Epi-Ready - NEHA CERT Online Education

Transcription

Table of Contents
Acknowledgements
Epi-Ready Team Training
Module 1: Passive Surveillance
Task List
Module 1 PowerPoint Presentation
Table 1: Foodborne, waterborne, enteric illnesses log
Module 2: Outbreak Determination
Task List
PowerPoint Presentation
Interviewing Group Exercise: A Potential Outbreak?
Interviewing Group Exercise: Interview Evaluation
Module 3: Environmental Assessment
Task List
Module 4: Epidemiologic Investigation
Task List
Case Definition and Hypothesis Exercise
Group Exercise: Joe’s Thanksgiving Dinner
IAFP Form A
IAFP Form C1 and C2
Module 5: Laboratory Guidance
Task List
Kit Contents for Collecting Samples During Investigation of Foodborne
Outbreak
Sources, Materials for Foodborne Disease Investigation Kits
Module 6: Outbreak Concluding Actions
Task List
Example Report Template
Example Final Report - Maple Rapids Church Youth Group Program
Campylobacter jejuni Outbreak
Final Exercise: A Case Study – Multistate Outbreak of E. coli 0157:H7
Appendices:

Appendix 1: Foodborne Illness Glossary

Appendix 2: Communications
1. Preparation
2. Outbreak Response
3. Termination

Appendix 3: Interviewing Skills
1. Task List
2. Task List Related Information

Appendix 4: Forms
1. Food Preparation Review
2. CDC Form 52.13/Spoon and Fork/EFORS
3. IAFP Form A
4. IAFP Form C1
5. IAFP Form C2

Appendix 5: Web-based Resources to Explore

Appendix 6: Answer Sheets
1. Graduation Party Blues Exercise
2. Joe’s Thanksgiving Dinner Group Exercise
ACKNOWLEDGEMENTS
Epi-Ready Team Training reflects the efforts of many dedicated individuals, and foremost the
Michigan Foodborne Illness Response Strategy (F.I.R.ST.) Workgroup who designed and
successfully implemented this course in Michigan, and encouraged NEHA to utilize their course
as the framework for Epi-Ready Team Training. Individuals on the F.I. R.S.T. Workgroup include
Jennifer Beggs, Sally Bidol, Tom Buss, Joann Clinchoc, Janet Dorer, Sonja Hrabowy, Siobhan
Kent, Whitney Mauer, Cindy Overkamp, Doug Park, Susan Shiflett, and John Tilden.
NEHA’ s Epi-Ready Team Training course is made possible through a cooperative agreement
with the Centers for Disease Control and Prevention, National Center for Infectious Diseases
(CDC/NCID)-Food Safety Office. Special thanks go to Dr. Arthur P. Liang, Dr. Donald J. Sharp,
and Richard Skibicki.
Epi-Ready Team Training Advisory committee and contributing individuals:
Art Bloom
Rob Blake
Elaine Brainerd
Vickie Church
Holly Coleman
Cheryl Connelly
Alicia Fry
Nancy Gathany
David Goldman
Bob Harrington
Ernest Julian
Jimmy Lui
George Nakamura
Charles Otto
J. Douglas Park
Kenneth Pearson
Lawrence Pong
Fred Ramsey
Cindy Roberts
Michele Samarya-Timm
Mark Schmidt
Rebecca Shapack
Susan Shiflett
Julia Smith
Past NEHA President; Portland, Oregon
DeKalb County Board of Health; Atlanta, Georgia
American Nurses Foundation; Washington, D.C
San Diego Department of Environmental Health; San Diego, CA
Chatham County Health Department; Apex, NC
National Association of County and City Health Officials
Centers for Disease Control and Prevention; Atlanta, GA
United States Department of Agriculture; Washington, D.C.
Casper/Natrona County Health Department; Casper, WY
State of Rhode Island Department of Health; Providence, RI
Food Safety Web Specialists; Washington, D.C
Contra Costa Health Services; Concord, CA
Food and Drug Administration; College Park, MD
Knox County Health Department; Knoxville, TN
San Francisco Environmental Health; San Francisco, CA
United States Department of Agriculture; Albany, NY
Food Safety Web Specialists; Washington, D.C.
Franklin Township Health Department; Somerset, NJ
Michigan Department of Community Health; Lansing, MI
National Association of County and City Health Officials
Michigan Department of Community Health; Lansing, MI
For additional information on this course, please contact:
National Environmental Health Association
720 S. Colorado Blvd. Suite 1000-N
Denver, CO 80246
Phone: (303) 756-9090
FAX: (303) 691-9490
www.neha.org
© National Environmental Health Association August 2003
This educational material is the sole and exclusive property of the National Environmental Health
Association. Any use, copying or reproduction of this material without written permission from
NEHA is forbidden
Epi-Ready Team Training
Foodborne Illness Response Strategies
Purpose
The goal of this training is for public health professionals and other involved
personnel to rapidly identify and investigate a foodborne disease outbreak to
allow for implementation of control measures to reduce the incidence of
foodborne illness.
Overall Objectives
At the end of this training, the participant will be able to:
1.
Describe the process of gathering data through passive surveillance.
2.
List criteria for beginning an outbreak investigation.
3.
Describe the purpose of an environmental assessment.
4.
Use epidemiological study data to identify outbreak cause(s).
5.
List four steps for submitting samples to a laboratory for testing.
6.
Document and report the results of an outbreak investigation.
7.
Evaluate the similarities between incidental and intentional foodborne
illness. (e.g. Bioterrorism link)
Epi-Ready
Foodborne Illness Response Strategies
Special thanks to CDC’s Food Safety Office,
particularly Dr. Art Liang, Dr. Don Sharp, and
Richard Skibicki, as well as the Epi-Ready Advisory
Committee and others who collaboratively gave
unselfishly of their time and advice.
© National Environmental Health Association 2005
Epi-Ready Foodborne Illness Response Strategies
2
ACKNOWLEDGEMENTS
Individuals who served on the F.I.R.ST. workgroup:
Sally Bidol
Tom Buss
Joann Clinchoc
Sonja Hrabowy
Whitney Mauer
Cindy Overkamp
Doug Park
Susan Shiflett
John Tilden
Michigan Department of Community Health
Grand Traverse County Health Department
City of Detroit Health Department
Kent County Health Department
Kalamazoo County Human Services Dept.
Michigan Department of Agriculture
Michigan Department of Agriculture
3
INTRODUCTION
1
Identify roles, responsibilities, and legal
requirements
Promote teamwork and consistency
Answer commonly asked questions
through
Workbook
Presentations
Question and answer sessions
4
Surveillance
Prevention
Measures
Epidemiologic
Investigation
Applied
Research
Source: Centers for Disease Control and
Prevention
5
76 million illnesses
323,000 hospitalizations
5,000 deaths
First comprehensive estimates
by CDC since 1987
Used for new cost estimates,
risk-assessment, model for
other disease estimates
Source: Centers for Disease Control and Prevention
6
INTRODUCTION
2
Bacterial
Bacillus
Brucella
Campylobacter
Clostridium
Escherichia
enterohemorrhagic
enterotoxigenic
Listeria
Salmonella
Shigella
Staphylococcus
Streptococcus
Vibrio
Parasitic
Cryptosporidium
Cyclospora
Giardia
Toxoplasma
Trichinella
Viral
Norovirus
Rotavirus
Astrovirus
Hepatitis A
Chemical
Scombrotoxin
Ciguatoxin
Mushroom poisoning
Heavy metals
7
Perceived Etiology of Foodborne
Illness among Public Health
Personnel
The Tennessee Survey
8
Tennessee Survey
Percentage of
respondents
listing it among
top 3 causes
Est. % of
foodborne illness
in USA caused by
pathogen
Pathogen
Campylobacter
Clostridium perfringens
Escherichia coli
Giardia lamblia
Hepatitis A virus
Listeria
Norwalk-like virus
Salmonella
Shigella
Staphylococcus
Streptococcus
Viruses
Source: Jones, T.F., Gerber, D.E. Dispatches “Perceived Etiology of Foodborne Illness
among Public Health Personnel” http://www.cdc.gov/ncidod/eid/vol7no5/pdf/jones.pdf
9
INTRODUCTION
3
Agent
• Recently recognized pathogens
• New foodborne modes of transmission
Host
Environment
• Increasing elderly,
immunocompromised
• New eating habits
• Increasing immigration,
international travel
• Globalization of food supply
• Centralization of food
processing, large producers
Number of Patients
12
11
10
9
8
7
6
5
4
3
2
1
0
Fatal
Non-fatal
Recall
Usual listerosis
incubation period
Source: Centers for Disease
Control and Prevention
Plant
Construction
6/27
8/2
10
9/6
10/11
11/15
Date
12/20
1/24
2/27
4/3
11
Source: International Association for Food Protection
12
INTRODUCTION
4
Decide to
Investigate?
Passive
Surveillance
YES
Outbreak
Determination
Confirm if
Outbreak
Occurred?
NO
YES
Outbreak
Investigation
Laboratory
Guidance
NO
Concluding
Actions
13
14
L
y
or
at
r
o
ab
em
id
Ep
io
gy
lo
v
En
nm
iro
t
en
15
INTRODUCTION
5
At the end of this module, the participant will be able to:
1. Define “active” and “passive” surveillance systems.
2. Identify potential sources of surveillance data.
3. Name components of a successful surveillance system.
4. Identify reports used to document foodborne illness.
5. Refer complaints to appropriate individual and/or agency.
6. Describe the elements included on an ongoing log of foodborne
illness complaints.
7. Define outbreak.
8. List important items of passive surveillance data to review.
9. List reasons whether or not to investigate complaints further.
Notification
of Illness
Obvious
outbreaks (go to
Module 2 or 3)
Refer complaint
to responsible
person
Log complaint
Review log and
other data for
related cases
NO
Prepare
Investigation (go to
Module 2 ,3, or 4)
YES
Decide
whether to
investigate
further
*Both laboratory confirmed cases and unconfirmed reports (illness complaints)
Illness
Have
surveillance
system in place
Module 1:
Passive Surveillance*
Task List
Illness

Review symptomology and onset times for common foodborne illnesses.

Utilize recognized information resources for supplemental information.
o Control of Communicable Diseases Manual
o IAFP documents
o www.cdc.gov Health Topics A to Z
o FDA Bad Bug Book
o MMWR
Notification of Illness

Use approved forms to document initial reports and gather appropriate information.

Each section on the form has a purpose.

For obvious outbreaks, record key information on line list and go to Module 2 or 3.

Encourage symptomatic clients to submit appropriate clinical specimens.

Notify state agencies and other local jurisdictions.
Obvious Outbreaks

Document all outbreak reports in a foodborne illness complaint log (or equivalent
electronic data storage system).

Promptly initiate appropriate steps outlined in Modules 2, 3 and/or 4.

Identify the information that will need to be gathered during the investigation.

Consult with state agencies as needed.
Refer To Responsible Person(s) or Agency

Refer complaints to the agency with regulatory authority over that facility for
collaboration and follow up.

Follow-up complaints involving facilities under your jurisdiction.

Notify communicable disease staff of outbreaks and reported incidents involving
laboratory-confirmed infections.

Clearly document referred incidents and what follow up actions were taken.
Log Complaint

Assign a unique sequential number to each complaint or case investigation.

Instruct staff on how to systematically enter data into log.

Transfer key information from input forms to log.

Establish a retention schedule for surveillance records.
Review Log and Other Data for Related Cases

Establish a written procedure for reviewing surveillance data.

Check baseline data to determine expected levels of health events.
Decide Whether to Investigate Further

Review the foodborne outbreak definitions. (There needs to be a clear message
here.)

Review surveillance information to identify what is known and what pieces of
information are missing.
Review published literature about pathogen (known or suspected) involved.
Epi-Ready
Passive Surveillance
Passive
Surveillance
Decide to
Investigate?
NO
YES
Outbreak
Determination
Confirm if
Outbreak
Occurred?
YES
Outbreak &
Epidemiologic
Investigation
Laboratory
Guidance
NO
Concluding
Actions
2
Module Learning Objectives

Define “active” and “passive” surveillance
systems.
Identify potential sources of surveillance
data.
Name components of a successful
surveillance system.
Identify forms used to document foodborne
illness.
Refer complaints to appropriate individual
and/or agency.
3
MODULE 1: PASSIVE SURVEILLANCE
1
(cont.)
Describe the elements included on an
ongoing log of foodborne illness
complaints.
Define outbreak.
List important items of passive
surveillance data to review.
List reasons whether or not to investigate
complaints further.
4
PASSIVE
SURVEILLANCE *
No
Have surveillance
system in place
Illness
Notification
of Illness
Refer complaint
to responsible
person
Log
complaint
Review log
and other
data for
related cases
Obvious
outbreaks
Decide
whether to
investigate
further
Yes
Prepare
Investigation
* Both laboratory confirmed cases and unconfirmed reports (illness complaints)
5
Two Types of Surveillance
Active surveillance
Passive surveillance
6
2
Active Surveillance
Regular periodic collection of case
reports from health care providers or
facilities
Advantage: data is more accurate than
in other types of surveillance
Disadvantage: expensive and time
consuming
7
Information provided to the health agency
without an initiating action by the
agency
Required routine reporting by physicians and
laboratories
Reports from concerned citizens
Advantage: less expensive and troublesome
to operate
Disadvantage: likely to underestimate the
presence of disease
8
The Surveillance Pyramid
Reported to health dept
state
CDC
Culture-confirmed case
Lab tests for organism
Specimen obtained
Person seeks care
Person becomes ill
Population
exposures
9
3
Sources of Foodborne Disease Data
Foodborne
Outbreak
Surveillance
System
Epidemic
Investigations
Laboratorybased
Surveillance
Complaint
Investigations
10
Infectious Disease Surveillance
State public health codes require
physicians and laboratories to report
certain infectious diseases to public
health authorities
States report nationally-notifiable
diseases to CDC
• MMWR Recommendations & Reports,
1997; 46(RR-10)
11
Foodborne Classifications of
calls to EH at local level
Family
Alerts
Foodborne
Outbreaks
Isolated
Consumer
Complaints
Different streams of data – local to federal
12
4
Foodborne Diseases Active
Surveillance Network (FoodNet)
[15.2% of the U.S. population]
Year
Pop’n*
1996
14.3
1997
16.1
1998
20.7
1999
25.9
2000
30.5
2001
34.9
2002
38.0
2003
41.5
2004
43.3
2005
44.1
2006
44.9
* in millions
13
Incidence* of Selected Foodborne
Diseases, United States
Healthy
People
Objectives
FoodNet Data
Pathogen
1996
1998
2000
2002
2004
2006
2010
Campylobacter
23.5
21.7
15.4
13.3
12.9
12.7
12.3
Salmonella
14.5
12.4
14.2
16.2
14.7
14.8
6.8
E. Coli
O157:H7
2.4
2.8
2.0
1.7
0.9
1.3
1.0
Listeria
0.5
0.6
0.34
0.26
0.27
0.31
0.25
* per 100,000 population/year
** estimated, baseline for 2000 objectives
14
15
5
Pathogens Subtyped by PulseNet,
United States
1998
1999
2000
2002
E. coli O157:H7
1996 1997
X
X
X
X
X
X
Salmonella
X
X
X
X
X
X
Listeria
X
X
X
Shigella
X
X
X
X
Campylobacter
16
Listeriosis Outbreaks in the
United States 1979-2000
PulseNet
Year
2000
2000
1999
1999
1998
1994
1989
1985
1983
1979
Vehicle
Deli meat
Cheese
Pate
Imported cheese
Hot dogs
Milk
Shrimp
Cheese
Milk
Produce
State
(10)
NC
(3)
(4)
(22)
IL
CT
CA
MA
MA
17
Number/100,000 pop.
Salmonella Enteritidis Incidence
by Region, United States, 1970-99
12
10
8
6
4
2
0
1970 72 74 76 78 80 82 84 86 88 90 92 94 96 98
Year
Total
New England
Mid Atlantic
Pacific
Other
Mountain
18
6
Surveillance System in Place
External partners
Teams
•
•
•
•
•
•
• Epi
• Environmental health
• Communicable disease
nursing
• Lab
• Health educator
Hospitals
Clinics
Physicians
Fire
Police
Industry
19
Networking
Share information with
other local health
departments in region
Provide up-to-date list
of key contacts in local
area
Maintain
an information
flow
20
Local Health Dept. Preparation
Define roles and responsibilities
Have needed supplies on hand
Procedures for sharing information
(internally and externally)
Training plan
Periodic meetings
21
7
Obvious Outbreaks
Document all illness reports in a
foodborne illness complaint log
Initiate appropriate steps during
outbreak investigation
Identify information needs
Notify and consult with appropriate
departments (i.e. up the chain of
command and horizontally to everyone
that may need to know)
22
Notification of Illness
Symptomatic clients
submit clinical specimens
Obvious outbreaks
record on the line list
Use approved forms to
document initial reports
23
IAFP Forms A, C1 and C2
24
8
Refer to Responsible Person
or Agency
Refer complaints to agency with
regulatory authority for collaboration
Follow-up complaints under your
jurisdiction
Notify communicable disease staff of
confirmed infections
Clearly document referred incidents
25
Log Complaint
Assign unique sequential number to each
complaint
Systematically enter data into log
Transfer key information from input forms to log
Establish retention schedule for surveillance
records
26
Review Log and Other Data
for Related Cases
Who’s in charge?
Establish written
procedure for reviewing
surveillance data
Check expected levels
of health events
27
9
Outbreak ??
Expected?
Norm?
Comparisons?
28
Outbreak ??
Actionable events are defined locally.
Each jurisdiction has to determine
whether or not to investigate.
CDC and other Federal Agencies have
listed the following general definitions as
guidance.
29
Foodborne Illness Outbreak Definition
CDC and IAFP Definition
An outbreak is an incident in which two or more
persons have the same disease, have similar
clinical features, or have the same pathogen thus meeting the case definition - and there is a
time, place or person association among these
persons.
A foodborne outbreak is one that is traceable
to ingestion of a contaminated food.
30
10
Food Emergency Definition
(exception to the Outbreak Definition)
A single case of suspected botulism,
mushroom poisoning, ciguatera or
paralytic shellfish poisoning or other rare
disease, or a case of a disease that can be
definitely related to ingestion of a food, can
be considered an incident of foodborne
illness and warrants further investigation.
31
Determine Whether to
Investigate Further
Increase in the number
of reports over expected
Possible epi association
(person, place, and
time)
Possible laboratory
linkage
32
How to Investigate Further
Review surveillance information
Review foodborne outbreak definitions
Review published literature about
pathogen (known or suspected) involved
33
11
Summary
YES
Passive
Surveillance
Decide to
Investigate?
N
O
YES
Outbreak
Determination
Confirm if
Outbreak
Occurred?
Outbreak &
Epidemiologic
Investigation
Laboratory
Guidance
N
O
Role
Epi.
Receives data from established passive surveillance
systems, reviews data, determines the need to investigate
further.
Lab.
Contributes final reports of testing to established passive
surveillance systems.
Environ.
Concluding
Actions
Receives data from established passive surveillance
systems, reviews data, helps determine the need to
investigate further.
34
Log Book Group Exercise
Which of these logged reports would you
use your limited resources to investigate
further? Why?
35
12
Module 2: Outbreak Determination
1. List steps needed to prepare for an investigation.
2. Describe actions needed to verify the diagnosis.
3. Identify means for searching for additional cases.
4. List three phases of interviewing.
5. List steps for obtaining a case history.
6. Describe methods for overcoming barriers to interviewing.
7. Describe methods to ensure consistency of interview data.
8. Identify epidemiologic associations.
9. Determine if an outbreak has occurred.
Prepare
Investigtion
Take steps to
verify diagnosis
Get case history
Obtain clinical
specimens
Collect food
samples
Develop initial
case definition
Module 2:
Outbreak Determination
Make
epidemiologic
(time, place,
person)
associations
Outbreak
Investigation (go to
Module 3, 4, 5)
YES
Determine
whether an
outbreak
occurred
NO
Generate
termination report
Module 2 Outbreak Determination
Task List
Prepare Investigation

