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Case Investigation of Avian Influenza. Rapid Response Team Training in Southeast Asia. Learning Objectives. Describe and conduct pre-investigation activities Demonstrate knowledge of key epidemiologic concepts in field investigations Describe how to communicate epidemiologic findings

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case investigation of avian influenza

Case Investigation of Avian Influenza

Rapid Response Team Training in Southeast Asia

learning objectives
Learning Objectives
  • Describe and conduct pre-investigation activities
  • Demonstrate knowledge of key epidemiologic concepts in field investigations
  • Describe how to communicate epidemiologic findings
  • Describe how to appropriately assess and respond to potential outbreak situations
case investigation module format
Case Investigation Module Format
  • Interactive case studies and instructional slides
  • Rapid response team (RRT) investigation of avian influenza cluster or case
  • Evaluation of an RRT avian influenza investigation
  • Groups of 10 to conduct investigation
module overview

Planning the Response


Case Definition

Specimen Collection

Case Finding


Contact Identification

After the Investigation

Evaluate Performance


Data Management

Creating an Epidemic Curve

Assessing Transmission

Writing a Summary Report

Module Overview
pre investigation


Before you leave to investigate

pre investigation gather preliminary information
Pre-Investigation:Gather Preliminary Information

Assess the situation

  • Information to collect:
    • Number of suspected cases
    • Geographic location of cases
    • Date of onset of cases
    • Signs and symptoms
    • Exposure history – contact with birds, travel, occupational
    • Lab tests
  • Consider the security situation in the area
pre investigation plan the response
Pre-Investigation:Plan the Response
  • Bring RRT together
    • Refer to Team Composition module for roles and responsibilities of RRT members
  • Discuss each person’s roles and responsibilities
pre investigation documentation
  • Information already gathered
    • Location of case, date of illness onset, clinical or exposure details
  • List of contacts
  • Case reporting forms
  • Standardized questionnaires
pre investigation resources
  • People
    • Local health workers caring for case-patient
    • Veterinarians, clinical and laboratory experts, support personnel
  • Ministry of Health
    • Advice, guidance, additional personnel
  • World Health Organization (WHO)
  • Avian influenza references
  • Other
    • Transportation
    • Security
    • Communication devices
    • Money
pre investigation supplies
  • Epidemiological
    • Reporting forms
    • Notebook (or laptop) for recording data
  • Medical
    • Antiviral medication (if available)
  • Laboratory
    • Swabs, needles, cooler, ice, viral transport media
pre investigation supplies11
Pre-Investigation: Supplies
  • Educational
    • Brochures, posters, with influenza safety information
    • Easy to read
    • Guidelines for contacts, family members
  • PPE
    • Masks, gloves, gown, cap, goggles
  • Decontamination
    • Solution for decontaminating homes or hospital rooms
pre investigation communication
Pre-Investigation: Communication
  • Veterinary Health Authority
  • Government Officials
  • Health Care personnel
  • Community
  • Non-governmental organizations
  • Laboratory
case study pre investigation

Case StudyPre-Investigation

Before you leave to investigate

case study pao mai province
Case Study: Pao Mai Province
  • Province located in northern part of country
  • Peaceful region with little political instability
  • Many earn income through backyard chicken farming
  • Poor Infrastructure
  • Ratio of physicians

to population

is 1:5,000


objectives of a rrt investigation
Objectives of a RRT Investigation
  • Assess the possibility of human-to-human transmission
  • Stop or slow the spread of pandemic influenza at the source
  • Minimize mortality and morbidity
steps in rapid response investigation
Steps in Rapid Response Investigation
  • Conduct active case finding
  • Identify and follow-up with contacts
  • Collect samples for laboratory tests
  • Characterize illness and provide descriptive epidemiology
  • Investigate reservoir or source of infection
  • Report cases to provincial authorities
  • Implement immediate containment measures
investigating a suspect case
Investigating a Suspect Case

Evidence for H5N1 infection based on

  • Clinical findings
  • Epidemiological evidence
  • Laboratory testing
case definitions20
Case Definitions
  • “Standardizes” the investigation
  • Clear criteria for being a case (symptoms or lab results)
  • Is unique to outbreak but is based on objective measures
case definition
Case Definition

