004: E. coli O157:H7 infection associated with state fair attendance.

• Case-control study design with 45 confirmed cases and 188 controls.

• Data analysis and public health laboratory results (PFGE) revealed petting zoo activities at the fair as the source of infection.

E. coli O157:H7 at the NC State Fair:Epidemic Curve

E. coli O157:H7 at the NC State Fair:Resulting Legislation

• “Aedin’s Law” - July 2005

• Permitting process and rules for animal exhibitions at state-sanctioned fairs

• Educational campaign about diseases associated with contact with animals

Case Study 2

Multistate Outbreak of Monkeypox – Illinois, Indiana, Kansas, Missouri, Ohio, and

Wisconsin, 2003

MMWR June 13, 2003

http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5223a1.htm

Multistate Monkeypox Outbreak Background and Outbreak Description

• CDC received reports of patients with a febrile rash illness in Illinois, Indiana and Wisconsin

• As of June 10, a total of 53 cases identified• Many reported close contact with pet prairie

dogs and other animals• Laboratory tests indicated the causative

agent was a poxvirus

Multi-state Monkeypox OutbreakMethods

• MMWR write-up includes combined data from multiple states– Methods are not detailed

• Laboratory investigation to identify the virus • Case-patient interviews to determine exposures,

symptoms, and obtain clinical specimens• Traceback investigation to identify original

source of illness

Multistate Monkeypox OutbreakLaboratory Results

• CDC tests concluded the virus was monkeypox

Multistate Monkeypox OutbreakEpidemiologic Results

Demographic information included in report:• 29 cases (49%) male• Median age 26 years (range: 4 - 53 years)• 14 cases (26%) hospitalized• Earliest onset of illness was May 15

Multistate Monkeypox Outbreak Epidemiologic Results

Multistate Monkeypox Outbreak Epidemiologic Results

Multistate Monkeypox OutbreakResults

Multistate Monkeypox Outbreak Results

• All patients had contact with animals• 51 of 53 cases reported direct or close contact

with prairie dogs • One patient reported contact with a Gambian

giant rat• One patient had contact with a rabbit that

became ill after exposure to an ill prairie dog at a veterinary clinic

Multistate Monkeypox OutbreakTraceback Results

• Common distributor - prairie dogs and Gambian giant rats housed together

• Imported animal records - Gambian giant rats shipped from Ghana to a wildlife importer in TX and sold to the distributor

• The shipment contained ~800 small mammals of 9 different species

Traceback Investigation

Multistate Monkeypox OutbreakDiscussion and Recommendations

• Preliminary findings suggested that the primary route of transmission is from close contact with infected mammalian pets

• However, the possibility of human-to-human transmission cannot be excluded

• Interim guidelines for infection control in the community and in health care settings were issued

Control Measure Guidelines

Comparison of Case Study Reports

• Both outbreak reports included the major elements:

– Introduction and Background– Outbreak Description– Methods and Results– Lessons Learned– Recommendations

• Complexity of the report depends on the type of investigation, the extent of the outbreak, and the audience of the report

Summary

• Outbreak reports are the final step in completing your investigation.

• Outbreak reports serve many purposes, both internally and externally.

• Though outbreak reports may differ in purpose and audience, reports generally follow a basic structure.

References and Resources• Ashford DA, Kaiser RM, Bates ME, Schutt K, Patrawalla A,

McShan A, Tappero JW, Perkins BA, Dannenberg AL. Planning against biological terrorism: Lessons from Outbreak Investigations. Emerg Infect Dis 2003;9:515-9.

• Conducting an Outbreak Investigation. The North Carolina Communicable Disease Control Manual, North Carolina Division of Public Health. Accessed at http://www.epi.state.nc.us/epi/gcdc/manual/outbreakinvest.pdf

• Consumers Advised That Recent Hepatitis A Outbreaks Have Been Associated With Green Onions. FDA Talk Paper. November 15, 2003. Assessed 10/13/2004 http://www.fda.gov/bbs/topics/ANSWERS/2003/ANS01262.html

• Den Boer JW, Yzerman PF, Schellekens J, et al. A large outbreak of Legionnaires’ disease at a flower show, the Netherlands, 1999. Emerg Infect Dis 2002;8:37-43.

References and Resources• Fontham ETH, Correa P, Wu-Williams A, Reynolds P, Greenberg

RS, Buffler PA, et al. Lung cancer in nonsmoking women: a multicenter case-control study. Cancer Epidemiol Biomarkers Prev 1991;1:35-43.

• Gaudet, M. (2003). Suggestions for Critically Evaluating an Epidemiologic Study Report. Handout developed for the UNC Chapel Hill School of Public Health EPID 160 course “Principles of Epidemiology.”

• Goode B. Outbreak of E. coli 0157:H7 at the North Carolina State Fair – 2004. EpiNotes, North Carolina Department of Health and Human Services, Division of Public Health. Accessed at http://www.epi.state.nc.us/epi/pdf/en2004-4.pdf

• Gordis, L. Epidemiology. 2nd ed. Philadelphia: WB Saunders Company; 2000.

References and Resources• Greenberg RS, Daniels SR, Flanders WD, Eley JW, Boring JR.

Medical epidemiology. 3rd ed. New York: McGraw-Hill; 2001.

• Guidelines for EPI-AID Investigations. Division of Applied Public Health Training, Epidemiology Program Office, CDC.

• Hepatitis A Outbreak Associated with Green Onions at a Restaurant --- Monaca, Pennsylvania. MMWR 2003;52(47);1155-1157

• International Committee of Medical Journal Editors. Uniform requirements for manuscripts submitted to biomedical journals: writing and editing for biomedical publication. Updated November 2003. http://www.icmje.org/ Accessed August 19, 2004.

• Last JM, editor. A dictionary of epidemiology. 4th ed. Oxford University Press; 2001.

References and Resources• Levine, S. Redinger, C. and Robert, W. (September / October

2001). Community Exposure Assessment and Intervention Effectiveness at Trinity American Corporation, Glenola, North Carolina. American Industrial Hygiene Association Journal. 62: 649-657.

• Massachusetts Foodborne Illness Investigation and Control Reference Manual. http://www.state.ma.us/dph/fpprefman.htm

• Millikan B. How to read a scientific article. http://cbcs.med.unc.edu/howto.htm Accessed July 26, 2004.

• Pneumocystis Pneumonia – Los Angeles. 1981 MMWR 30(21);1-3.

• PubMed database, National Library of Medicine. Available online at http://www.ncbi.nlm.nih.gov/entrez/query.fcgi

• Reigelman RK. Studying a study and testing a test: how to read the medical evidence. 4th ed. Philadelphia: Lippincott Williams & Wilkins; 2000.

References and Resources

• Rothman KJ. Modern epidemiology. Boston: Little, Brown and Company; 1986.

• Savitz DA. Interpreting epidemiologic evidence: strategies for study design and analysis. Oxford University Press; 2003.

• The Outbreak Investigation Report, power point presentation by Arnold Bosman and Meirion Evans. Epiet. Accessed at www.epiet.org/course/presentations2003.html

• Update: Multistate Outbreak of Monkeypox – Illinois, Indiana, Kansas, Missouri, Ohio, and Wisconson, 2003. MMWR 52(23);537-540

• Zhong L, Goldberg MS, Parent M, Hanley JA. Exposure to environmental tobacco smoke and the risk of lung cancer: a meta-analysis. Lung Cancer 2000;27:3-18.