Share surveillance information with team members and other designated staff.

Get appropriate approval from supervisors for planned activities.

Gather supplies, equipment, and resources needed to carry out case finding (e.g.,
forms, equipment, personnel, media spokesperson).

Review scientific information regarding known or suspected agents.

Notify state agencies and local health departments that may be impacted.
Take Steps to Verify Diagnosis

Review preliminary information to verify accuracy.

Identify what further laboratory analysis or information gathering is needed.

Refer to appropriate health care provider or agency with jurisdictional authority.
Get Case Histories

Establish rapport with the individuals being interviewed.

Determine if food samples or clinical specimens are available for testing.

Identify if samples will be collected, tested, and who will collect the samples.

Fully complete all forms.

Ask if individuals have unanswered questions or additional information to share.

Thank them for their cooperation.

Ensure completed questionnaires, environmental surveys, and other investigation
data are turned in to designated person(s).

Review for completeness and data quality.

Take actions, as needed, to gather missing or incomplete data.
Collect Food Samples

Take steps to ensure samples are not lost or destroyed.

Collect samples using aseptic technique.

Hold samples under conditions that maximize usefulness.

Determine which tests to request through consultation with laboratory staff.

Complete chain of custody, laboratory analysis request and related forms.
Obtain Clinical Specimens

Ask if the individual is experiencing symptoms or has submitted a stool specimen.

Collect specimens following guidance provided by appropriate laboratory.

Determine which tests to request.

Complete the required paperwork for each specimen.

Contact laboratory staff to arrange for testing before sending samples.
Search for Additional Cases

Activate surveillance network.

Inquire about other confirmed or unconfirmed illnesses during patient interview.
Make Epidemiologic Associations (Person, Place, Time)

Organize key information from cases using a line list or similar document.

Summarize data by person, place and time.

Systematically review all information and develop initial hypothesis.
Determine Whether an Outbreak Occurred

Review definitions of a foodborne illness outbreak.

Review EH and CD logs for potentially associated cases.

Designated LHD staff should determine if an outbreak has occurred.

If an outbreak has not occurred, document your conclusions -“Termination report”.

Document why a final report was not written.
If a foodborne illness outbreak has occurred:

Assemble foodborne outbreak team with representatives with known roles and
responsibilities in the following areas:
•
•
•
•
•
•
Overall team leader
Administration
Environmental
Communicable Disease / Epidemiology
Laboratory
Media and Public Communications

Establish schedule for team meetings.

Review all known information with team members.

Take immediate actions needed to prevent additional cases.

Monitor to determine effectiveness of actions.

Proceed to Module 3, 4 and 5 for outbreak investigation.
Epi-Ready
Passive
Surveillance
Decide to
Investigate?
YES
Outbreak
Determination
NO
Confirm if
Outbreak
Occurred?
YES
Outbreak &
Epidemiologic
Investigation
Laboratory
Guidance
NO
Concluding
Actions
2

List steps needed to prepare for an
investigation
Describe actions needed to verify the
diagnosis
Identify means for searching for
additional cases
List three phases of interviewing
List steps for obtaining a case history
3
MODULE 2: OUTBREAK DETERMINATION
1
(cont.)
Describe methods for overcoming
barriers to interviewing
Describe methods to ensure consistency
of interview data
Identify epidemiologic associations
Determine if an outbreak has occurred

4
Flow Diagram
Generate
termination
report
Collect food
samples
Prepare
Investigation
Take steps to
verify
diagnosis
Obtain clinical
specimens
Develop initial
case definition
Make
epidemiologic
(time, place,
person)
associations
Determine
whether an
outbreak
occurred
Get case
history
Outbreak
Investigation
5

Identify outbreak investigation team
Share surveillance information
Get appropriate supervisor’s approval
Gather supplies and equipment
Review scientific information
Notify state and local departments
• e.g. local
state
federal
Photo courtesy of King County, WA
6
2
When To Activate The Team?
Risks and benefits of involving others
early on
• “The sky is falling!” syndrome
• The stealth investigator
Begin with the end in mind - what
information needs to be gathered?
7
Goal: each one doing
the job they know to do
Prior planning
• Cannot address every
situation
• Reduces the number of
issues needing to be
discussed during the
crisis
8
Next Steps
Verify diagnosis
Search for
additional cases
Determine if cases
are associated
9
3
Actions to Verify Diagnosis
Review preliminary
information
Get case history
Collect food samples
Obtain clinical specimens
Appropriate referral to
medical care facilities
10
Photo courtesy of CDC
Activate surveillance
network(s)
• Health Care Facilities
• Laboratories
• Exposure Location, if known
Inquire during interview
• confirmed
• unconfirmed
11
Get Case History
Identify relationship(s)
with other cases
Ask if still sick
Get at least a 72 hour
meal history and list of
environmental exposures
Don’t use forms designed
for isolated cases to
investigate potential
outbreaks
12
4
Obtaining Demographic, Exposure,
and Disease Information
All types of investigations require
accurate and complete data!
Demographic information (age, gender,
address, other identifying data)
Exposure history (food consumption &
environmental exposures)
Disease information (symptoms/signs)
A good interview is a MUST!!!
13
Two Ways to Obtain Information
1.) Written questionnaires
2.) Interviews
- in-person
- telephone
14
Written Questionnaires
Can be an alternative to in-person or
telephone interviews
Limitations
• Can have poor response rates
• Respondent can misinterpret or fail to
understand questions
Advantage
• Can substantially reduce resources devoted
to gathering information, esp. with large
outbreaks
15
5
Outbreak Investigation
Interviewing Skills
16
Interviewing Goals
Be consistent in interviews
Do your homework to minimize
repeat contacts
Target questions to greatest
degree possible
17
Three Phases of Interviewing
Before
During
After
18
6
Before Interviewing
Identify objectives
• To determine source of illnesses and
means of transmission
• Minimize repeat interviews
19
Before Interviewing (cont.)
Identify and prepare interviewers
• Assign interviewers; training for all
• Arrange work schedules (24/7 work)
Assess workload
• Number of interviews needed
• Types of individuals to interview
Select forms to use
20
Interviewing Forms
Agree on format
and content
Review new forms
with all interviewers
Pilot test new forms
whenever possible
21
7
Know What You Are After
Two purposes:
1.) Generate hypothesis
2.) Test hypothesis
22
Generic Interviewing Forms
Used for small outbreaks or early in
investigation
Use same forms - consistency
23
Open Ended Questions
Data gathering
Hypothesis generating
Typically used for initial interview
Drawback - difficult to analyze
statistically
Time consuming

24
8
Customized Interviewing Forms
Gather specific info after have basic
initial info
Questions unbiased
Order and format of questions can
affect answers
25
Closed Ended Questions
Gather specific information
Can be restrictive and leading
Can target specific topics
Yes______
No_______
Unknown______
26
Closed Ended Questions (cont.)
No biased questions
No “double barrel” questions
Example: “Did you cook and
then promptly cool the ground
beef”?
27
9
Before
During
After
28
During Interviews
Establish rapport
Identify self, organization, and reason
for investigation
• Need cooperation to identify source and
prevent others from getting sick
• Be empathetic
Start with easy questions
• “Your name/ address/ occupation?”
29
During Interviews (cont.)
Share at the beginning that during the
course of the investigation
• Multiple contacts may be needed
• Focus of questions may change
30
10
When they cannot remember
meals:
?
Ask about food preferences
Can rule in / out some foods
Identify key days and dates to jog
memory (use calendar)
Review receipts and/or checkbook
31
Buffets - food items
generally not labeled
• Need to clearly
describe each food
People remember
better what they
ordered from a menu
32
Always provide respondents with an
“Other Food” option
• Identify “new” previously unidentified food
• Double check master food list
Other Food ________________
33
11
Ask questions as written on form
Review form before ending interview
Ask if individuals have
• Unanswered questions
• Additional information
Thank them
34
Identifying and Overcoming
Communication Barriers
Cultural diversity
Communication styles
• Identify communication style of interviewee
• Adjust your style to match
Last meal bias
• Take multi-day food history
35
Identifying and Overcoming
Communication Barriers (cont.)
Irate consumer
• Be sensitive, adjust communication style
Information often missed
• Identify facility locations, extent of exposure, timeline
and specific signs and symptoms
• Check for food or clinical samples
• Consider non-foodborne transmission
Commercial food products
• Obtain specific dates, locations and product
descriptions
36
12
Consider Human Dynamics
Anticipate communication barriers
• Demographic or cultural factors
• Defensiveness
Identify appropriate sites and times
for interviews
• Privacy
• Free from distractions
37
Diversity
38
Assess Communication Styles
Action - bottom line / “Just
the facts”
Feeling - empathetic
Creative - need to see the
big picture
Thinking - want all the
details
39
13
The Last Meal Bias
40
The Irate Consumer
41
Information Often Missed
Location of facility (be specific)
Example:
• “Chain X store in Anytown, USA”
• “Chain X store on corner of Main and Fourth
in Anytown, USA”
Anytown
X
245 Main St
Fourth
• “Chain X store located at 245 Main Street in
Anytown, USA”
Main
42
14
(cont.)
Extent of exposure (who else ate the
food)
• Names and contact information of other
persons at event
• How much did they eat?
43
(cont.)
Timeline information
• Purchase date/time
• Consumption date/time
• Symptom onset date/time
(for incubation period)
Specific signs and symptoms
• Especially important if no laboratory
confirmation
44
(cont.)
Check if food or
clinical samples still
available
Information needed to
assess potential for
non-foodborne routes
of transmission
45
15
Non-Foodborne Routes of
Disease Transmission
46
The Real Cause of Waterborne
E. coli Outbreaks
47
Outbreaks Involving
Commercial Food Products
Purchase dates and
locations
Product
descriptions (labels,
lot codes)
48
16
Read the Label: All “Hamburger”
Was Not Created Equal
49
Restaurants
Be as specific
as possible
How many
“combination
chicken platters”
can there be?
50
Before
During
After
51
17
After the Interview
Give questionnaires to one key person
• Epidemiologist, nurse, clerk, sanitarian
• Goal: early identification of
inconsistencies
Enter information into database ASAP
Keep track of
• Who has been interviewed
• Who is interviewing
52
Steps to Ensuring Consistent
Data
Before the interview
During the interview
After the interview
53
Identify Epidemiologic
Associations
Summarize Initial Data
Descriptive Epidemiology – describes
patterns of disease
• Person
• Place
• Time
Used to generate hypothesis for further
study
54
18
Person: Frequency Tables
Distribution of age among all respondents
AGE
|
Freq
Percent
Cum.
-------+-------------------------------0-9
|
4
10.5%
10.5%
10-19
|
5
13.2%
23.7%
20-39
|
12
31.6%
55.3%
40-59
|
10
26.3%
81.6%
60+
|
7
18.4%
100.0%
-------+-------------------------------Total
38
100%
55
Place: Spot Maps
• 10 people who
died lived closer to
another pump
• 5 people who died
always sent to pump
in Broad Street
were children
attending school
near the Broad
Street pump
Dr. John Snow, September 1854
56
Time: Epidemic Curve
57
19
Develop an Initial Case
Definition
Use descriptive information
to develop an initial case
definition
58
Data to Consider in Developing
the Initial Case Definition
Person, place and time
Laboratory data
Environmental data
59
60
20
Summary
YES
Passive
Surveillance
Decide to
Investigate?
YES
Outbreak
Determination
N
O
Role
Outbreak &
Epidemiologic
Investigation
Confirm if
Outbreak
Occurred?
Laboratory
Guidance
N
O
Concluding
Actions
Epi.
Verifies diagnosis and determines whether cases are
associated; searches for additional cases and conducts
interviews; determines whether an outbreak has occurred.
Lab.
Helps verify diagnosis and determine whether cases are
associated.
Environ.
Helps verify diagnosis and determine whether cases are
associated; helps search for additional cases; conducts
facility interviews and collects samples; can conduct case
interviews
61
Interview Exercise
College Student Interview
62
21
Module 2 Interviewing Group Exercise:
A Potential Sorority/ Fraternity Outbreak?
Background for the INTERVIEWER:
It is Monday morning. You receive a message that a student who attends the local
University in your jurisdiction had called with a foodborne complaint. She/he reports
that she/he attended a local pizzeria with her/his sorority/fraternity sisters/ brothers
Saturday night. Several hours later they developed nausea, vomiting, and diarrhea that
lasted throughout the night. Call the student back to collect a case history. You are
free to use any tools or interviewing aides that you normally would use to interview this
person. Copies of forms are in student handouts.
A Potential Sorority/ Fraternity Outbreak?
Background for the INTERVIEWEE:
It is Monday morning. You call and leave a message with the local health department
that you, a student who attends the local University, developed diarrhea, nausea and
vomiting late Saturday night. You attended a local pizzeria for dinner with your sorority
sisters (or fraternity brothers) one of which is also your roommate. You are absolutely
positive that the pizza eaten at the pizzeria is what made you sick.
After dinner at the pizzeria, you and your sisters/ brothers went to the local bar and
consumed numerous alcoholic beverages. Both you and your roommate developed
nausea, vomiting (which is rather common for you) and diarrhea sometime between 2
and 4 am early Sunday morning. You also developed fever and chills. You are still
feeling sick, which is different than your typical weekend nausea and vomiting.
A total of seven sisters/ brothers went to the pizzeria (including you). There is a total of
four people ill including you and your roommate. Two more sisters/ brothers became ill
last night.
You have not gone and will not go to the doctor, especially to provide a stool specimen
– that’s gross. Your roommate did go to the University clinic. Another sorority sister/
brother is sick and is thinking of going to the clinic. You can be talked into submitting a
stool specimen.
You do not want to provide your sisters’/ brothers’ names to the health department. You
would be willing to contact your sister/ brothers and have them contact the LHD.
All of the sisters/ brothers live on-campus in three different dorms. You have heard that
some other people who live in your dorm are sick with the same symptoms.
You do not want to provide a 3-day meal history because this is extraneous information
and you aren’t really motivated initially to try and remember. You feel that identifying
the pizzeria (which also provided bad service) is all that the LHD needs to know. If the
interviewer is convincing (cut them some slack) you can be convinced to share that you
don’t eat breakfasts (who gets up in time to eat breakfast?), both you and your
roommate like to eat lunch at the on-campus cafeteria (usually at the one campus
cafeteria deli bar and that dinners that week were at various bars around town.
You feel that the LHD nurse is incompetent and you are too busy to answer questions
that are unimportant because you already identified what made you ill.
Elaborate on this scenario as needed to keep the interview flowing. Feel free to be
difficult so that the interviewer can be challenged.
Interview Evaluation
Were these objectives met?
Establish Rapport
Did the interviewer identify themselves and explain why they were calling?

Did they explain why the questions they were asking were important?

Did the interviewer address last meal bias and explain that pathogens may take
days to cause illness?
Purposeful Directed Information Gathering
Was the interview structured and “flowing”?

Did the interviewer use a data collection form?