Categories of case definitions for avian influenza A/H5

  • Patient under Investigation
  • Possible Case
  • Probable Case
  • Confirmed Case
case definitions for influenza a h5
Case Definitions for Influenza A/H5

Patient Under Investigation

  • Any individual reporting:
    • Fever (temperature above 38º C)

And one or more of these symptoms

    • Cough
    • Sore throat
    • Shortness of breath
case definitions for influenza a h523
Case Definitions for Influenza A/H5

Possible Case

  • A “patient under investigation” who ALSO has one or more of the following:
    • Lab test for Influenza A (not including subtype)
    • Contact in past 14 days with confirmed case of Influenza A/H5
    • Contact in past 14 days with sick birds
    • Worked in lab where there is processing of samples from persons/animals with Influenza A
case definitions for influenza a h524
Case Definitions for Influenza A/H5

Probable Case

  • Any “patient under investigation” or possible case who ALSO has
    • In-country laboratory evidence for influenza A/H5
case definitions for influenza a h525
Case Definitions for Influenza A/H5

Confirmed Case

  • Laboratory testing demonstrates 1 or more of following
    • Positive viral culture for A/H5
    • Positive PCR for A/H5
    • IFA Test positive for A/H5
    • At least 4-fold rise in A/H5 in paired serum samples
case study background
Case Study: Background


  • A staff doctor at Pao Mai Provincial Hospital notifies the Provincial Health Office that they have admitted 2 previously healthy persons with severe respiratory illness.
  • The doctor is concerned that his patients may have avian influenza, as there are rumors that poultry outbreaks are occurring all over the province.
activity a is there an outbreak brainstorm and role play 25 minutes
Activity A: Is there an outbreak?Brainstorm and Role Play25 Minutes
  • If you had received this call, what additional information would you want to receive from the treating physician?
  • What would the conversation between the physician and the RRT member sound like? Conduct a role play
background on cases
Background on Cases


  • Two cases are related
    • A 55 year-old grandmother
    • Her 5 year-old grandson
  • The cases reside in the same house with the child’s grandfather in a small mountain village
  • The grandmother is the child’s primary caretaker
  • The child was brought to the hospital two days ago with the following symptoms: fever, cough, diarrhea and shortness of breath
background case history
Background: Case History


  • Shortly after admission on July 11th, the child rapidly decompensated requiring intubation and ventilatory support
  • His grandmother was by his bedside when she also became ill.
  • Child’s mother lives outside the province but arrived at hospital yesterday.
  • Child’s grandfather denies symptoms.
  • The treating physician requests assistance from public health authorities
Activity B: Plan the ResponseBrainstorm and Group DiscussionI. Logistics and DocumentationII. Communication

You must plan how you will respond to the situation before you leave for the field.

pre deployment activity logistics and documentation
Pre-Deployment Activity: Logistics and Documentation
  • Who are the members of the team?
  • Where will you go?
  • How will you get there?
  • What is the security situation?
  • What documentation do you need to bring with you? What forms will you need?
  • What resources and supplies will you need to bring with you? Where will you obtain the resources?
pre deployment activity communications plan
Pre-Deployment Activity Communications Plan


Who do you need to communicate with before you depart for the field?

Who on your RRT is responsible for communicating with agencies and the media?

Will there be communication/cultural barriers when you arrive in the field?

