Outbreak investigation report

Agnes Hajdu

EpiTrain III, 25.08.2006Jurmala, Latvia

Based on EPIET material

Steps of an outbreak investigation

• Confirm outbreak diagnosis

• Define a case

• Identify cases and obtain information

• Descriptive data collection and analysis

• Develop hypothesis

• Analytical studies to test hypothesis

• Communication – Outbreak report

Control measures

Outbreak reports

First:

• What are they?

• Why write them?

• Who writes them?

• Who reads them?

Then:

• Structure

• Frequent problems

• Confidentiality

• Legal issues

What are outbreak reports?

• Formal outbreak reports – Preliminary, interim, final report

• Reports to colleagues – national bulletin, Eurosurveillance, conference/

seminars

• (Inter)national outbreak reporting systems

• Journal publications

Why write them?

• To document the outbreak– Present investigation methods, control

measures– Potential legal issue

• To verify recommendations• To enhance quality of investigations

In order to prevent future outbreaks and assist in investigation&control of similar incidents

Who writes them?

• ”The outbreak control team” (OCT)

• Named authors

• Each participating agency must agree with what is said

• Who ”owns” the report?

Who reads them?

• All agencies represented on the OCT

• Policy making bodies

• Professional colleagues

• The public

• The lawyers

Structure of the report

1. Summary2. Introduction and Background3. Outbreak description4. Methods 5. Results6. Discussion7. Lessons learned8. Recommendations9. References10. Appendices

1. Summary

• Key – Features, setting of the outbreak:

Who – What – Where – When?

– Lessons learned

– Recommendations

• Ongoing action

• Further action required

2. Introduction and Background

• Population demographics

• Surveillance data

• Previous similar outbreaks

• Description of the are/site/facility– e.g. Healthcare system

– e.g. Industries involved

– Any unusal point

3. Outbreak description

• ”The initial story”– How was the outbreak reported?

– Steps taken to confirm it?

– What was known to date?

• Why was an investigation undertaken?

• Management of the outbreak– OCT members, objectives, assistance, control

measures

• Media relations

4. Methods

• Epidemiological– Case definition, case finding, study design

(descriptive-analytical)

• Laboratory– Clinical and environmental specimens (types,

how they were collected)

• Environmental studies– Site visit and risk assessment, traceback

• Other studies

5. Results• Epidemiological

– Number of responses and participation rate– Number of cases– Overall attack rates and by age, sex, exposure– Symptoms, duration and outcomes of illness– Description (time, place, person)– Epidemic curve (incubation period)

• Laboratory findings• Environmental study findings

– Inspection report

• Other studies

6. Discussion

• Main hypotheses (likely causative agent and mode of transmission)

• Justify conclusions and actions– Clear interpretation of results

– Explain how results confirmed/disproved hypothesis

• Limitations, possible biases

• Explain action to protect public health

• Highlight any problems

7. Lessons learned

• Lessons for participating agencies– Problems encountered

– Mistakes made

– Suggestions for improvement

• Lessons that may be useful for others

• Key points from internal/external audit

8. Recommendations

• What should be done – To control this outbreak

– To prevent future outbreaks

– To improve management of future outbreaks

Be specific: to whom?

Be realistic: feasible actions

9. References

Vancouver referencing system

http://www.soton.ac.uk/library/subjects/references/vancouver.html

10. Appendices

• Chronology of events

• General background

• OCT (members, terms of reference)

• Detailed results

• Maps

• Epidemiological questionnaire

• Letters to patients/physicians

• Press releases

• Costs of the outbreak

• Acknowledgements

Problems

• Confidentiality– What should not be included?

• Legal issues

• Delay in writing the report

• Not writing the report at all..

Confidentiality

• To individual patients

• To commercial businesses

• Details may remain in meeting minutes

• Media disclosure

• Legal disclosure

Legal issues

• Who ”owns” the report / the data?

• Prosecuting agencies may deem the information to be confidential but…

… health authorities have a duty to provide the public with information

Report published

• Jan. 1997: outbreak report on MMWR:– Legionaire’s disease (LD) associated with

whirlpool spa on display, USA

• Febr. 1999: major outbreak LD, Holland– Source: whirlpool spa on display

– Lawsuit against government: failure to act on available knowledge (MMWR)

Conclusion

• Duty to – document the outbreak

– inform the colleagues

– prevent and control future outbreaks

• Good report = half publication– Write article, case study

Some reports stay alive

John Snow, 1843, Broad Street Pump Outbreak - Cholera