Did the interviewer explain that they may need to re-contact the case and did
they ask when a good time to call back is?
Verify Diagnosis
Did the interviewer verify the diagnosis by collecting data about symptoms, onset
time, medical care etc.?

Did the interviewer refer the student for collection of stool specimens?

Did the interviewer ask if leftovers were available?

Did the interviewer collect a 3-day meal history?
Did the interviewer ask about additional cases?

Did the interviewer ask about other people who attended the events who were
not ill?
Look for Person-Place-Time Associations
Were person, place, and time association linkages looked for?
What else would you want to ask?
1. Describe/distinguish the difference between environmental
assessment (which would include interview and verification),
plan review / HACCP inspection, and routine inspection.
2. Describe methods for overcoming barriers to on-site data
gathering.
3. List the contributing factors typically associated with foodborne
illness.
4. Describe the necessary steps to be covered in the
environmental assessment (including steps in pre-visit planning
and on-site data gathering).
5. Identify the importance of Contamination, Survival, and
Proliferation (CSP).
6. Describe the importance of maintaining key information for the
final report.
Task List
Planning Before Visiting the Site

Determine scope and objective(s) of the site visit.

Review available outbreak information (epidemiologic and laboratory findings).

Review available facility information

Review applicable sections of IAFP manual.

Review principles of effective interviewing

Gather needed resources
On-site Data Gathering

Meet with the facility manager(s) and consult with facility staff.

Observe applicable food operations

Review available records

Collect environmental and/or food samples

Draw/revise initial flow chart and diagram

Implement actions (as needed) to stop the outbreak and/or prevent future
reoccurrence.
Hazard Analysis

Identify the on-site factors that contributed to the outbreak in the following areas:
• Contamination
• Survival
• Proliferation

Implement actions (as needed) to stop the outbreak and/or prevent future
reoccurrence.

Document your findings and immediately share with investigation team members and
facility managers (as appropriate).
Assemble
Team
Initial
Plan
Initial Case
Definition
Outbreak Investigation Flow Diagram
Yes
STEP 1: Confirm Outbreak
Determine
if Outbreak
Occurred
Make
Notifications
Initial
Hypothesis
Refine
Hypothesis
Outbreak
Concluding
Actions
(Go to Mod. 4)
Analyze
Data &
Interpret
Results
Epidemiologic
Investigation
Refine
Case
Definition
STEP 2: Hypothesis Testing and Analytic Investigation
Assign
Tasks
Laboratory
Sample
Collection
Environmental
Assessment
Repeat as
Necessary
Epi-Ready
Environmental Assessment
YES
Decide to
Investigate?
Passive
Surveillance
YES
Confirm if
Outbreak
Occurred?
Outbreak
Determination
NO
Outbreak
Investigation/
Environmental
Assessment
Laboratory
Guidance
NO
Concluding
Actions
2
STEP 1: Confirm Outbreak
Determine
if Outbreak
Occurred
Yes
Assemble
Team
Initial
Plan
Initial Case
Definition
Make
Notifications
Initial
Hypothesis
3
MODULE 3: ENVIRONMENTAL ASSESSMENT
1
STEP 2: Hypothesis Testing and Analytic Investigation
Epidemiologic
Investigation
Assign
Tasks
Laboratory
Sample
Collection
Refine
Case
Definition
Refine
Hypothesis
Analyze
Data &
Interpret
Results
Outbreak
Concluding
Actions
Environmental
Assessment
Repeat as
Necessary
4

Identify food establishments as dynamic
systems

Describe the difference between plan review,
risk-based inspection, and environmental
assessments

Identify the contributing factor categories
typically associated with foodborne illness
•
•
•
Contamination
Survival
Proliferation
5
(cont.)

Describe methods for overcoming barriers
to on-site data gathering

Describe basic steps of environmental
assessments

Describe the importance of a well
documented final report
6
2
Sources of
Foodborne Illness Outbreaks
are Varied

Restaurants
Grocery store delis
Church potluck suppers
Summer camps
Food processors
Farms
Trucks
7
Dynamic Nature
of Food Facilities
Food Operations are NOT static
Time of Day will be Significant
Focus on Processes and Food Flows
Production Schedules vs. Prepare to Order
Assessing Risk Factors Requires Patience
8
Food Establishments
Are Systems
Input: Energy or raw material that enters the
system
Processes: The way input is transformed
Output: The product or service that results from
the process
Feedback: Information that can be used to
evaluate and monitor the system
SOURCE: EHS-Net
9
3
Food Service Establishment
as a System
Hold
Assemble
Reheat
Serve
Customer
Health
Internal System Elements
People
Final Food
Item
Equipment
Cool
Customer
Satisfaction
Profit
Process
Foods
External Feedback to System
Economics
Ingredients
Cook
Receive
Organisms
Chemicals
Prep
Store
& = Inputs
& = Processes
& = Outputs
& = Feedback
SOURCE: EHS-Net
10
Partial List of Known Causes
of Foodborne Illness
Bacterial
Bacillus
Brucella
Campylobacter
Clostridium
Escherichia
enterohemorrhagic
enterotoxigenic
Listeria
Salmonella
Shigella
Staphylococcus
Streptococcus
Vibrio
Parasitic
Cryptosporidium
Cyclospora
Giardia
Toxoplasma
Trichinella
Viral
Norovirus
Rotavirus
Astrovirus
Hepatitis A
Chemical
Scombrotoxin
Ciguatoxin
Mushroom poisoning
Heavy metals
11
Contributing Factors Associated
with Foodborne Illness Outbreaks

Improper holding temperatures
Inadequate cooking
Contaminated equipment
Unsafe source
Poor personal hygiene
Cross contamination
Photos courtesy of Larry Pong
12
4
Food Safety Management
Systems:
The Prerequisites
Employee Health
Personal Hygiene Program
Time Temperature Management
Cleaning and Sanitizing of Food Contact
Surfaces
Cross Contamination Prevention
Date Marking

13
Every technical
food safety issue
will ultimately become a
human resource
issue
14
Process 1: Food Preparation
with No Cook Step
Receiving
Example:
Store
Prepare
Hold
Serve
Sandwiches w/ RTE Fillings
Canned Tuna
Canned Chicken
Lunch Meat
etc.
15
5
Priorities Associated with Process #1
No Cook Step
Cold Holding or Time Alone as a Control
Food Source (Shellfish; Sashimi)
Receiving Temperatures
(Tuna; Species of Finfish)
Freezing to Destroy Parasites (Fish for Sushi)
16
Process 2: Preparation for
Same Day Service
Receive
Store
Prepare
Cook
Hold
Serve
Example: Hamburgers
17
Same Day Service
Cooking
Hot Holding
Time Alone as a Microbial Growth Barrier
18
6
Process 3: Complex Food
Preparation
Receive
Reheat
Store
Prepare
Hot Hold
Cook
Cool
Serve
Example: Hot Catered Meal
19
Complex Food Prep

Cooking
Hot Holding
Time Alone as a Microbial Growth Barrier
Cooling
Reheating
20
Danger Zone Diagram
21
7
Types of Environmental Activities
Plan Review / HACCP
• Focuses on FUTURE operations
Routine Regulatory Inspection
• Focuses on PRESENT operations
Environmental Assessment / Food Prep Review
• Focuses on PAST operation/event
22
Plan Review & HACCP
Evaluate plans and procedures
Identify potential problems before they lead to
foodborne illness
Identify control points to prevent foodborne
illness
23
Routine Inspection
Emphasis has evolved
Old days - legal
compliance checklist
mentality
Currently recommend
risk-based inspections to
identify cause of
foodborne illness
24
8
Conducting Risk-based
Inspections
I.
II.
Inspection focus
Identify food process categories
present
III. Establish priorities
IV. Determine risk factors in process flows
V. Assess active managerial control of
risk factors in process flows
25
(Food Preparation Review)
Definition: A systematic evaluation of food
establishments suspected of causing a foodborne
illness outbreak.
• A cluster of consumer complaints of illness
• Lab and/or epidemiological information
associated and causative agent identified.
Initial agent and vehicle information may be
limited.
26
Environmental Assessment /
Food Prep Review Objectives
Identify foods and beverages offered
Reconstruct past events - when food(s) were produced
Contributing factors – what
happened?
• Contamination
• Survival
• Proliferation
Identify environmental antecedents – why did this
happen?
Implement effective control actions
27
9
Reconstructing Past Events
Food Preparation
Outbreak
Investigation
12
9
6
Service
2
26
27
28
June
29
30
1
2
3
July
4
5
Health Department Notified
28
Example of Systems-Based
Investigation Results
What happened?
• Cutting board and knife used to cut raw chicken
were then used to slice carrots for the salad.
Why did it happen?
• Employee was unaware of the dangers of crosscontamination.
What can be done now?
• Improve food safety education for employees
SOURCE: EHS-Net
29
“When you have a
foodborne outbreak,
more than one thing
went wrong.”
Dr. Frank Bryan
Centers for Disease Control and Prevention
30
10
C. S. P.
Identify Contributing Factors
• Contamination
• Survival
• Proliferation
31
Contamination
Photos courtesy of Larry Pong
32
Contamination
Receiving, storage,
preparation,transport, service
Worker hands, ill workers
Equipment, utensils
Cross-contamination
Use of leftovers, returned food
33
11
Survival
Ingredients that inhibit growth: acids,
salts, preservative
Time/temperature abuse
Survival on contaminated surfaces,
ingredients
• Bacteria: spores, toxins
• Viruses and parasites
Will the agent survive the process?
34
Proliferation

Nutrients
Availability of oxygen
Temperature
pH
Water activity (aw)
Presence of inhibitory substances
Microbial interactions
Previous stress
Time
35
Steps
Planning
Site visit
• Interviews
• Assessment of food preparation (CSP)
Sampling
Control strategies
36
12
Planning / Preparation:
Review Outbreak Information
Review available Epi information:
•
•
•
•
Dates of onset
Incubation period
Likely exposure dates/meals
For commercial food products
– exact product description
and purchase dates
• Anecdotal information
Review food facility information
• Existing regulatory records
• Menus, recipes, product formulations
Review causative agent information
• Reservoir
• Mode of transmission
37
Knowing the Agent Helps Target
Investigation and Control Measures
HAZARD
Spore-Formers
Preformed Toxins
(i.e. Clost perf, B
cereus, Staph)
Related Contributing Factors to
Investigate During Field Visit
Cooling, Re-Heating, Hot Holding,
Bare Hand Contact, Room Temp Storage, Cold
Holding
Viral Infections
(i.e. norovirus)
Ill Food Worker, Bare Hand Contact,
Handwashing, Contaminated Raw Product
Bacterial
Infections
Ill Food Worker, Bare Hand Contact,
Handwashing, Contaminated Raw Product,
Cross Contamination, Cooking
Parasitic
Infections
Contaminated Raw Product, Contaminated
Source
*See IAFP manual for details on specific diseases
38
Differences in Investigation
Approaches
NO IMPLICATED FOOD:
• Cannot focus on a single item in food prep review in the
early stages of investigation if no food association
established.
• Conduct general risk-based assessment using most up to
date information available
• Determine which samples epi and lab investigators are
most interested in (food, clinical, environmental, water/ice)
IMPLICATED FOOD:
• Food Preparation Review is Key!!
39
13
Other Planning / Preparation
Actions
Develop initial plan and timetable
Assemble materials/personnel
• Pre-meetings w/Lab and Epi

Be sure your equipment kit is stocked
List documents you want to ask for
Alert laboratory
Alert other agencies
40
Site Visit
Manager Interview
Facility walk through
• Assessment of food preparation

Observe operations
Sampling
Worker interviews
Collect records
41
Manager Interviews
Explain reason for
the investigation
Outline investigation
objectives
Create cooperative
relationship
42
14
Manager Interviews (cont.)
Food safety
knowledge
Attitude
Credibility of
information being
provided
43
Manager Interviews (cont.)
Food Worker Health
Review health, hygiene and
education practices
Identify who worked with the
implicated food(s)
Worker ill during time period
of interest?
Reconcile with supervisor
and coworker recollections
Document findings
44
Facility Walk Through
Initial facility walk through
Measure critical operations before
modified
Collect samples while available
Verify who worked with implicated foods
45
15
Observe Operations- General
What process do the foods fit into?
• Process 1 – No Cook Step
• Process 2 – Same Day Service
• Process 3 – Complex Foods
What controls are essential for the foods in
this process?
46
Observe Operations - Specific
How the same items are
prepared today
Attempt to reconstruct how they
were prepared during the time
period of interest
Take measurements (Time,
Temperature Product
Dimensions, Locations)
Recommend using Food Prep
Review Worksheet to
systematically gather
information
47
Laboratory Testing Samples
Food
• Disease causing agents
• Food characteristics
(Ex. pH, water activity)
Environmental
• Document
conditions
48
16
Sampling Issues
Plan your approach in advance as much as
possible (in consultation with lab)
• Type (clinical, food, water, environmental)
• Size
• Number
After reviewing product flow, adjust sampling plan
as needed
Consider need for sampling to pinpoint
contamination source
49
Environmental Sampling
Strategies