How will you communicate with each other in the field?

activity c case definition group discussion
Activity C: Case Definition Group Discussion

JULY 14th

  • Your RRT arrives at Pao Mai and goes directly to the hospital to begin the investigation.
  • The available medical charts and chest x-rays for the suspect AI cases are provided to the RRT.
case definition exercise group discussion activity
Case Definition Exercise Group Discussion Activity

Using the data in Trainee Activities, address the questions provided below:

  • Do the cases meet case definition?
    • If so, how would they be classified?
  • Is any additional information needed to classify cases? If so, what?
  • How would case #2 move from its current classification to the next?
specimen collection

Specimen Collection

Confirm the Diagnosis

review laboratory module
Review Laboratory Module
  • How to safely and correctly collect specimens
    • Who to collect from
    • What samples to collect
    • What to wear
    • How to transport specimen
    • Procedures for diagnosis
what to collect
What to Collect

Preferred specimens

  • Nasal swabs
  • Throat swabs
  • When possible: Nasopharyngeal aspirates

Other specimens

  • Posterior pharyngeal swabs
  • Nasal washes
  • Acute and convalescent serum

Collect the sample on several different days

laboratory testing
Laboratory Testing

If positive test for Influenza A and/or suspicion of avian influenza:

Sub-type at in-country laboratory

Non-approved laboratories

Forward samples to National Influenza Centre

Inform WHO Office in country

Confirmatory testing should be conducted at a WHO approved laboratory

why is case finding important
Why is Case Finding Important?
  • Ensure you have identified as many cases as possible
  • Case finding may provide information about human-to-human transmission
  • Any cases related in time and space to initial cluster or case
how to find cases
How to Find Cases
  • Consider all possible symptomatic persons as cases at the beginning of an investigation
    • Visit health facilities, homes of neighbors and adjacent communities
    • Public information messages in the affected communities
common challenges to case finding
Common Challenges to Case Finding
  • Even with case finding, all cases may not be identified
    • Physician may not suspect avian influenza
    • Some infected persons may not seek medical attention

What are some other potential barriers to finding cases in the Pao Mai Province?

who to interview
Who to Interview
  • Case-patient
  • Family members/Household contacts
  • Health care providers/Lay health workers
interview tips
Interview Tips
  • Collect as much information as possible
    • Unstructured interviews
    • Generate list of contacts
  • Repeat critical questions for accuracy, validity and additional details
interview tips47
Interview Tips
  • Be friendly, but professional
  • Identify yourself and your institution
  • Explain purpose of interview
  • Stress importance of information you will collect
  • Inform respondents that all information will be kept confidential
  • If appropriate, conduct interview in private
type of information to collect
Type of Information to Collect
  • Demographic information: age, sex contact details
  • Clinical information: signs & symptoms, physical exam, vitals, date of onset, hospital admission
  • Exposure history: occupational exposure, travel, animal exposure
activity d specimen collection
Activity D: Specimen Collection
  • What specimens need to be collected?
  • What specimens should have already been taken from the cases? When should any additional specimens be taken?
  • Should specimens be collected from the child’s grandfather?
  • What PPE does the nurse need to wear when collecting specimens from the child?
activity e case finding group discussion
Activity E:Case Finding Group Discussion
  • How would the RRT find out if there are additional cases?
  • Consider the following:
    • Locations/settings for case finding
    • Who you might like to interview
    • Questions the RRT would ask potential cases
    • Need for PPE while conducting interviews
case finding interview activity role play
Case Finding Interview ActivityRole-Play
  • See one, do one and teach one!
    • Observe a case finding interview
    • Select a partner and take turns practicing the administration of a standardized case finding questionnaire.
    • After completing the questionnaire, critique each other’s performance.
what is contact identification
What is Contact Identification?

The identification and diagnosis of persons who may have come into close contact with an infected individual

purpose of contact identification
Purpose of Contact Identification
  • Find new cases that meet case definition
  • Provide interventions for exposed individuals to decrease risk of illness and interrupt further transmission
    • Antivirals (Oseltamivir)
    • Precautionary Information
how to identify contacts
How to Identify Contacts
  • Review patient’s activities for the 7 days before onset of symptoms