In-line
Bracketing
Environmental
Finished product
Consult with lab and
federal agencies for
proper sampling
procedures
50
Environmental Sampling
Strategies (cont.)
Take environmental samples early in the
investigation
Have equipment disassembled for environmental
swabs
Focus on hard-to-clean areas
Chain of custody
51
17
Food Worker Interviews
Interview without manager
present
Recommend asking questions in
chronological sequence
Reconstruct timeline
Let them tell their story
52
Food Worker Interviews (cont.)
Ask about any unusual circumstances that
may have occurred that day--equipment
that wasn’t working, short-staffing,
someone ill
Reword questions when needed, if
information isn’t provided or
inconsistencies are identified
Inconsistent information may indicate
sensitive areas. Consider addressing at
end of interview
53
When Food Workers Cannot
Remember Details
Ask about typical work practices and
routines
Then ask about any unusual events or
changes during time period?
Remember that outbreaks frequently
occur the system was “stressed”
54
18
Concluding the Interviews
Ask if individuals have
unanswered questions or
additional comments
• May have information not
previously considered
• May reveal other useful
information
Leave your business card for future contact
55
Records & Other Information
Sources
What SOPs or food safety systems are in
place?
•
•
•
•
•
•
•
HACCP
Buyer Specifications/Approved Sources
Personal Hygiene
Cleaning & Sanitizing
Time/Temperature Procedures
Recipe Instructions
Menu
56
Compile Information
Compare information
gathered from different
sources (env, lab, epi)
Level of confidence in
information gathered?
What is known and what
remains unknown?
Organize information
needed for final report
57
19
Analyze findings - CSP
Identify CSP at each step
Determine what happened and what did
not
Interpret:
•
•
•
•
Laboratory findings
Time/temperature curves
Food flow diagrams
Food preparation reviews/diagrams
58
Diagram the Process - Food Flow
Receive
Storage
Service
Preparation
Cooking
Cold Holding
Cooling
59
Tracking Food Flow Through
The Facility
60
20
Plot time/temperature curves
61
Precautionary Controls Needed?
Take action to prevent additional cases !
62
Control Actions
Immediately stop the outbreak:
•
•
•
•
•
Hold
Seize
Cease/Desist
License
Menu Limitation
•
•
•
•
Embargo
Closure
Exclusions/ Restrictions
Recalls
Long term strategies to prevent recurrence:
•
•
•
•
HACCP
Risk Control Plans [“Mini-HACCP”]
Training
Menu/Supplier/Recipe Modifications
63
21
Write your report
Work with other disciplines to complete
report and CDC report form, 52.13
Brief narrative
Use visual information summaries
Contributing factors (“What happened”) –
CSP
Environmental antecedents – “Why it
happened”.
64
Key Resources
EHS-Net – see www.cdc.gov
Procedures for Investigating Foodborne
Illnesses Manual - IAFP
65
Summary
YES
Passive
Surveillance
Decide to
Investigate?
N
O
Role
Outbreak
Determination
Confirm if
Outbreak
Occurred?
YES
Outbreak
Investigation/
Environmental
Assessment
N
O
Laboratory
Guidance
Concluding
Actions
Epi.
Helps identify suspect facilities, agents and
food vehicles; serves as link to medical
community, ill people and controls.
Lab.
Provides guidance on sampling techniques;
performs analysis on clinical, environmental
and food samples.
Environ. Performs environmental assessment; helps
implement control measures; serves as link to
the food facility.
66
22
EXERCISE
Graduation Party Blues
Food Preparation Review
On Tuesday, July 2, the Health Department was notified that a number of people who attended a catered
graduation party on June 29 had developed symptoms compatible with foodborne illness. One hundred and
twenty people attended the party; a total of 87 were interviewed, of which 30% were ill. A food specific attack
table was constructed and symptoms were listed; see table I and II attached. The duration of illness range from
8 to 72 hours. The incubation period ranged from 8 to 72 hours with the median being 36 hours. Stool samples
were negative for Salmonella, Shigella and Campylobacter, however, the Laboratory could not test for E. coli.
The following events transpired prior to the graduation party.
Mrs. Sanborne was planning a graduation party for her daughter Chaste. She was a little apprehensive about
preparing food after all her husband always said she couldn't even make a good cup of coffee. Maybe her
neighbor Mrs. Olson could help.
Mrs. Olson recommended Kowalski Caterers. She knew Stella Kowalski, the owner. Mrs. Olson and Stella had
gone to school together. The graduation party was set for Sunday, June 29. Stella discussed the menu with Mrs.
Sanborne and they decided that it would include a chef salad, potato salad, rigatoni with spaghetti sauce,
meatballs and sauce and pea salad. Mrs. Olson had agreed to prepare dessert cake and fruit salad.
Thursday, June 26
Stella felt better today than she did on Tuesday. She had been running a fever and her head felt like a ton of
bricks was resting on it. ''That was one of the bad things about being in business for yourself; you couldn't take a
vacation and still get paid. '' She was on her way to Coward's to pick up the frozen meatballs she would be using
for the graduation party on Sunday. ''I'll put them in the freezer until tomorrow, then I can start thawing them in
the refrigerator. They should be okay.''
Friday, June 27
Stella was feeling her old self again. She picked up the vegetables for the chef salad she was going to make
Sunday and she also bought some grapes, watermelon, honey dew, cantaloupes, strawberries, nectarines and
apples for her friend Tilly Olson. Tilly was going to prepare fruit salad for the graduation party on Sunday.
Frank's market had boxed up all the vegetables and fruits separately for her. Jerry, the owner, selected the fruit
for her. He knew what she liked and he was always reliable.
Saturday, June 28
It was 7:30 A.M. when Stella arrived at the Kitchen. She liked starting early so she could double-check the list of
things to do. Her Kitchen workers, Rita, Lucy and Mary, arrived at 8 A.M. They started to peel the potatoes for
potato salad. While they were doing that, Stella started boiling the eggs. When she was finished, she drained
the water off and put the unshelled eggs into the refrigerator to cool. All of the peeled potatoes were put into a
pot to boil. Next, Rita and Lucy began cutting up all of the vegetables that would go into a salad. When the
potatoes were finished boiling, they were taken off the stove and the water was drained to allow them to cool
down. It was 10 A.M. The hard- boiled eggs were taken out of the refrigerator. Rita and Lucy shelled the eggs
and chopped them up on the cutting board used for the vegetables. The chopped eggs were put into a shallow
pan and removed to the refrigerator. Mary removed the pot of boiled potatoes and set it on the bottom shelf of
the reach-in to cool down.
Mary took out a stainless steel stockpot and put tomato sauce and puree into it. She set it on the stove to cook.
As it was cooking, she added some oregano, basil, garlic and onion powder. Next, she removed the meatballs
from the refrigerator. They had completely thawed since being put there Thursday. She plated the meatballs into
flat bake pans and put them into the oven to bake for about 45 minutes. The sauce was left to cook on the
stove. It was around 1 P.M. Rita and Lucy took the potatoes out of the reach-in and chopped them up on the
vegetable cutting board. Lucy and Rita had cleaned off all the boards just before lunch with soapy water and
then they sprayed them down with the bleach solution Stella made up for them to use. Stella was fussy about
keeping things clean.
1
Rita brought out some large stainless mixing bowls while Lucy took the mayonnaise, chopped celery, onions,
green peppers and the eggs out the refrigerator. Rita dumped the potatoes in equal portions into each mixing
bowl. Lucy added eggs, mayonnaise, celery, onions, green peppers, and vinegar sugar. They mixed the
ingredients in both bowls using a large spoon. The mixing bowl contents were transferred with the same spoon
into 2-inch deep hotel pans, which were covered with tin foil and put into the reach-in refrigerator.
It was 3 P.M. when Mary transferred the cooked meatballs from the preparation table where they had cooled
right after she had removed them from the oven. She covered the meatballs loosely with some tin foil. Next, she
removed the spaghetti sauce from the stove and left it to cool in the stockpot.
Rita chopped up some celery and green onions and then cubed some cheese. She mixed these ingredients in a
large bowl, added canned peas, some pimentos, mayonnaise, and ranch dressing. She mixed the ingredients
by hand. She emptied the contents of the bowl into 4-inch deep plastic pans, covered them and put them into
the reach- in refrigerator. It was 4 P.M. when Mary put the stockpot of spaghetti sauce into the refrigerator to
cool. All three left for home.
Tilly Olson felt sick all day but she had to prepare fruit salad for Sunday's graduation party. She had her son lift
the watermelon out of the refrigerator and onto the counter. She cut the watermelon in half and then cut the fruit
out. She then picked out the seeds by hand and diced the fruit. She did the same with the honeydew melons
and cantaloupes. She took a break and went to the bathroom, came back and rinsed her hands in the sink. She
cored the apples and diced them. She pitted and diced some nectarines. She placed these fruits into the
watermelon halves and added strawberries and red and green grapes. Her son helped her lift the finished
watermelon boats into the refrigerator.
Sunday, June 29
Stella took the van to pick up the fried chickens at Sam and Ella's House of Chicken. She placed several pans of
fried chicken into her van. The chicken was placed into insulated hot boxes she had plugged into outlets
provided in the van. It was 3:00 P.M.
Mary was busy re-heating the spaghetti sauce on the stove that she added all the meatballs to. Lucy was
cooking the rigatoni. Mary let the sauce and meatballs cook while she washed the lettuce, which she then
placed in clear plastic bags. Stella arrived and began helping them pan out the meatballs, spaghetti sauce and
rigatoni into 4-inch hotel pans, which were covered with tin foil and loaded into insulated hot boxes. The covered
plastic pans of pea and potato salad were pulled out of the refrigerator and loaded last. It was 5 P.M. and time to
deliver all the food. Service was scheduled for 6 P.M.
''All the food looks great thought Mrs. Sanborne. I'm glad that Tilly recommended the caterer and it was nice of
her to make up the fruit salad.''
Questions 1-2
1. Using the information provided, complete a food preparation flow diagram for one of the following foods:
meatballs, spaghetti sauce, rigatoni, chef salad, fried chicken, potato salad, pea salad and fruit salad.
2. Complete the food preparation review for one of the food items with the attached form.
2
Table I
FOOD-SPECFIC ATTACK RATES
Food Item
ATE THIS FOOD
ILL
WELL
A.R.
Potato Salad
Chef Salad
Pea Salad
Fried Chicken
Rigatoni
Meat Balls
French Bread
Cake
Fruit Salad
Wine Punch
Peach Schnapps
Beer
Other
20
20
10
23
24
20
26
22
26
9
4
11
13
32
29
27
45
43
48
40
40
33
14
20
18
36
38.46
40.82
27.03
33.82
35.82
29.41
39.39
35.38
44.07
39.13
16.67
37.93
26.53
DID NOT EAT THIS FOOD
ILL
WELL
A.R.
10
10
20
7
6
10
4
8
4
21
26
19
17
25
28
30
12
14
9
17
17
24
43
37
39
21
CHI2= chi-square test
28.57
26.32
40.00
36.84
30.00
52.63
19.05
32.00
14.29
32.81
41.27
32.76
44.74
CHI2
P=
0.52 0.4705
1.40 0.2364
1.06 0.3028
0.00 1.000
0.05 0.831
2.59
0.107
2.09
0.148
0.00
1.000
6.19
0.012
0.08
0.771
3.63
0.056
0.06
0.810
2.39
0.122
P= Percent Probability
Table II
SYMPTOMS OF CASES
Symptom
Number
Nausea
Weakness
Anorexia
Headache
Diarrhea
Abd.Cramps
Chills
Vomiting
Muscle Aches
Perspiration
Fever
Dehydration
Other
28
27
27
24
22
22
22
21
18
16
10
2
2
3
Percent
93.33
90.00
90.00
80.00
73.33
73.33
73.33
70.00
60.00
53.33
33.33
6.67
6.67
NOTES
4
FOOD PREPARATION REVIEW
Complaint Number:
Establishment Name _________________
Address
Phone Number ________________
/
:
AM PM (circle)
Date & Time of Suspect Meal
mo day yr.
Date & Time Food Preparation Started
/
:
AM PM (circle)
mo day yr.
Person Interviewed Name
Position Held:
Review Conducted: _______________________
Other (specify) ______________________________________
Suspect Food ___________________________
DATE
PROCESS
OBSERVATION
AMOUNT
OF
FOOD
TIME
OF DAY
TEMP
OF
FOOD
EQUIPMENT
USED
5
DEPTH OF
CONTAINER
OR FOOD
THICKNESS
HAND
CONTACT
WITH
FOOD
WORKER’S
NAME
WORKER
HEALTH
PRIOR
TO FOOD
PREP
Y
Ill
N
Well
Y
Ill
N
Well
Y
Ill
N
Well
Y
Ill
N
Well
Y
Ill
N
Well
Y
Ill
N
Well
Y
Ill
N
Well
Y
Ill
N
Well
SANITATION
UNUSUAL
EVENTS
OTHER
INFORMATION
1
1. Develop a case definition.
2. Draw an epidemic curve.
3. Develop an initial hypothesis.
4. List three types of study design and a method of statistical
analysis.
5. Calculate measures of association.
6. Interpret significance of data.
7. Determine if hypotheses are confirmed or rejected.
Yes
Notify State
Agency
Assemble Team
Laboratory
Sample
Collection
Repeat as
necessary
Environmental
Assessment
* initiate control actions as appropriate
Assign Tasks
Epidemiologic
Investigation
Step 2: Hypothesis Testing and Analytic Investigation*
Determine
whether an outbreak occured
Step 1: Confirm Outbreak
Refine Case
Definition
Initial Plan
Refine
Hypothesis
Initial Case
Definition
Outbreak
Concluding
Actions (go to
Module 6)
Analyze Data and
Interpret Results
Initial Hypothesis
Task List
Develop an Initial Case Definition and Hypothesis

Develop initial case definitions to be used to determine if an individual is an
outbreak-associated case.

Classify cases in categories based on the certainty of diagnosis.
(Definite/Confirmed, Probable/Presumptive, Possible/Suspect)

Revise and make definitions more specific as new information is received.

Plot cases on an epidemic curve.

Develop/revise hypotheses.
Analyze Data and Test Hypotheses

Determine study design and method of statistical analysis.
• Cohort
• Case-control

Interview identified cases and controls.

Determine if analysis will be done by hand or using computer.

If computer is used, initiate measures to ensure accurate and timely data entry.

Describe extent of outbreak by person, place and time (descriptive analysis).
• Epidemic curves
• Frequency tables
• Spot maps

Calculate measures of association.
• Cohort study – Relative Risk based on attack rates
• Case-control - Odds Ratio based on odds

Interpret results.

Determine if hypotheses are confirmed or rejected.
• If no association found, develop new hypotheses and identify information needed
to test new hypotheses.
• Reanalyze data or gather additional information needed to test new hypotheses.

Organize analyses in preparation for final report and CDC 52.13 form.
Epi-Ready
Epidemiologic Investigation
YES
Passive
Surveillance
Decide to
Investigate?
YES
Outbreak
Determination
NO
Confirm if
Outbreak
Occurred?
Outbreak &
Epidemiologic
Investigation
Laboratory
Guidance
NO
Concluding
Actions
2