2. Based on activities, identify all close contacts (within 1 meter)

3. Verify all information collected

key information to gather
Key Information to Gather
  • Who did case come into close contact with?
  • What activities was case doing?
  • Where did this take place?
  • When did case come into contact with this person?
  • Contact’s Address and Phone Number
  • Contact’s Health Status
  • Contact’s Gender, Occupation, Age
general guidelines for interviewing contacts
General Guidelines for Interviewing Contacts
  • Do not alarm contacts
  • Communicate precautionary information
  • Refer symptomatic individuals to clinic
  • Consider if Personal Protective Equipment is necessary
information to gather from contact
Information to Gather from Contact
  • Demographic and contact information
    • Name, Address
    • Occupation, age, gender
  • Exposure History
    • Contact with case-patient
    • Other high-risk exposures
  • Physical Exam and Clinical information
    • Temperature
    • Presence of sore throat, coughing
    • Signs and symptoms
monitoring and managing contacts
Monitoring and Managing Contacts
  • Monitor for signs of illness for at least 7 days after contact with case
    • Encourage self-health monitoring
    • Instruct to report onset of symptoms
    • Visit or phone daily to monitor for illness
  • Request voluntary home quarantine of all contacts for at least 7 days
  • Consider antiviral prophylaxis
prioritize contact identification
Prioritize Contact Identification
  • If number of contacts is large focus on:
    • Contacts of laboratory confirmed cases
    • Contacts with extended duration and closeness to case
    • Contacts that are at high risk, such as those involved in unprotected care of case
    • Contacts from large gatherings and/or school that case attended
inform those who need to know
Inform Those who Need to Know
  • Local Level
  • National Level
  • International Level
inform those who need to know64
Inform Those who Need to Know
  • Insert Local and/or National Reporting Requirements (country-specific)
inform those who need to know65
Inform Those who Need to Know
  • International Health Regulations (IHR)
    • Compulsory notification of highly-pathogenic strains of avian influenza
    • Vaccination and food safety of poultry products
  • Compliance with these standards is required to strengthen early detection, reporting, and response
activity g contact identification group discussion
Activity G:Contact Identification Group Discussion
  • Develop a village-based system to monitor and manage contacts. Address:
    • What is your definition of a close contact?
    • Who will receive prophylaxis, if available?
    • How long should contacts remain at home voluntarily during quarantine?
    • Monitoring contacts for signs of illness
activity h reporting
Activity H:Reporting

Discussion Questions

Local Level: Who is responsible for submitting AI case reports? When should this be done?

reporting activity
Reporting Activity

Discussion Questions:

National Level: Who in your country needs to be updated on the progress of the investigation and receive the final report on number of cases? Who is responsible for assuring that this occurs?

reporting activity70
Reporting Activity

Discussion Questions:

International Level: What international agencies need to be informed of suspect human cases? Who in your country is responsible for notifying international authorities?

data management
Data Management
  • Line listing
  • Record keeping
  • Validation and Cross-Checking
line listing
Line Listing

An organized way to view all cases in an investigation




Information included:

how to create a line list
How to Create a Line List
  • Add new cases as they are identified
  • Update case information throughout the investigation
  • Number of variables to include will depend on available data, nature of investigation
how to create a line list75
How to Create a Line List

Always include:

  • Components of case definition
  • Case name, identifying number
  • Date of symptom onset, specimen collection date

May also include additional information:

  • Age, gender, occupation, risk factors
how to create a line list76
How to Create a Line List
  • Create a table in which each row represents a case and each column represents a variable of interest
    • Variables: Demographics (age), symptoms, exposures
record keeping
Record Keeping
  • Where will records be kept?
  • How will records be kept?
  • Who is assigned to record keeping?
  • Maintain confidentiality
validation and cross checking
Validation and Cross-Checking
  • Check line lists against medical charts and interviews
  • Validation
    • Ask same question in different ways
    • Ask same question at different times
    • Ensure answers are consistent
what is an epidemic curve and how can it help in an outbreak
What is an Epidemic Curve and How Can it Help in an Outbreak?

An epidemic curve (‘Epi’ curve) is a graph or picture of the number of cases of illness by the date of illness onset

what is an epidemic curve and how can it help in an outbreak81
What is an Epidemic Curve and How Can it Help in an Outbreak?