Develop a case definition
Draw an epidemic curve
Develop an initial hypothesis
List three types of study design and a
method of statistical analysis
3
MODULE 4: EPIDEMIOLOGIC INVESTIGATION
1
(cont.)
Calculate measures of association
Interpret significance of data
Determine if hypotheses are
confirmed or rejected
4
Develop an Initial Case Definition:
Counting Apples and Oranges
Set of criteria for deciding
whether an individual should be
classified as “ill”
Objective criteria
Outbreak-associated vs.
normal background
• Value of routine surveillance data
• Primary vs. secondary cases
5
Case Definitions
Begin general - become increasingly
specific as information is gathered
• Person, place and time association
• Clinical criteria
• Classify cases based on certainty
Definite/Confirmed
Probable/Presumptive
Possible/Suspect
6
2
Revise Case Definitions
Ongoing throughout investigation
Precise definitions reduce
potential for misclassification
• Estimated 36% of enteric infections
are foodborne
• Incomplete case history can haunt you
• Incorrectly classifying individuals can bias
results
• Make it harder to detect true associations
7
Make Epidemiologic
Associations
Person, Place, Time
Systematically organize
key information
Develop initial hypothesis
8
Person: Frequency Tables
Distribution of age among all respondents
AGE
| Freq Percent
Cum.
------+----------------------21
|
1
2.9%
2.9%
22
|
2
5.7%
8.6%
23
|
4
11.4%
20.0%
24
|
3
8.6%
28.6%
25
|
3
8.6%
37.1%
26
|
2
5.7%
42.9%
27
|
3
8.6%
51.4%
28
|
2
5.7%
57.1%
29
|
1
2.9%
60.0%
30
|
1
2.9%
62.9%
33
|
1
2.9%
65.7%
34
|
3
8.6%
74.3%
35
|
5
14.3%
88.6%
36
|
1
2.9%
91.4%
37
|
2
5.7%
97.1%
39
|
1
2.9%
100.0%
------+----------------------Total|
35 100.0%
9
3
Place: Spot Maps
• 10 people who
died lived closer to
another pump
always sent to pump
in Broad Street
were children
attending school
near the Broad
Street pump
Dr. John Snow, September 1854
10
Place: Common Exposure Location
Examples
•
•
•
•
Case 1 – rest. A, B, C, D
Case 2 – rest. B, E, F
Case 3 – rest. A, B, G, H, I
Case 4 – rest. B, D, J, K
11
Place: Common Exposure Location
(cont.)
Same restaurant
Multiple restaurants, same chain
or owner
Multiple chains, common
distributor
12
4
Time: Frequency Table
Incubation time (in hours) among those who were ill
Current selection: TIMESYMPTO>0
INCUBATION | Freq Percent Cum.
-----------+----------------------------------------10.0
|
1
7.1%
7.1%
11.0
|
1
7.1% 14.3%
24.0
|
7
50.0%
64.3%
25.0
|
2
14.3%
78.6%
26.0
|
2
14.3%
92.9%
34.0
|
1
7.1% 100.0%
-----------+-----------------------------------------Total |
14
100.0%
13
Symptoms: Frequency Table
Frequency of vomiting among those who were ill
Current selection: ILL="Y"
VOMITING | Freq Percent Cum.
---------+-----------------------------------+
|
3
21.4%
21.4%
|
11 78.6% 100.0%
---------+-----------------------------------Total
|
14 100.0%
14
Number of Patients
An Epidemic Curve
12
11
10
9
8
7
6
5
4
3
2
1
0
Fatal
Non-fatal
6/27
8/2
9/6
10/11
11/15
Date
12/20
1/24
2/27
4/3
15
5
Number of Cases
Point-Source Exposure
12
11
10
9
8
7
6
5
4
3
2
1
0
1
3
5
7
9
11
13
15
Days
16
Number of Cases
Ongoing Exposure
12
11
10
9
8
7
6
5
4
3
2
1
0
1
3
5
7
9
11
13
15
Days
17
Number of Cases
Secondary Exposures
12
11
10
9
8
7
6
5
4
3
2
1
0
1
3
5
7
9
11
13
15
Days
18
6
Hypothesis
“An unproved theory
...tentatively accepted to
explain certain facts or to
provide a basis for further
investigation”
Source: Webster’s New World
Dictionary, 3rd Edition
19
Example of Hypothesis
Potato salad consumed
at the Smith wedding
reception caused
illnesses
Data needed to test information
• Who ate potato salad?
• How much did each eat?
• Illness onset (date and time)?
20
Develop Initial Hypothesis
Multiple hypotheses may be
compatible with data initially
Helps clarify
• What is known
• What is missing
• Actions needed to gather
missing information
21
7
When the Causative Agent
is Unknown
Review what is known about cases
• Symptoms, severity of disease
• Events attended or anything unusual
• Foods consumed and methods
of food preparation
Identify most likely agent(s)
• Review references
• Consultation
22
Known Causative Agent
Review what is known about
the agent
• Typical signs and symptoms
• Modes of transmission
• Foods in past outbreaks
Is this situation similar to
other reported incidents?
© Dennis Kunkel Microscopy, Inc.
23
New Routes of Transmission
are Being Identified
E. coli O157:H7 in apple cider
24
8
Case Definition vs. Hypothesis
Hypothesis
Case Definition
•
•
•
•
Person
Place
Time
Symptoms
• Theory
Describes
exposure to test
analytically
Classifies cases
vs. controls
Do NOT include hypothesis in case definition!!!
25
Group Exercise
Case Definition and Hypothesis
Are “cases” associated?
26
Determine study design
• Case Series
• Cohort
• Case- Control
27
9
Case Series
Appropriate to use if:
• Small number of cases (< 5)
• Controls are unavailable
(e.g.,everyone ill)
Provide person, place, and
time associations
28
Cohort Studies
Groups of exposed
and unexposed
individuals can be
easily identified
Compare risk of
illness by what
was/was not eaten
Example: church supper
29
Case-Control Studies
Typically used in foodborne investigations
when:
• Exposed group is very large or
• Exposed group is not easily identified
Compare ill with non-ill
individuals to determine
likelihood of having eaten
specific foods
Examples: very large wedding reception or
sporadic E. coli cases
30
10
Measures of Association Between
Exposure (Food Item) and Disease
Selection of measure depends on type of
study
• “Relative risk”  cohort studies
Risk of developing disease given the exposure
• “Odds ratio”  case-control studies
Odds of having the exposure given the disease
Computer programs greatly speed the
calculations
31
Attack Rate: Measure of Occurrence
Attack Rate (AR)
• Expresses occurrence of a disease among a
particular at-risk population for a limited
period of time, often due to a very specific
exposure.
• Can be event-specific or food-specific
AR =
Number ill people who consumed item
Total number people consuming item
32
Estimating Risks
Associated with “Exposure”
Compare attack rates among exposed and
unexposed
Relative Risk =
Attack Rate (exposed) / Attack Rate (unexposed)
33
11
Using the 2 by 2 Table to
Calculate Relative Risk
Estimates magnitude of association between exposure and
disease in exposed
relative to
group
unexposed group
Disease
Yes ( + )
Yes ( + )
No ( - )
total
a
b
a+b
Exposure
No ( - )
c
d
c+d
total
a+c
b+d
a+b+c+d
RR = 1
RR < 1
RR > 1
a / (a + b)
RR= c / (c + d)
No Association
Negative Association
Positive Association
34
35
Church Supper Cohort Study –
Relative Risk
Vanilla ice cream
• AR (exposed) ÷ AR (unexposed)
79.6 ÷ 14.3 = 5.6
• Persons consuming vanilla ice
cream 5.6 times more likely to
become ill than those who did
not eat vanilla ice cream
36
12
Church Supper Cohort Study –
Relative Risk
Chocolate ice cream
• AR (exposed) ÷ AR (unexposed)
53.2 ÷ 74.1 = 0.7
• Persons consuming chocolate
ice cream were 0.7 times as
likely to become ill than those
who did not eat chocolate ice
cream
37
Using the 2 by 2 Table to
Calculate Odds Ratio
Estimates magnitude of association between exposure and
disease in diseased
relative to non-diseased
group (cases)
group (control)
Disease
Yes ( + )
Yes ( + )
No ( - )
total
a
b
a+b
Exposure
No ( - )
c
d
c+d
total
a+c
b+d
a+b+c+d
OR = 1
OR < 1
OR > 1
= ad
OR = ab /c
/d
bc
No Association
Negative Association
Positive Association
38
Odds Ratio from Case-Control Studies
Measurement of the odds of having an
exposure (specific food consumption)
given the disease
Estimates the Relative Risk derived from
cohort studies
Odds Ratio
Odds of exposure among cases
= Odds of exposure among controls =
(OR)
a/c
b/d =
ad
bc
39
13
How Valid are Your Findings?
Is the observed association
between exposure and disease
due to alternative explanations?
Bias: systematic error (selection,
information {recall, interviewer,
misclassification})
Chance: sampling variability and sampling
size
40
Examples of Bias
Random misclassification of cases vs.
controls or exposed vs. unexposed
• categories of persons less “clean”
• biases OR or RR toward “1”
Recall bias
• cases better remember exposures than do
controls
• problem with retrospective studies
• may result in inflated OR
41
Evaluating the Role of Chance
P value
• Probability a given association could have
occurred by chance alone
• “Statistically significant” defined as p ≤ 0.05
• Consider all available evidence when
interpreting P values
95% Confidence Interval
• Range within which the true association lies,
based on 95% assurance
42
14
P Values and Confidence
Intervals, Example 1
Table 16
Analysis of Food Item 2
ILL
ITEM2
|
+
- | Total
-----------+---------------+-----+ |
5
10 |
15
- |
9
11 |
20
-----------+---------------+-----Total |
14
21 |
35
5 / (5 + 10)
RR= 9 / (9 + 11)
=
.3333
.45
RR= 0.74
95% confidence limits for RR
0.43 < RR < 2.79
Uncorrected P-value = 0.486
43
Intervals, Example 2
Table 15
Analysis of Food Item 1
ILL
ITEM1
|
+
- | Total
-----------+---------------+-----+ |
11
4 |
15
- |
3
17 |
20
-----------+---------------+-----Total |
14
21 |
35
11 / (11 + 4)
RR= 3 / (3 + 17)
=
.7333
.15
RR= 4.89
95% confidence limits for RR
1.65 < RR < 14.50
Uncorrected P-value = 0.000490
44
Intervals, Example 2 (cont.)
Relative Risk (Outcome:ILL=+; Exposure:ITEM1=+) 4.89
95% confidence limits for RR 1.65 < RR < 14.50
Indicates that best estimate of increased risk of
illness associated with consumption of food item
1 is 4.89 times; however, we are 95% confident
that the true risk ratio is no less than 1.65 and
no greater than 14.5 times the risk of those not
consuming this item.
(Lack of inclusion of 1.0 in this interval
demonstrates a significantly positive
association)
45
15
P Value: Effect of Sample Size
Disease
Exposure
+
-
Total
+
4
1
5
-
1
2
3
5
3
8
Fisher’s Exact P value = .46
OR = 8/1 = 8
46
P Value: Effect of Sample Size (cont.)
Disease
Exposure
+
-
Total
+
8
2
10
-
2
4
6
10
6
16
OR = 32/4 = 8
47
P Value: Effect of Sample Size (cont.)
Disease
Exposure
+
-
Total
+
12
3
15
-
3
6
9
15
9
24
OR = 72/9 = 8
48
16
Statistical Summary
• RR is calculated in cohort studies.
• RR compares rate of illness in exposed group to rate of
illness in unexposed group.
• OR is calculated in case-control studies.
• OR = odds in favor of exposure among cases compared to
the odds in favor of exposure among the controls.
• RR and OR are both measures of association.
• “Not Significant” ≠ “No Association” No significance
may reflect lack of association, but may also reflect a
study size too small to detect true association.
49
Take Home Message
If RR or OR = 1, or if the 95 % CI includes 1
then the result is not considered statistically
significant (i.e. there is no statistical difference
between the groups).
If RR or OR is less than 1 may mean food item
is “protective”.
The lower the p-value the more unlikely the
results are due to chance alone.
50
True Story
4 friends meet for dinner
• 3 eat chicken fried rice
• 1 chop suey
3 ill with vomiting & diarrhea 12-18 hrs. after
meal; all 3 ate fried rice
No samples available for testing
Time temperature abuse of fried rice
documented
P value = 0.25
Is this a foodborne outbreak?
51
17
Interpret Results
Hypotheses confirmed or rejected?
• If rejected, develop new hypotheses
• Test new hypotheses by:
More analysis with existing data
Gather and analyze new data
Final conclusions
• Was it foodborne?
52
Summary
YES
Passive
Surveillance
Decide to
Investigate?
Outbreak
Determination
N
O
Role
Confirm if YES
Outbreak
Occurred?
Outbreak &
Epidemiologic
Investigation
N
O
Laboratory
Guidance
Concluding
Actions
Epi.
Develops case definition and hypotheses;
performs descriptive and analytic analyses of
outbreak
Lab.
Helps identify agent and establish case
definition; contributes to epidemiologic
associations
Environ. Helps identify agent and establish case
definition; contributes to epidemiologic
associations
53
Statistics Exercise
Joe’s Thanksgiving Dinner
54
18
Module 4 Case Definition and Hypothesis Exercise
Instructions:
Practice developing case definitions and hypothesis by answering the questions
after reading the scenarios.
It is Monday morning. You have two messages on your answering machine
concerning potential foodborne illnesses. The first involves a husband, wife, and
the second an unrelated female. All reported that they became “ill” within the last
24 hours. The couple both experienced vomiting and diarrhea beginning around
2:00 a.m. Monday morning and claim that the dinner served to them at a Sunday
afternoon church function caused them to be ill. The unrelated female
experienced severe diarrhea and nausea beginning around 10:30 p.m. Sunday
night and claims that the dinner she ate on Sunday night at Kermit’s Kafe caused
her to be ill.
1. Is it time to activate the foodborne illness team? If not, what information
needs to be gathered before doing so?
You call the three cases back and collect a three-day meal history. You find out
that all three cases ate breakfast Friday morning at Becker’s Breakfast Bar. At
the bar, they had four foods in common: scrambled eggs, bacon, fruit salad, and
white toast. Throughout the day on Monday, you receive calls from four more
people with foodborne-related complaints. All of the cases ate at Becker’s
Breakfast Bar on the previous Friday. You find that all seven cases ate
scrambled eggs and bacon. While all seven of the cases had experienced
diarrhea, some also had additional symptoms. Four had experienced vomiting,
four had nausea, and three had abdominal cramps. Fortunately for you, three of
the cases are still having diarrhea and have agreed to provide a stool specimen.
In addition, two cases have leftover bacon & eggs in their refrigerator, which you
will arrange to have tested at your regional laboratory. By this time, you have
alerted your supervisor to the situation and he/she has activated the outbreak
team.
2. Develop a case definition for this outbreak. How many people fit the case
definition?
Environmental health completes their investigation of the food facility on Monday
afternoon. They discovered that the carton of eggs used last Friday had been
left out at room temperature, uncracked, on a counter Thursday night before
being used Friday morning. The other foods appeared to be properly handled
and stored. EH collected the food from the case’s homes and sent it to the lab to
be analyzed. They also discovered that several employees had been sick with
mild diarrhea throughout last week. Two sick employees agreed to submit
samples for lab analysis. All ill employees are restricted from work until they are
symptom free.
So far, no new reports have come in from additional cases. Your outbreak team
meets briefly to discuss the new information.
3. What alternative hypotheses do you have about the cause of this outbreak?
Meanwhile, the personal health unit received a call from another person (a friend
of one of the other cases) who heard that something was going on and wanted to
report that he was also sick after eating at Becker’s. However, his illness wasn’t
that bad and he only had nausea and abdominal cramps. His food history
revealed that he had a bagel, although he did have a bite of his friend’s eggs.
The outbreak team meets again at the end of the day to discuss the new
information.
4. Does this person meet the current case definition?
5. Any changes in case definition or hypotheses?
On Wednesday morning, the lab results have come back on all of the collected
food and stool specimens. All food samples tested negative for bacterial
pathogens while the stool samples (three customers and two food workers)
tested positive for norovirus (norwalk-like virus).
No new reports of foodborne illness have come to the health department.
6. Develop a final case definition for this outbreak (definite, probable, possible
cases)?
7. How many people are in each category?
Module 4 Group Exercise:
OUTBREAK EXERCISE
THE SETTING
The day is the Monday after Thanksgiving. You have just returned from a
weekend with your family, when your friend Joe calls you. He is upset, and
hopes that your public health experience can help him.
He tells you that he had a Thanksgiving dinner on Thursday for many of
the students still in town. During the weekend, over half of the people who
attended the party got ill, experiencing fever, diarrhea, and vomiting. While it
may have just been the flu, Joe suspects their illness may be a result of
something he served at the dinner. He asks you to find out what happened.
First, you ask him about the dinner itself. Joe tells you that preparation for
the dinner started Wednesday night, when he made several pumpkin pies. The
pies included both milk and eggs in the filling. (This filling would be considered a
type of custard.) After baking them, he left them on the counter to cool. They
stayed on the counter until dinner on Thursday, although the recipe said to put
the pies in the refrigerator after they had cooled. On Wednesday night, Joe also
took the turkey out of the freezer and left it on his counter to defrost.
Because of the late night of baking, Joe overslept Thursday morning. He
expected guests to start coming at 1:00, and realized that if he baked the turkey
at the temperature suggested, it could not get done on time. He decided to turn
up the temperature on the oven assuming that the additional temperature would
make up for less baking time. While the turkey was baking he went out to buy
milk. When he returned he set down the bag with the milk in it to speak to a
friend calling on the telephone to ask what he could bring to dinner. Joe forgot to
put the milk in the refrigerator until he noticed it several hours later as he was
passing by the table. He pulled the turkey out of the oven at 12:30. It looked
brown, and felt hot throughout. He made gravy from the turkey drippings, and
served it over potatoes. He then warmed up some beans that had been homecanned for him by his mother.
The dinner started at 1:00 when the guests ate. Along with the turkey,
potatoes, gravy, milk, and beans, Joe also served a gelatin salad and biscuits.
People helped themselves to the pies on the counter all afternoon.
Having learned the characteristics of the dinner, you then wanted to learn
more about the people attending the dinner. You ask Joe for the names of the
people who came to the party. You give these people a call on the phone, and
ask them a list of questions including their experiences of illness since the party
(symptoms, time of onset), what they ate at the party, when they ate, and
whether they saw a doctor about their illness. Some of the data collected is
attached to this exercise. Your objective is to use this data to characterize the
outbreak.
You can approach this exercise as a foodborne disease outbreak.
OUTBREAK EXERCISE
Subject
Sex
Ill
1
F
Y
2
F
Y
3
F
Y
4
M
Y
5
M
Y
6
F
Y
7
M
Y
8
F
Y
9
10
11
12
13
14
15
TOTAL
M
M
M
F
M
M
F
Y
N
N
N
N
N
N
Onset
Sx
Time
Friday
2am
Friday
10am
Friday
5pm
Friday
5pm
Friday
2pm
Friday
3pm
Friday
3pm
Friday
11pm
Friday
7pm
Beans
Gravy Milk
Turkey
Pie
Vomiting
Diarrhea
Fever
N
N
N
Y
N
Y
Y
N
Y
Y
N
Y
Y
Y
Y
N
Y
N
N
Y
N
Y
Y
Y
Y
Y
Y
Y
N
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
N
Y
Y
Y
Y
N
N
N
N
Y
N
N
Y
Y
Y
Y
Y
Y
N
Y
Y
Y
Y
N
Y
Y
Y
Y
Y
12
Y
N
Y
Y
N
Y
Y
10
N
N
Y
N
Y
N
Y
6
N
N
N
N
Y
N
Y
10
Y
Y
N
Y
Y
N
Y
8
N
N
N
N
N
N
N
7
N
N
N
N
N
N
N
8
Y
N
N
N
N
N
N
6
OUTBREAK EXERCISE
Purpose:
You are to determine which food served at Joe’s Thanksgiving dinner caused the
foodborne outbreak. Use the mathematical concepts taught in Module 3 to
determine if there is a statistical association between a given exposure and onset
of illness.
Instructions:
Read the information regarding the background setting of the outbreak. Then
combine into groups to go through the exercise. Please answer the following
questions in order after reading the notes section.
Notes:
A 2x2 table is frequently used to summarize data to show the relationship
between a specific food exposure and subsequent onset of disease. Each case
or control is categorized into one of the four cells in the table.
Disease
Yes
Exposure
No
Yes
a
b
No
c
d
a= the number of individuals who are exposed and have the disease
b= the number who are exposed and do not have the disease
c= the number who are not exposed and have the disease
d= the number who are not exposed and do not have disease
An attack rate (AR) is the proportion of people in a well-defined population that
develop the illness of interest during a limited time period. The greater the
difference between attack rates for those exposed and those not exposed to a
particular food the higher the probability that the food item caused the illness
outbreak.
AR exposed = a/(a+b)
AR unexposed = c/(c+d)
AR exposed - AR unexposed = Risk Difference
The relative risk (RR) is another way of comparing attack rates among exposed
and unexposed persons. Use RR to measure the association between exposure
and disease in a cohort study.
RR= a/(a+b)
c/(c+d)
The odds ratio (OR) also estimates the magnitude of an association between
exposure and disease but is used in case-control studies. The math calculation
is slightly different because you are calculating the odds that someone is at risk
of developing disease given an exposure in an unknown population instead of
the rate of disease development in an exposed known population such as in a
cohort study.
OR= a/c = ad
b/d
bc
Questions:
1. What type of a study would you perform in Joe’s case in order to
determine which food caused the illness? Why?
2. What is the attack rate of people who ate turkey that developed vomiting?
Diarrhea? Fever?
Vomiting:
Diarrhea:
Fever:
3. Fill in the 2x2 table for people who ate pie and became ill.
Disease
Yes
Exposure
to
Pie
No
Yes
No
4. Fill in the 2x2 table for people who ate turkey and became ill.
Disease
Yes
Exposure
to
Turkey
No
Yes
No
5. Calculate the relative risk for developing disease if the subject ate pie.
What does this value mean?
6. Calculate the relative risk for developing disease if the subject ate Turkey.
What does this value mean?
7. Which food item was more likely to cause illness- the Turkey or the pie?
Why?
8. The p-value for the relative risk of the turkey is p=0.03. What does this
mean? What if the p value is p=.65?
1. Determine criteria for testing
2. List key items found in a sample kit
3. Describe the collection of food samples
4. Name the reason for using a chain of custody document
5. Describe the collection of clinical specimens from cases
Task List

Coordinate sampling and analysis strategy with the team and appropriate laboratory prior to
sampling.

Collect leftovers of implicated foods under suspicion.

Collect original food product from the suspect facility.

Collect individual ingredients if complete food product is unavailable.

Collect clinical specimens from ill cases.

Notify appropriate laboratory as to arrival of specimens.

Submit specimens to the laboratory.

Identify what to test to request for a given sample.
Epi-Ready
Laboratory Guidance
Passive
Surveillance
Decide to
Investigate?
NO
YES
Outbreak
Determination
Confirm if
Outbreak
Occurred?
YES
Outbreak &
Epidemiologic
Investigation
Laboratory
Guidance
NO
Concluding
Actions
Laboratory Guidance
2

Determine criteria for testing
List key items found in a sample kit
Describe the collection of food samples
Name the reason for using a chain of
custody document
Describe the collection of clinical
specimens from cases
Laboratory Guidance
3
MODULE 5: LABORATORY GUIDANCE
1
Decision to Test?
Tests performed determined by
local health department
foodborne illness investigation
team
Preliminary epidemiological
associations required prior to
submitting specimens
• Laboratory will examine the most
likely suspect foods first
Laboratory Guidance
4
Criteria To Determine Testing
To Be Performed
Summary of predominant
symptoms
Time interval
Duration of symptoms
Results of prior testing
Communicate with lab and
tell them what they are
testing for
Laboratory Guidance
5
Signs and Symptoms
Upper Gastrointestinal
Neurological
pathogen
C. botulinum
Ciguatera
Scombroid
Shellfish toxin (PSP)
Mushrooms
Chemicals
incubation
12-72h
2-6h
1min-3h
30min-3h
<2h-8h
min-hours
(nausea & vomiting)
duration
days-mos
days-mos
3-6h
days
indefinite
indefinite
Lower Gastrointestinal
(cramps & diarrhea)
pathogen
incubation
B. cereus [Diarrheal]
10-16h
Campylobacter spp.
2-5 days
C. perfringens
8-16h
E. coli 0157:H7
1-8 days
others
1-3 days
Salmonella spp.
1-3 days
Shigella spp.
24-48h
Vibrio cholerae
24-72h
parahaemolyticus 2-48h
Yersinia spp.
24-48h
Giardia lamblia
1-2 weeks
Laboratory Guidance
pathogen
B. cereus [Emetic]
S. aureus
Chemicals
Norovirus
incubation
1-6 h
1-6 h
minutes-hours
12-48 hours
duration
24 h
24-48h
?
hours
Generalized Illness
(fever, chills, sweating, malaise)
duration
24-48h
2-10 days
24-48h
5-10days
3-7 days+
4-7 days
4-7 days
3-7 days
2-5 days
1-3 weeks
days-weeks
pathogen
incubation
Streptococcus spp.
1-3 days
Brucella abortus
7-21days
L. monocytogenes
9-48 h/ 2-6 weeks
Salmonella typhi
7-28 days
Vibrio vulnificus
1-7 days
Hepatitis A
15-50 days
Hepatitis E
15-65 days
Cryptosporidium parvum 2-10 days
Cyclospora spp.
1-14 days
Anisakis
~2 weeks
Trichinella
1-2 days / 2-8 weeks
Toxoplasmosis spp.
5-23 days
duration
weeks
weeks
weeks
weeks
2-8 days
weeks-months
weeks-months
weeks-months
weeks-months
3 weeks
months
months
6
2
Types of Illness
Infection--illness from ingestion
of the organism present in a
food product
•
•
•
•
•
•
•
•
Salmonella spp.
Shigella spp.
Campylobacter spp.
Listeria monocytogenes
Yersinia spp.
Hepatitis A
Norovirus
Vibrio spp.
Campylobacter jejuni courtesy of CDC
Laboratory Guidance
7
Types of Illness
Intoxication-illness from
ingestion of pre-formed toxin
present in the food product
• C. botulinum 1,2
• B. cereus (emetic form) 1,2
• Staphylococcus aureus 2
Clostridium botulinum courtesy of CDC
1 Spore former
2 Toxin producer
Laboratory Guidance
8
Types of Illness
Toxin mediated infection-illness
from ingestion of organism in a
food product followed by toxin
production in the body (toxin is
not present in the food)
• C. perfringens
• B. cereus (diarrheal)
• E. coli O157:H7
E. coli courtesy of CDC
Laboratory Guidance
9
3
Types of Illness
Naturally occurring chemical
toxins present in the food product
• Scombrotoxin
• Ciguatoxin
Photo courtesy of USDA
Laboratory Guidance
10
Interpreting Results
Quantitated pathogens
• S. aureus
• B. cereus
• C. perfringens
Reported as Colony Forming Units/gram or ml of food
Laboratory Guidance
11
Interpreting Results (cont)
Enriched pathogens
•
•
•
•
Salmonella
Vibrio
Listeria
etc.
Reported as Found (Isolated)/Not Found (Not Isolated)
Laboratory Guidance
12
4
Review References
Control of Communicable Diseases Manual
Procedures to Investigate Foodborne Illness
Diagnosis and Management of Foodborne
Illnesses
Laboratory Guidance
13
Additional Considerations
Some foodborne illness investigations will
have the causative agent determined by
epidemiological means.
Laboratory Guidance
14
Submitting Concerns
Submit stool and food specimens
according to the laboratory procedures
and protocols
Vomitus may be an unsatisfactory
specimen for foodborne illness testing
• Check with the testing laboratory regarding
the suitability of this specimen
Laboratory Guidance
15
5
Sampling Kit
Laboratory Guidance
16
Collecting Food Samples
Always ask if food is still available
• At food facility
• At home
Commercially processed foods
• Identity
Product description
Processor information
Lot numbers, expiration dates, use-by
dates
• Integrity (intact packaging preferred)
Laboratory Guidance
17
Sample Collection
All food items should be collected
• As soon as an outbreak is
suspected
• Using aseptic techniques,
including sterile implements
Laboratory Guidance
18
6
Sampling a Solid Food Item
Whenever possible, submit in
original container
100 to 500 grams
For large items, using sterile
utensils, take representative
sample
Transport in sterile, leak-proof
container
Hold under refrigeration until
transported
Transport to the lab on wet ice
Laboratory Guidance
19
Sampling a Solid Food Item
Laboratory Guidance
20
Notice fat
content
Laboratory Guidance
21
7
Sampling of a Liquid Product
Whenever possible, submit in original
container
Stir or shake liquid to ensure sample is
homogeneous
If too large to shake, take multiple
samples
Pour or ladle liquid into leak-proof
container
Hold under refrigeration until transported
Transport to the lab on wet ice
Laboratory Guidance
22
Special Points in
Food Sampling
Official samples vs.
unofficial samples
Take samples early in
investigation
Maintain chain of custody
Equipment disassembly for
environmental swabs
Focus on hard-to-clean areas
Photo courtesy of Larry Pong
Laboratory Guidance
23
Food Sampling Scenario
Visit and evaluate facility
Collect food samples still on hand
Laboratory Guidance
24
8
Food Sampling
Label the samples
themselves
Laboratory Guidance
25
Food Sampling
Keep written records
Laboratory Guidance
26
Food Sampling
Consult with lab staff
Arrange for receipt of sample(s)
Appropriate tests
Laboratory Guidance
27
9
Chain of Custody
Each person signing the form is responsible
for the care and preservation of that sample
while in their possession
Form will account for all persons handling the
sample
•
•
•
•
Who obtained
Who delivered
Who tested
Who disposed
Those signing may be called on to testify in a
criminal proceeding
Laboratory Guidance
28
Chain of Custody
Chronological written record
• Acquisition until final disposition
• Assures continuous accountability
Considered confidential/classified
Maintained in a secure location
Laboratory Guidance
29
Chain of Custody
Each chain of custody form is agency
specific
• If a sample is transferred to a second agency
that agency will start another chain of custody
form for the time that the sample remains in
its custody
• Each agency is responsible for retaining
records regarding sample
Laboratory Guidance
30
10
Collecting the Clinical Specimen
Fecal specimens
• Do not pass directly into tube
• Pass specimen into clean, dry
container that can be discarded
• Follow directions included with
transport medium
• Submit to lab
Include proper paperwork required
by the laboratory
Ship according to current regulations
Laboratory Guidance
31
Collecting the Clinical Specimen
Laboratory Guidance
32
Summary
YES
Passive
Surveillance
Decide to
Investigate?
N
O
Role
YES
Outbreak
Determination
Confirm if
Outbreak
Occurred?
Outbreak &
Epidemiologic
Investigation
Laboratory
Guidance
N
O
Concluding
Actions
Laboratory Guidance
Epi.
Investigation determines most likely agent(s)
and food(s). Lab testing is driven by this
information.
Lab.
Performs testing of clinical specimens and food
samples, confirms suspected agent(s) and
food(s)
Environ. Performs environmental assessment of facility,
collects food samples for testing, and
contributes to epi investigation.
Laboratory Guidance
33
11
*Toxin-mediated infections still result from the
ingestion of the organism. The distinction is
that the organism produces a toxin in the gut
which causes illness – most often diarrhea. No
toxin is produced in the food.
C. perfringens1
B. cereus (Diarrheal)1
E. Coli 0157:H7
Toxin-Mediated Infections*
Hepatitis A
Norovirus
Vibrio
Infection – (illness from ingesting the organism)
Salmonella
Campylobacter
Listeria
Yersinia
Shigella
Trichinella
Anisakis
1 – Spore Former
2 – Toxin Producer
Intoxication- (illness from toxin formed in the food)
C. botulinum1-2
B. cereus (Emetic) 1-2
Staphylococcus2
Other- (naturally occurring chemical toxins)
Scombrotoxin
Ciguatoxin
Neurological
duration
24 h
24-48h
?
Upper Gastrointestinal*
incubation
1-6 h
1-6 h
minutes-hours
(nausea & vomiting)
pathogen
B. cereus [Emetic]
Staph aureus
Chemicals
Norovirus
12-48 hours
hours **
*May involve other symptoms, especially diarrhea
Flu Mimicking***
duration
days-mos
days-mos
3-6h
days
forever?
forever?
Lower Gastrointestinal* *
(fever, chills, sweating, etc.)
pathogen
incubation
C. botulinum
12-72h
Ciguatera
2-6h
Scombroid
1min-3h
Shellfish toxin (PSP) 30min-3h
Mushrooms
<2h-8h
Chemicals
min-hours
(cramps & diarrhea)
incubation
duration
pathogen
incubation
duration pathogen
B. cereus [Diarrheal]
10-16h
24-48h
Streptococcus
1-3 days
weeks
Campylobacter
2-5 days
2-10 days Brucella abortus
7-21days
weeks
C. Perfringens
8-16h
24-48h
Listeria
9-48 h/ 2-6 weeks weeks
E. coli 0157:H7
1-8 days
5-10days Salmonella typhi
7-28 days
weeks
others
1-3 days
3-7 days+ Vibrio vulnificus
1-7 days
2-8 days
Salmonella
1-3 days
4-7 days
Hepatitis A
15-50 days
weeks-months
Shigella
24-48h
4-7 days
Hepatitis E
15-65 days
weeks-months
Vibrio cholerae
24-72h
3-7 days
Cryptosporidium
2-10 days
weeks-months
parahaemolyticus 2-48h
2-5 days
Cyclospora
1-14 days
weeks-months
Yersinia
24-48h
1-3 weeks Anisakis
~2 weeks
3 weeks
Giardia
1-2 weeks days-weeks Trichinella
1-2 days / 2-8 weeks months
Toxoplasmosis
5-23 days
months
**May involve other symptoms – esp. vomit, fever, ***May not include all symptoms, such as fever. Note
that “Flu” is a respiratory illness unrelated to foods!
but diarrhea is pronounced.
Control Measures
• Approved Source
– Freezing to -4oF for 7 days or -31oF for 15 hours
• Usually not practical to do this in a retail or food service facility
– Fishing from Ciguatera-free waters
– Temperature Control to prevent Scombroid
• Control from the time of catch to the time of service
• Preventing Cross-Contamination
– Separating RTE from raw
– Cleaning and sanitizing equipment and food contact surfaces
• Personal Hygiene Control
– Employee Health
– Handwashing
– No Bare Hand Contact with RTE Food
Chicken
Ground Beef
Pork
Fish
• Cooking
–
–
–
–
• Hot Holding
• Cooling
Control Measures
165oF for 15 seconds
155oF for 15 seconds
145oF for 15 second
145oF for 15 second
135oF or above
– 135oF to 41oF in 6 hours….provided that…
– 135oF to 70oF in 2 hours
• Reheating
– 165oF for 15 seconds within 2 hours
SUGGESTED KIT FOR COLLECTING SAMPLES DURING AN INVESTIGATION OF A
FOODBORNE OUTBREAK
Equipment
Containers, screw-cap, single use
Water sample bottles
(bacteriological)
Water sample bottles (partial
chemical)
Whirl paks 6"x9" or similar size
Large plastic bags that can be
sealed
Ice paks
Styrofoam cooler
Pipettes*
Spatulas*
Scoops, 1 tbsp in size*
Swab material w/ transport
container
Gloves, nitrile or latex, medium
size
Aluminum foil
Tongs*
Metal stem thermometer or
thermocouple
Chain of custody forms or
documentation protocol
IAFP "Procedures to
Investigate Foodborne Illness"
manual
Field investigation forms, rec.
forms from IAFP manual or equivalent
Requisition forms for samples
sub to regional labs
Cardboard box(es)
Treatment
Sealed, sterilized
Sterilized, containing
sodium thiosulfate,
mailers
In mailers
Sterilized
Sterilized
Liquid/solid food specimens
Coliform water sampling
Nitrate water sampling or
solid/liquid samples
Solid foods
Transport/cooling specimens
Frozen, may be reusable
Intact, unused
Sterilized, individually
wrapped
wrapped
wrapped
wrapped
wrapped
Sterilized or from
unopened container
wrapped
In protective case,
sanitized before use
---------------
Legal purposes
---------------
Reference Material
---------------
Investigation/record keeping
---------------
Laboratory submission of
specimens
Shipment of specimens for
analysis
Shipment of specimens for
analysis
Labeling of samples
Sanitize thermometer
Securing packaging around
samples
Sealing shipping containers
Guidance
---------------
Shipping labels
---------------
Waterproof permanent markers
Alcohol swabs
Rubber bands
-------------------------------------------
Tape, waterproof
Food sampling directions
-----------------------------
*Items that may be single use.
Purpose
Cooling/preservation
Transport/cooling specimens
Liquid sampling
Solid sampling
Solid/Liquid sampling
collect surface samples
Sampling/handling of large
food items
Wrapping large solid food items
Solid sampling
Measure food temperatures
SOURCES
Materials for Foodborne Disease Investigation Kits
International BioProducts, Inc.
P.O. Box 2728
Redmond, WA 98073
1-800-729-7611
Thomas Scientific
99 High Hill Road @ I-295
P.O. Box 99
Swedesboro, NJ 08085
1-800-345-2100
VWR Scientific
800 E. Fabyan Pkwy
Batavia, IL 60510
1-8000-932-5000
Cole Parmer
325 E. Bunker Court
Vernon Hills, IL 60061-1844
1-800-323-4340
Fisher Scientific
1600W. Glenlake Ave.
Itasca, IL 60143
1-800-766-7000
Weber Scientific
2732 Kuser Road
Hamilton, NJ 08691
1-800-328-8378
Gempler’s
100 Countryside Dr.
P.O. Box 270
Belleville, WI 53508
1-800-382-8473
NASCO
901 Janesville Ave.
Fort Atkinson, WI 53538-0901
1-800-558-9595
Lab Safety Supply Inc.
P.O. Box 1368
Janesville, WI 53547-1368
1-800-356-0783
Ben Meadows Company
3589 Broad Street
Atlanta, GA 30341
1-800-241-6401
All QA Products, Inc
3427 SW 42nd Way
Gainesville, FL 32608
1-800-845-8818
Omega
One Omega Drive
P.O. Box 4047
1-800-826-6342
Module 6: Concluding Actions
1. Describe the need to inform the public.
2. Identify control strategies that need to be implemented.
3. Document the results of the outbreak investigation.
4. Describe means for using investigative data for prevention.
5. Explain the importance of an after action group review to
improve coordination and action in the future.
Analyze Data and
Interpret Results
(Module 3)
Inform Public
Implement
Control
Strategies
Prepare Final
written repot and
CDC form 52.13
Module 6:
Outbreak Concluding Actions
Use investigative
Data for
prevention
Module 6: Outbreak Concluding Actions
Task List
Implement Control Strategies

Initiate or finalize control strategies to prevent additional cases of foodborne illness.

Identify method(s) of assessing compliance with control measures.

Coordinate actions with state and federal agencies when multiple jurisdictions are
involved.
Inform Public

Determine if there is an ongoing public health threat.

Alert the public to both the potential hazard and methods of reducing risks.

Keep records for future reference.
Write Final Report & Submit CDC 52.13

Prepare final written report.

Complete CDC form 52.13 if necessary
Use Investigative Data for Prevention

Hold investigation team meeting to review investigation and findings.

Identify risk factors that caused or contributed to the outbreak.

Determine the extent of high-risk practices.

Develop a plan to reduce risk factors.

Communicate findings to those who can put them into practice.

Hold investigation team meeting to review outbreak investigation process.