Provides information characteristics of an outbreak:

  • Magnitude
  • Pattern of spread
  • Outliers (case outside expected time frame)
  • Time trend
  • Exposure and/or disease incubation period
how do i make an epi curve
How do I Make an Epi Curve?
  • Plot the number of cases of disease reported during an outbreak on the y-axis
  • Plot the time or date of illness onset on the x-axis
how do i make an epi curve83
How do I Make an Epi Curve?
  • Technical tips
    • Time unit for x-axis depends upon the time from exposure to illness onset (incubation period)
    • Begin with a unit approximately one quarter the length of the incubation period
    • If the incubation period is not known, graph several epi curves with different time units
how do i make an epi curve84
How do I Make an Epi Curve?
  • Usually the day of illness onset is the best unit for the x-axis
    • If the incubation period is very short, hour of onset may be more appropriate
    • If the incubation period or outbreak is very long, week or month may be more appropriate
how do i make an epi curve85
How do I Make an Epi Curve?
  • No space between

categories on the x axis

  • Label each axis
  • Provide a descriptive title
  • Include the pre-epidemic period to show the baseline number of cases
activity i linelist cross checking exercise
Activity I:Linelist & Cross-checking Exercise

July 15th

  • An incomplete linelist and an update on the status of the Pao Mai outbreak is provided in your student guide
  • Find any errors in the completed sample linelisting provided in your student guide.
activity j epidemic curve activity
Activity J:Epidemic Curve Activity

Create an epidemic curve using the data from the case study

(Summary data on next slide)

summary of data from case study
Date of Onset

(When symptoms began)

July 7th

July 8th

July 9th

July 10th

July 16th

Number of Cases

1 confirmed (Case #3)

1 confirmed (Case #1)

2 possible (Cases #5 & #6)

1 probable (Case #7)

1 confirmed (Case #4)

Summary of Data from Case Study
discussion questions
Discussion Questions

Based on this epi curve:

  • What is the estimated incubation period?
  • When did the outbreak peak according to the epi curve?
  • Are there any outliers? If so, what might explain them?
current status of h5n1 transmission
Current Status of H5N1 Transmission
  • Now
    • Human-to-human transmission of Influenza A/H5 highly ineffective
    • Has occurred only among very close contacts
  • In the future
    • Virus could mutate and pass between humans
    • Global outbreak could occur
assessing human to human transmission94
Assessing Human to Human Transmission
  • Cases occur close together in time and place among individuals who had close contact with a human case
    • Family members or health care workers
  • Onset between two cases falls within the incubation period
  • No alternative source of exposure is found
when a cluster may exist
When a Cluster May Exist

3 or more people with moderate or severe acute respiratory illness

Unexplained by other causes

May have died from the illness

Onset within 7-10 days of each other


History strongly suggesting exposure to H5N1 virus

epidemic curves and transmission
Epidemic Curves and Transmission

Assess whether human-to-human transmission is occurring

  • Epi curve pattern for infectious agent transmitted between people
  • Epi curve pattern for infectious agent transmitted from one source to people
outbreak ends in pao mai
Outbreak Ends in Pao Mai

1 September 2006

  • H5N1 cases identified = 6
  • RRT interviewed 52 possible case contacts
    • 96% of these received antiviral prophylaxis
  • Deaths = 5
  • Case Fatality Rate = 83%


why communicate the findings
Why communicate the findings?
  • A document for action
    • Control and prevention measures
  • To share new insights
  • Documents the investigation
  • To assist other nations districts or countries with investigation
  • Inform the public
    • Prevents future outbreaks
content of a summary report
Content of a Summary Report
  • Summary
  • Introduction and Background
  • Outbreak Description
  • Methods and Results
  • Discussion
  • Lessons Learned
  • Recommendations
  • Acknowledgements
  • Supporting Documentation
activity k assessing human to human transmission
Activity K:Assessing Human to Human Transmission

Which are likely human-to-human transmission? Why?