Develop recommendations for improving future outbreak investigations.
Epi-Ready
Concluding Actions
Passive
Surveillance
Decide to
Investigate?
YES
NO
Outbreak
Determination
Confirm if
Outbreak
Occurred?
YES
Outbreak &
Epidemiologic
Investigation
Laboratory
Guidance
NO
Concluding
Actions
Concluding Actions
2

Describe the need to inform the public
Identify control strategies that need to be
implemented
Document the results of the outbreak
investigation
Describe means for using investigative data for
prevention
Explain the importance of an after action group
review to improve coordination and action in
the future
Concluding Actions
3
MODULE 6: CONCLUDING ACTIONS
1
Concluding Actions
Implement
Control
Strategies
Analyze Data and
Interpret Results
Prepare Final
Written Report
and CDC form
52.13
Use
Investigative
Data for
Prevention
Inform
Business/Public
Concluding Actions
4
Concluding Actions
Putting the pieces together
Feedback
Concluding Actions
5
Implement Control Strategies
Strategies to prevent further
illness/exposure
Assess compliance
Coordinate with other affected agencies
Concluding Actions
6
2
Examples of Regulatory
Tools

Hold
Seize
Embargo
Cease/desist

License/menu limitation
Closure
Exclusions /restrictions
Recalls
Concluding Actions
7
Inform the Public
Public’s right to know:
Inform the public if an
ongoing threat exists
Population susceptibility
Concluding Actions
8
Risk Communication
Public announcement must:
Explain potential risk
Provide measures to reduce risk
Concluding Actions
9
3
Using the Records We Keep
Epidemiological
Environmental
Laboratory
Public Health Nursing
Concluding Actions
10
Report Writing
If you don’t clearly communicate your
findings, no one benefits from all of
your hard work.
“A job isn’t complete until the paperwork is done.”
Concluding Actions
11
Do’s of Report Writing
Gather each discipline’s
summary
Be short and to the point
Include attacks rates,
frequencies and epi curve
Include information
requested in CDC eFORS
form 52.13
Concluding Actions
12
4
Do’s of Report Writing
Gather each discipline’s summary
Be short and to the point
Include attacks rates, frequencies and
epi curve
Include information requested in CDC
eFORS form (52.13)
Concluding Actions
13
Report Writing
Concluding Actions
14
Final Report Format
1.
2.
3.
4.
5.
Cover Page
Summary
Description of Outbreak
Introduction/Background
Methods- environmental,
epidemiology & laboratory
6. Results- environmental, epidemiology
& laboratory
7. Discussion
ry
l
gy
to
8. Recommendations
lo
ta
ra
o
io
en
b
m
a
m
9. Acknowledgements
e
L
on
id
Ep
v ir
10. Appendices
En
Concluding Actions
15
5
Cover Page

Unique name of outbreak
Date of outbreak
Place of outbreak
Agencies involved in investigation
Author(s) of report
Concluding Actions
16
Summary
Basic Epi information – who, where, when
& what
Environmental findings
Laboratory results
Actions taken for resolution
Lessons learned
Recommendations
Concluding Actions
17
Introduction & Background
Brief introduction about the place of
outbreak
Background surveillance
Similar outbreaks in the past
Specific information about the facility –
restaurant, convention center, school etc.
Concluding Actions
18
6
Description of Outbreak
How was the outbreak detected?
Subsequent actions – initial response to
the outbreak
Initial control measures
Any collaborations (FDA, USDA, CDC…)
Media
Concluding Actions
19
Methods: Environmental

Evaluation of facility and personnel
Food preparation review
Food flow diagram
Food sources (labels, tags, invoices)
Samples collected
Contributing Factors
Concluding Actions
20
Methods: Epidemiology
Descriptive Epidemiology
Hypothesis
Type of study – case control, cohort
etc.
Definitions – case, control etc.
Statistics – software, description of
statistical test used.
Specimen(s) collected
Concluding Actions
21
7
Methods: Laboratory
Food samples – descriptions of types,
contents
Specimens – stool, urine, blood etc.
Type of tests conducted – culture, PFGE
etc.
Concluding Actions
22
Results: Environmental
Results of Inspection
Actions taken - follow up inspection,
closure of restaurant
Training
Contributing Factors
Concluding Actions
23
Results: Epidemiology
Descriptive Epidemiology – details
Analytical Epidemiology
Tables – Epi curve, food attack rate table
etc.
Details of statistical analysis
Concluding Actions
24
8
Results: Laboratory
Food samples
Specimens – stool, urine, blood etc.
Interpretation of results
Concluding Actions
25
Discussion
Hypothesis accepted/rejected:
Strength of association
• Magnitude of odds ratio or relative risk
Consistency of data
• Internally (this investigation)
• Externally (with other investigations)
Temporality (cause precedes effect)
Concluding Actions
26
Discussion (cont’d)
Biologic plausibility
Dose-response relationship
• Example: Consistent increase in attack rate
as number of servings consumed increases
Coherence with known (published)
information about the disease
Experimental evidence
Concluding Actions
27
9
Discussion (cont’d)
Study limitations
Control measures
Lessons learned
Concluding Actions
28
Recommendations

Education of employees
Education of community
Preventive measures to avoid reoccurrence
Follow up actions
Concluding Actions
29
Acknowledgements
Outbreak team
Collaborative people, organizations
Community
Concluding Actions
30
10
Appendices