  • 5 year-old child
  • 13 y.o. female neighbor of farmer
  • Poultry farmer
  • Farmer’s apprentice
  • Physician at Pao Mai Hospital
  • 82 y.o. female neighbor of family cluster
activity k assessing human to human transmission problem solving
Activity K:Assessing Human to Human Transmission: Problem Solving

Review the four scenarios in your guide and consider the possibility of human to human transmission for each.

activity l summary report activity
Activity L: Summary Report Activity
  • Fill out the WHO daily situation report.
  • Over the outbreak, these reports can be used to create a summary report.
why evaluate the investigation
Why Evaluate the Investigation
  • To summarize the events that occurred
  • To learn from experience
    • Make recommendations for future investigations
    • Take lessons from what worked well
    • Take lessons from mistakes
what to evaluate
What to Evaluate
  • Timeliness of response
  • Completeness of the investigation
  • Accuracy of the data
timeliness of deployment
Timeliness of Deployment
  • Response time

Notification Arrive at location

  • Ideal: about 24 hours
  • Delays
    • Assembling team
    • Finding supplies
    • Getting to location
  • How could response time be improved?
timeliness investigation and initial assessment report
Timeliness: Investigation and Initial Assessment Report

Arrival in field Deliver initial assessment report

  • Initial report
    • Oral or written
    • May receive feedback on how to proceed
  • Delays
    • Interviews, initial investigation
    • Poor communication in team
    • Too busy
timeliness investigation and final assessment report
Timeliness: Investigation and Final Assessment Report

Arrival in field Deliver final assessment report

  • Final report
    • Oral or written
    • Summary and recommendations
  • Delays
    • Follow-up interviews
    • Containment measures
    • Poor data management
timeliness final report
Timeliness: Final Report

End of field Official investigation investigation report

  • Official record of investigation
  • Delays
    • Back to “normal” work
    • Lack of motivation
  • Necessary activities completed?
    • Team assembled and worked well
    • Interviews
    • Case definitions
    • Data collection
    • Reports
  • Data collected from questionnaires complete?
accuracy of data
Accuracy of Data
  • Data management
  • Validation and cross checking
  • A report based on incomplete or inaccurate data is not informative!
sars outbreak april 2004
SARS Outbreak April 2004
  • 10 April, 2004
    • A woman in Anhui province, Eastern China, has been admitted to the hospital with severe respiratory symptoms and fever
    • Another patient in the hospital develops similar symptoms
  • 12 April, 2004
    • The woman is suspected of having SARS and is transferred to a hospital in Beijing
    • A rapid response team is deployed to investigate this patient, her exposures, and her contacts
summary report may 2 2004
Summary Report: May 2, 2004


This section describes when the case first presented to the hospital and how the ministry of health was informed of the possibility of SARS


Here the team described the hospitals visited in Beijing and Anhui province, the interviews they conducted, and the medical research laboratory they visited.

Outcome and Control Measures.

In this section, the team described the number of additional cases and contacts they found, their status, and what control measures were put into place to control the outbreak. This included isolating nearly 160 exposed persons and temporarily closing the research laboratory.


In this section, the team describes the good and bad points of their investigation, and makes recommendations for preventing future outbreaks and for making future outbreak investigations better.


Activity M:Evaluate Group Performance Group Discussion

Review and critique these documents from an investigation:

  • Completed questionnaire from interview with index patient
  • Linelistings of Cases and Contacts
  • The summary report for the investigation


An organized list of all cases in an outbreak investigation that shows key characteristics for each case, including demographic, clinical, and exposure information.

Epidemic Curve (Epi curve)

A graph (histogram) of the number of cases of illness on the y-axis by the date of illness onset on the x-axis. Time intervals on the x-axis will vary by disease and incubation period.


Any value that is markedly smaller or larger than other values in a data set.

Contact identification / Contact tracing

The identification and medical assessment of persons who may have come into close contact with an infected individual.


Case finding

The process of determining if more cases of a particular disease under investigation exist.

Case definition

A set of objective criteria for who should be considered a case and who should not, often including a list of symptoms or results from laboratory tests.

Incubation period

The time interval between the initial exposure to infection and the appearance of the first symptom or sign of disease.

references and resources
References and Resources
  • WHO pandemic influenza draft protocol for rapid response and containment. Updated March 2006.
  • Epidemiology of WHO-confirmed human cases of avian A(H5N1) infection. June 2006, Weekly Epidemiological Record vol. 81(26): 249–260.