Statistical tables
Correspondence
Educational material
Media related items
Publications (references)
Concluding Actions
31
CDC eFORS form 52.13
Concluding Actions
32
Use Investigative Data
for Prevention
Hold team meeting
to debrief
• What went right
• What could have
been improved
Surveillance
Investigation
Prevention and
education
Concluding Actions
33
11
Team Investigation Debriefing
Develops useful foodborne disease data
bank
Useful in the event of litigation
Reinforces necessity and success of
teamwork approach
Reliable, complete information provides
ability to determine foodborne disease
trends, incidence and causal factors
Concluding Actions
34
Team Investigation Debriefing
(cont.)
Essential for detecting and evaluating new
foodborne disease hazards and risks
Allows for preparation of public report
outlining investigation findings
Establishes good community relations
Concluding Actions
35
Summary
A successful outbreak investigation involves
a systematic approach relying on
disciplines to operate as a T.E.A.M where:
Together
Everyone
Achieves
More
Concluding Actions
36
12
Summary
YES
Passive
Surveillance
YES
Outbreak
Determination
Decide to
Investigate?
N
O
Confirm if
Outbreak
Occurred?
Outbreak &
Epidemiologic
Investigation
Laboratory
Guidance
N
O
Concluding
Actions
Role
Concluding Actions
Epi.
Prepares final report; provides summary of descriptive epi.
and data analysis; utilizes results of the investigation to
prevent future outbreaks; informs public.
Lab.
Prepares final report; provides summary of samples,
analysis and results.
Environ.
Prepares final report; provides summary of environ.
assessment; enforces control measures and utilizes results
of the investigation to prevent future outbreaks.
Concluding Actions
37
13
OUTBREAK REPORT TEMPLATE
Outline
1) Cover Page
2) Summary (abstract)
3) Introduction and Background
4) Description of outbreak
5) Methods – Environmental, Epidemiology, Laboratory
6) Results – Environmental, Epidemiology, Laboratory
7) Discussion
8) Recommendation
9) Appendices
10) Acknowledgements
Details
Cover Page:
1) Unique name of Outbreak
2) Name of person submitting report
3) Date of Outbreak (Time period)
4) Agencies involved in outbreak investigation
5) County, District (if that is not included in the "unique name")
Summary:
1) Basic Epi Info – who, where, when and what
2) Environmental findings
3) Lab results
4) Actions taken for resolution of problem.
5) Lessons learnt and recommendations made to prevent reoccurrence
Introduction and background:
1) Brief introduction about the place (city, town etc.) and population.
2) Background surveillance, endemic disease?
3) Similar outbreaks in the past.
4) Specific information about the facility i.e. restaurant type, convention center etc.
1
Description of outbreak:
1) How was the outbreak detected? (Who got the initial call)?
2) Subsequent actions – response to confirm the outbreak (hypothesis generating
interviews, getting in touch with hospitals, clinics, contacts etc.)
3) Initial control measures initiated
4) Any collaboration (USDA etc.), media management, if any.
Methods
Environmental:
1) Evaluation of affected facility and personnel
2) Samples collected.
3) Food preparation review
4) Any Trace back required
Epidemiology:
1) Epi description – who, where, when and what.
2) Hypothesis.
3) Case and control definition.
4) Specimens collected.
5) Analyses done - software used, study type (Case control, cohort study
etc.)
Type of statistics (e.g. chi square etc.)
6) Risk factors
Laboratory:
1) Food samples and specimens (description of type and contents).
2) Type of tests done (Bacterial culture, EIA, PFGE etc.)
Results
Environmental:
1) Critical and non-critical violations.
2) Action taken (downgrading).
3) Follow up Inspection.
Epidemiology:
1) Details (description) of cases and controls
2) Foods implicated
3) Epi curve, other tabulations (attack rate table etc.)
4) Results of statistical analysis.
2
Laboratory:
1) Results of food samples and specimen testing (include molecular type
results etc.)
2) Interpretation.
Discussion:
1)
2)
3)
4)
Hypothesis accepted/rejected and reasons (epidemiological, statistical etc.)
Study Limitations.
Control measures taken and results.
Lessons learnt for outbreak team.
Recommendations:
1) Education of employees, employees put on sick leave.
2) Community education
3) Means to prevent future outbreaks.
4) Any follow up action.
Appendices:
1) Questionnaire
2) Statistical tables
3) Educational material used etc.
4) Letters sent to Participants, physicians etc.
5) Any media related items (press release, newspaper stories)
6) Publications.
Acknowledgements:
1) Outbreak team
2) Collaborative members (USDA, university, hospital etc.)
3) Community members.
Note:
1)
2)
3)
4)
5)
Method to be devised to de-identify personal information (HIPPA).
Secure storage of reports.
Retention schedule.
Disposal at the end of retention schedule.
Appropriate use of outbreaks reports for educational purposes.
3
EXAMPLE REPORT
Maple Rapids Church Youth Group Program
Campylobacter jejuni Outbreak
Investigation Report
Maple Rapids
Clinton County, Michigan
Date of Incident: October 29, 2003
Number of Ill Persons: 6
Prepared by:
Mid-Michigan District Health Department
Norm Keon, Epidemiologist
December 23, 2003
EXAMPLE REPORT
Introduction:
On Wednesday, November 12th, a public health nurse at our Gratiot Branch Office was
notified by a physician’s assistant (PA) from a family practice in Alma that they were
treating an eleven year old girl who had laboratory confirmed Campylobacter jejuni. The
girl claimed that other children in her church were also ill with similar symptoms and that
they had all attended a meeting of their youth group on Wednesday, October 29th. They
had been practicing for a play and were served a snack at that gathering. It was the PA’s
belief that an outbreak had occurred in this group and he was alerting the local health
department to this possibility.
Environmental:
Methods:
No environmental health actions were taken in response to this outbreak. Our CD nurse
requested information from the mother of the index case concerning what foods were
served at the meeting.
Results:
It was determined that a limited number of foods were served. They consisted of
cinnamon rolls, frosting, and milk. However, a relative of one of the mothers had
supplied the milk from their dairy farm and it was unpasteurized. Since we were notified
fourteen days after this event there was no milk available for testing.
Epidemiology:
Case finding:
Our communicable disease nurse notified our medical director and epidemiologist. She
also contacted the mother of the index case and obtained additional information about the
youth group from her. The mother reported that approximately eight children were ill.
Our epidemiologist notified the Disease Control office at the Michigan Department of
Community Health (MDCH) that we had an outbreak of campylobacter possibly related
to raw milk consumption and would be submitting stool specimens. The name of the
outbreak was “Maple Rapids Church.” A line listing was started based on information
provided by the mother of the index case.
Questionnaire/Analysis:
A questionnaire was designed, and a database was created utilizing Epi-Info. The
questionnaire was delivered to the mother of one of the ill girls who served as the
supervisor for the group of children. She had agreed to distribute it at their next meeting.
Case definition:
A case was defined as any person who attended the October 29th meeting of the youth
group and within 2 to 5 days subsequently experienced vomiting and/or diarrhea.
2
EXAMPLE REPORT
Results:
Descriptive Analysis
(Note: since we had limited completion of our questionnaires, some of this data
has been abstracted from information provided by informants)
Persons attending the meeting: 20 (approx.)
Persons who completed a questionnaire: 5 (25%)
Ill persons who met the case definition: 6
Attack rate among those attending: 30 %
Age:
Range 8 - 41
Mean 15.2
Median 11.0
Sex:
Female 83 %
Male 17 %
Symptom frequencies and percentages:
Diarrhea
6 100 %
Bloody stools 2
9%
Vomiting
4
67 %
Cramps
6
100 %
Fever
3
50 % (Mean 102 deg.)
Chills
2
33 %
Headache
4
67 %
Nausea
5
83 %
Soreness
1
17 %
Sought medical care:
Hospitalized:
3
0
50 %
0%
Incubation period (hours):
Range
33.5 – 74.5
Mean
60.8
Median
67.5
Duration of illness (days):
Range
2.5 – 8.0
Mean
5.2
Median
5.0
Statistical Analysis
Due to the low response rate of completed questionnaires it was not possible to
conduct two-way table analyses for the individual food items.
3
EXAMPLE REPORT
Laboratory:
Methods:
Stool examination was completed at the Gratiot Community Hospital laboratory for the
index case. Our CD nurse, after consulting with our epidemiologist, requested that
several other persons who had been ill submit specimens to the State Laboratory at
MDCH. She provided stool collection kits to four persons with mailing instructions.
None were submitted. However, a sample from one child was sent by her physician to
the Sparrow Hospital Laboratory.
Results:
The following line list summarizes the laboratory findings for the two children mentioned
above.
Age/Sex Lab
11yo/M GCH
11yo/F Sparrow
Onset Date
11/01
10/31
Date Collected
Results
11/07
Positive for C. jejuni
11/17
Positive for C. jejuni
Conclusions:
We gathered illness and exposure data (of varying completeness) on nine individuals who
attended a church youth group meeting. Two children had stool specimens positive for
Campylobacter jejuni. This organism has a reservoir in animals, particularly cattle and
poultry. That fact, combined with the fact that few other food items were served in
addition to the raw cow milk, lends validity to our hypothesis that this outbreak was
caused by the ingestion of the raw milk. However, since all of the milk was either drank
or disposed of we had no samples to test. Due to the lack of complete epidemiological
data we were unable to determine if there was a dose-response relationship evident with
milk consumption.
We received poor cooperation from this group of people in completing the questionnaires
and in submitting stool specimens. A possible explanation was the religious orientation
of these families and their possible distrust of government.
Recommendations:
We advised the youth group supervisor and several other mothers during our contacts
with them that the consumption of raw milk is a confirmed risk for the acquisition of a
number of zoonotic diseases of public health importance and that we do not recommend
this practice.
4
Number of Cases
6
5
4
3
2
1
0
27
30
31
1
2
November
3
4
Maple Rapids Church Youth Group Program
Campylobacter Outbreak
Onset of Illness by Date
Maple Rapids (Clinton County) -- Oct/Nov 2003
29
Youth Group Meeting 5:30pm
28
October
EXAMPLE REPORT
Cases
Campylobacter+ Cases
EXAMPLE REPORT
EXAMPLE REPORT
FORM APPROVED
OMB NO.0920-0004
CDC USE ONLY
INVESTIGATION OF A FOODBORNE OUTBREAK
__ __–__ __ __ __ __ __
This form is used to report foodborne disease outbreak investigations to CDC. A foodborne outbreak is
defined as the occurrence of two or more cases of a similar illness resulting from the ingestion of a
common food in the United States. This form has two parts: Part 1 asks for the minimum data needed and
Part 2 asks for additional information. For this investigation to be counted in the CDC annual summary,
Part 1 must be completed. We encourage you to complete as much of Part 1 and Part 2 as you can.
STATE USE ONLY
____________________
Part 1: Required Information
1. Location of Exposure:
2. Dates:
3. Numbers of Cases Exposed:
Date first case became ill:
State: MI
Multi-state exposure
_1 0__ / _3_ _1_ / _2_ _0_ _0_ _3_
Month
Day
Year
Date of first known exposure: _1_ _0_ / _2_ _9__ / _2_ _0_ _0_ _3_
County: _Clinton_______
Multi-county exposure
Month
List other states/counties in
Comments, bottom of this page
Day
Year
Date of last known exposure: _1_ _0_ / _2_ _9_ / _2_ _0_ _0_ _3_
Month
Day
Lab-confirmed cases:
Probable cases:
__2__ (A)
__4__ (B)
Estimated total ill: _____
(If greater than sum of A+B)
Year
Please send epidemic curve, if available.
4. Approximate Percentage of Total
Cases in Each Age Group:
percent of total cases)
<1 year: _____% 20-49 yrs: _17__%
1-4 yrs: _____%
6. Investigation Methods: (Check all that apply)
5. Sex: (Estimated
⌧ Interviews of cases only
Case-control study
Cohort study
Food preparation review
Food product traceback
Male: __17_ %
> 50 yrs: _____%
Female: __83_ %
5-19 yrs:__83_%
7. Implicated Food(s): (based on
Reasons listed in Item 15 on page 3)
Factory or production plant
Source investigation
(farm, marine estuary, etc.)
Environment / food sample cultures
8. Etiology: (Name the bacteria, virus, parasite, or toxin. Include specific details on toxin or
______Raw milk_____________
organism, such as phage type, virulence factors, molecular fingerprinting, antibiogram, metabolic
profile. Criteria for confirmed etiologies are defined in MMWR 1996 / Vol. 45 / ss-5 / Appendix B.)
___________________________
Etiology
Serotype (if avail.)
Campylobacter
jejuni
___________________________
___________________________
___________________________
Etiology undetermined
More than one etiology
(Please list in Comments)
Could not be determined
Isolated/identified from (check all that apply):
⌧ Patient specimen(s)
Food specimen(s)
Environment specimen(s)
Food worker specimen(s)
9. Contributing Factors: (See list on page 2, check all that apply)
10. Agency reporting this outbreak:
Contributing factors unknown
Contamination Factor:
C1
C2
C3
C10
C11
C12
Mid-Michigan District Health Dept.__________
Contact Person:
C4
C5
C13
C14
⌧C6
P11
⌧ P12 (describe in Comments)
⌧C7
C8
C15 (describe in Comments)
Proliferation/Amplification Factor (bacterial outbreaks only):
P1
P2
P3
P4
P5
P6
P10
Other Characteristics
P7
P8
C9
N/A
P9
N/A
Survival Factor (microbial outbreaks only):
S1
S2
S3
S4
⌧ S5 (describe in Comments)
__Norm Keon______________________
TITLE:
___Epidemiologist __________________
PHONE NO:
_989-831-5237
FAX NO:
___989-831-5522
E-MAIL:
_nkeon@cmdhd.org
_______________
______________
_______
Date of completion of this form:
N/A
Was food-worker implicated as the source of contamination?
Yes
If yes, please check only one of following:
laboratory and epidemiologic evidence
epidemiologic evidence (w/o lab confirmation)
lab evidence (w/o epidemiologic confirmation)
prior experience makes this the likely source (please explain in Comments)
NAME:
No
_1_ _2_ / _ 2_ _3__ / _2_ _0_ _0_ _3_
Month
Day
Year
Initial Report
Updated Report
⌧ Final Report
Additional data suggests this is not a
foodborne outbreak
Comments: ________________________________________________________________________________________________
Page 1
CDC 52.13
REV. 8/1999
EXAMPLE REPORT
FORM APPROVED
OMB NO.0920-0004
This questionnaire is authorized by law (Public Health Service Act, 42 USC §241). Although response to the questions asked is voluntary, cooperation of the patient is necessary for the
study and control of disease. Public reporting burden for this collection of information is estimated to average 15 minutes per response. Send comments regarding this burden estimate or
any other aspect of this collection of information, including suggestions for reducing this burden to PHS Reports Clearance Officer; Rm 721-H, Humphrey Bg; 200 Independence Ave. SW;
Washington, DC 20201; ATTN: PRA, and to the Office of Information and Regulatory Affairs, Office of Management and Budget, Washington, DC 20503.
The following codes are to be used to fill out Part 1 (question 9) and Part 2 (question 15).
1
Contamination Factors:
C1 - Toxic substance part of tissue (e.g., ciguatera)
C2 - Poisonous substance intentionally added (e.g., cyanide or phenolphthalein added to cause illness)
C3 - Poisonous or physical substance accidentally/incidentally added (e.g., sanitizer or cleaning compound)
C4 - Addition of excessive quantities of ingredients that are toxic under these situations (e.g., niacin poisoning in bread)
C5 - Toxic container or pipelines (e.g., galvanized containers with acid food, copper pipe with carbonated beverages)
C6 - Raw product/ingredient contaminated by pathogens from animal or environment (e.g., Salmonella enteriditis in egg, Norwalk in
shellfish, E. coli in sprouts)
C7 - Ingestion of contaminated raw products (e.g., raw shellfish, produce, eggs)
C8 - Obtaining foods from polluted sources (e.g., shellfish)
C9 - Cross-contamination from raw ingredient of animal origin (e.g., raw poultry on the cutting board)
C10 - Bare-handed contact by handler/worker/preparer (e.g., with ready-to-eat food)
C11 - Glove-handed contact by handler/worker/preparer (e.g., with ready-to-eat food)
C12 - Handling by an infected person or carrier of pathogen (e.g., Staphylococcus, Salmonella, Norwalk agent)
C13 - Inadequate cleaning of processing/preparation equipment/utensils – leads to contamination of vehicle (e.g., cutting boards)
C14 - Storage in contaminated environment – leads to contamination of vehicle (e.g., store room, refrigerator)
C15 - Other source of contamination (please describe in Comments)
Proliferation/Amplification Factors:1
P1 - Allowing foods to remain at room or warm outdoor temperature for several hours (e.g., during preparation or holding for service)
P2 - Slow cooling (e.g., deep containers or large roasts)
P3 - Inadequate cold-holding temperatures (e.g., refrigerator inadequate/not working, iced holding inadequate)
P4 - Preparing foods a half day or more before serving (e.g., banquet preparation a day in advance)
P5 - Prolonged cold storage for several weeks (e.g., permits slow growth of psychrophilic pathogens)
P6 - Insufficient time and/or temperature during hot holding (e.g., malfunctioning equipment, too large a mass of food)
P7 - Insufficient acidification (e.g., home canned foods)
P8 - Insufficiently low water activity (e.g., smoked/salted fish)
P9 - Inadequate thawing of frozen products (e.g., room thawing)
P10 - Anaerobic packaging/Modified atmosphere (e.g., vacuum packed fish, salad in gas flushed bag)
P11 - Inadequate fermentation (e.g., processed meat, cheese)
P12 - Other situations that promote or allow microbial growth or toxic production (please describe in Comments)
Survival Factors:1
S1 - Insufficient time and/or temperature during cooking/heat processing (e.g., roasted meats/poultry, canned foods, pasteurization)
S2 - Insufficient time and/or temperature during reheating (e.g., sauces, roasts)
S3 - Inadequate acidification (e.g., mayonnaise, tomatoes canned)
S4 - Insufficient thawing, followed by insufficient cooking (e.g., frozen turkey)
S5 - Other process failures that permit the agent to survive (please describe in Comments)
Method of Preparation:2
M1 - Foods eaten raw or lightly cooked (e.g., hard shell clams, sunny side up eggs)
M2 - Solid masses of potentially hazardous foods (e.g., casseroles, lasagna, stuffing)
M3 - Multiple foods (e.g., smorgasbord, buffet)
M4 - Cook/serve foods (e.g., steak, fish fillet)
M5 - Natural toxicant (e.g., poisonous mushrooms, paralytic shellfish poisoning)
M6 - Roasted meat/poultry (e.g., roast beef, roast turkey)
M7 - Salads prepared with one or more cooked ingredients (e.g., macaroni, potato, tuna)
M8 - Liquid or semi-solid mixtures of potentially hazardous foods (e.g., gravy, chili, sauce)
M9 - Chemical contamination (e.g., heavy metal, pesticide)
M10 - Baked goods (e.g., pies, eclairs)
M11 - Commercially processed foods (e.g., canned fruits and vegetables, ice cream)
M12 - Sandwiches (e.g., hot dog, hamburger, Monte Cristo)
M13 - Beverages (e.g., carbonated and non-carbonated, milk)
M14 - Salads with raw ingredients (e.g., green salad, fruit salad)
M15 - Other, does not fit into above categories (please describe in Comments)
M16 - Unknown, vehicle was not identified
1
Frank L. Bryan, John J. Guzewich, and Ewen C. D. Todd. Surveillance of Foodborne Disease III. Summary and Presentation of Data on
Vehicles and Contributory Factors; Their Value and Limitations. Journal of Food Protection, 60; 6:701-714, 1997.
2
Weingold, S. E., Guzewich JJ, and Fudala JK. Use of foodborne disease data for HACCP risk assessment. Journal of Food Protection, 57;
9:820-830, 1994.
Page 2
CDC 52.13
REV. 8/1999
EXAMPLE REPORT
Part 2: Additional Information (Please complete as much as possible)
11. Numbers of:
Cases with
Outcome /
Symptom
OUTCOME / SYMPTOM
Total cases for whom you
have information available
12. Incubation
Period:
3
6
Shortest:
33.5_
Hospitalization
0
6
Longest:
74.5
Death
0
6
Median:
67.5_
4
6
6
6
Bloody stools
2
6
Feverish
3
6
Abdominal cramps
6
6
* Headache
4
6
Diarrhea
Recovered:
(Hours)
Healthcare Provider Visit
Vomiting
13. Duration of Acute Illness
Among Those Who
(Hours)
Shortest: _2.5_
Longest: _8.0_
Median:
(Hours, days)
_5.0_
Unknown
* Use the following terms, if appropriate, to describe other
common
characteristics of cases:
descend
ing
paralysi
s
flushing
headach
e
hemolyti
c uremic
anaphylaxis
arthralgia
bradycardia
bullous skin
lesions
bradycardia
cough
coma
diplopia
*
*
myalgia
paresthesia
septicemia
sore throat
tachycardia
thromobocytopenia
temperature reversal
urticaria
wheezing
*
14. If Cohort Investigation Conducted:
Event-specific Attack Rate = __________________ / _____________________________________ x 100 = ______ %
# of exposed cases
# of exposed individ. for whom you have illness info.
15. Implicated Food(s): (Please provide known information.
Name of Food
e.g., lasagna
Main Ingredients
pasta, sauce, eggs, beef
ALSO ATTACH FOOD SPECIFIC ATTACK RATE TABLE)
Reason(s) Suspected
Contaminated Ingredient
(see below)
eggs
4
Raw milk
Method of Preparation
(see list on page 2)
M1
1 3
M1
Food vehicle could not be determined
Reason Suspected
(choose all that apply):
1 - Statistical
evidence from epidemiological
investigation
2 - Laboratory
evidence (e.g., identification of
agent in food)
3 - Compelling
supportive information
4 - Other data (e.g., same phage type found on farm that supplied eggs)
5 - Specific evidence lacking but prior experience makes this likely source
16. Where was Food Prepared? (Check all that apply)
Restaurant or deli
Day care center
School
Church, temple, etc.
Camp
Caterer
Grocery store
Hospital
Workplace cafeteria
Nursing home
17. Where was Food Eaten? (Check all that apply)
Prison, jail
Private home
Picnic
Fair, festival, other temporary/mobile service
Contaminated food imported into U.S.
Commercial product, served without further
preparation
⌧ Other (please describe)
__________________
⌧ Unpublished agency report
Epi-Aid
Publication (please reference)
_____________________________
19. Remarks: Briefly describe important aspects of the outbreak not covered above
(e.g., restaurant closure, product recall, immunoglobulin administration, economic impact, etc.)
Minimal cooperation from this group in completion of exposure history
and submission of stool specimens
Page 3
REV. 8/1999
Nursing home
Prison, jail
Private home
Picnic
Fair, festival, or mobile
location
Other (please describe)
__Direct from dairy farm_____________
18. Other Available Info:
CDC 52.13
Restaurant or deli
Day care center
School
⌧ Church, temple, etc.
Camp
Grocery Store
Hospital
Workplace cafeteria
EXAMPLE REPORT
Part 2: Additional Information (Please complete as much as possible)
Not available
____________________________________________________________
____________________________________________________________
____________________________________________________________
MI Local Health Departments: Please mail this document to Food and Dairy Division, Michigan Dept. of Agriculture
State Health Departments: Please FAX this document to Biostatistics and Information Branch, DBMD, CDC, at (404) 639-2780.
Page 4
CDC 52.13
REV. 8/1999
Group Exercise:
A Multistate Outbreak of E. coli O157:H7 Infection Group
Organization Instructions
1. Select a group leader.
The leader guides group discussions and activities, keeps the group on
time and is the group's liaison to the facilitator's.
2. Select a group secretary.
The secretary records information as needed. In the exercise you are
about to do, the secretary will construct an epi curve and timeline during
the group's discussion.
3. Select a group listener.
The listener can participate and be involved in discussions, but should
mainly listen. The listener, under the guidance of the group leader, points
out when one of the six problems listed below is occurring. The listener
helps make sure that the discussion is balanced, with everyone getting
equal opportunity to talk and be heard.
REMEMBER:
1. Set preconceived notions aside and be open to the ideas that will be
expressed.
2. Be open to changing your mind.
3. React to ideas not people.
4. Respect others, don't interrupt, argue with, antagonize, belittle or discredit
the person speaking.
5. It is inappropriate to blame, change the subject, ignore someone's ideas or
assume you know other peoples motives.
6. Don't formulate your response while others are speaking. Listen to them
and then respond.
7. Your group’s answer to each question should also indicate which
module(s) in the Epi-Ready training addressed the topic.
Outbreak Recognition:
In June 1997, local health agencies identify an increase in lab confirmed E. coli
O157:H7 infections. In June 1996, there were 18 infections. However, in June
1997, there were 52 infections.
Person:
Michigan Residents with Outbreak Strain,
June 15 – July 15, 1997
•
•
•
•
•
68% Female
96% Bloody Diarrhea
54% Hospitalized
2 Persons HUS
0 Deaths
Place:
Oakland
Midland
Kent
Washtenaw
Livingston
Kalamazoo
Cheboygan
13
8
6
6
6
4
1
Emmet
Ingham
Gratiot
Gladwin
Ottawa
Wayne
Total
Time:
1
1
1
1
1
1
50
Initial Questions:
1. Is this an outbreak? Why or why not?
2. What could account for the increase in cases reported to Michigan
Department of Community Health (MDCH)?
3. What additional information would you want to gather initially as part of
your investigation?
4. What clues does the epi. curve provide about the nature of the
exposure(s)?
Update 1- Laboratory Findings
MDCH laboratory reports that during the period June 1 – July 31 1997:
• 60 infections in 16 counties (compared to 31 infections in same period in
1996)
• Of 60 infections, 54 isolates were available for sub typing
• 40 of the 54 isolates were identical by PFGE
Example: PFGE Analysis -
*
indicate bands are identical
Laboratory Evidence
PFGE Analysis
**
****
** **
**
****
** **
Question 2:
a) What do the above laboratory results tell you about the strain(s) of E. coli
0157:H7 identified?
b) What would your group use as an initial case definition for this outbreak?
Initial Case Definition Developed by Investigation Team:
A case was defined as diarrhea (≥ 3 loose stools a day) and/or abdominal
cramps in a resident in Michigan with onset of symptoms between June 15 and
July 15 and a stool culture yielding E. coli O157:H7 with the outbreak strain
PFGE pattern.
Question 3:
What are the advantages and disadvantages of this case definition? How might
you change it?
Update 2- Additional Case Information:
•
•
•
•
•
Oakland County - Not many ate meat. Most ate vegetables.
Midland County - 4 of 6 at Restaurant X salad bar
Kent County - Near vegetarians. Salad eaters.
Washtenaw County - 5 of 6 cases female; no links.
Ingham County - 1 case: Box lunch of mostly vegetables
Compare the age and gender distribution of E. coli O157:H7 cases from the
Michigan outbreak and those reported from the U.S. FoodNet sites in 1997.
Question 4:
Who at the local health department do you think gathered the case
information for these laboratory confirmed outbreak-related cases?
Question 5:
What hypothesis might explain the pattern of disease in this outbreak? Source of
agent? Mode of transmission?
Epidemiologic Study Design
Question 6:
What kinds of questions would you ask in the hypothesis-generating interviews?
Be sure to consider all possible modes of transmission of E. coli O157:H7.
Question 7:
How would you choose controls for this study?
Question 8:
Over what time period would you examine exposures to possible risk factors for
cases? For controls?
Case Control Study: Local health, Michigan Dept of Ag,
Michigan Dept of Community Health and CDC
MDA
TRACEBACKS
MDCH
CDC
July 16
SUBTYPING
CASE CONTROL STUDY
OF
30 CASES
•
•
•
•
56% of cases ate alfalfa sprouts within 7 days of illness
6% of controls ate alfalfa sprouts
Matched Odds ratio = 27 (95% confidence interval 5-558)
No other food items significantly associated with illness
Hypothesis =
Alfalfa Sprouts
Question 9:
What are possible explanations for the association between illness and sprouts?
Question 10:
How might you explain the 12 ill persons in the study who did not report eating
alfalfa sprouts in the 7 days before they became ill?
Question 11:
What control measures might you consider at this point?
Traceback Investigation
Question 12:
What information would be needed before undertaking a traceback investigation?
I.
Key
G = Grocery
Store
R = Restaurant
D1 =Distributor 1
D2 =Distributor 2
A = Sprout
Grower 1
B = Sprout
Grower 2
Traceback Results:
Retail Level Traceback
Distribution and Production
Level Tracebacks
SOURCES OF ALFALFA SPROUTS
CASES
G
R
G
R
R
G
R
G
R
G
R
R
R
G
R
G
G
R
R
R
G
R
G
R
G
R
R
R
G
R
G
R
G
R
G
R
R R
G
R
SPROUT
R R
DISTRIBUTOR
D1
D2
D3
D4
D5
D6
D10
8 Grocery stores
13 Restaurants
D7
D8
D9
SPROUT
B
A
GROWER
Alfalfa Seed Supplier Traceback
Sprout
Growers
B
A
*
*
*
Lot 123
Lot 123
Sprout Seed
Distributor - KY
K
Seed supplier - ID
S
IF
IF
IF
C
48 cases
E. coli 0157:H7
96% MICH 1a
Lot 123
IF
IF
CA Storage
WF
Virginia outbreak
discovered to be occurring
at the same time. Sprouts
implicated as cause.
- 48 cases
- 46 identical to MI
strain
- Associated w/
Virginia sprout
grower C
*No insanitary conditions or E. coli 0157:H7 found from
environmental samples
IF = Idaho Farms
Question 13:
Who gathered this information and how do you interpret these results?
APPENDIX 1
FOODBORNE ILLNESS GLOSSARY
2 x 2 table - a tabular cross-classification of data such that subcategories of one
characteristic are indicated horizontally (in rows) and subcategories of another
characteristic are indicated vertically (in columns). Tests of association between
characteristics in the columns and rows can be readily applied. Also known as
contingency tables. The simplest contingency table is the fourfold or 2 x 2 table.
Contingency tables may be extended to include several dimensions of classification.
Exposed
Not Exposed
Ill
a
c
Not Ill
b
d
Asymptomatic - without symptoms.
Attack rate - the proportion of a well-defined population that develops illness over a
limited period of time, as during an epidemic or outbreak. It is often expressed as a
percentage. The difference between attack rates for those exposed and non-exposed
to a particular food provides important clues in the investigation of the etiology of an
acute outbreak.
Carrier - a person or animal that harbors a specific infectious agent, is asymptomatic,
and is a potential source of infection for man or animals
Case - in epidemiology, a person in the population or study group identified as having
the particular disease, health disorder, or condition under investigation. A variety of
criteria may be used to identify cases (e.g., individual physicians' diagnoses, registries
and notifications, abstracts of clinical records, surveys of the general population,
population screening, reporting of defects such as in a dental record).
Case-control study – a type of observational analytic study. Enrollment into the study
is based on the presence (“case”) or absence (“control”) of disease. Characteristics
such as previous exposures are then compared between cases and controls.
Case definition – a set of criteria used for investigative purposes to decide whether a
person has a particular disease or whether a person is to be included in a “case”
category by specifying clinical and laboratory criteria and by specifying limitations on
time, place and person. This definition may be used differently in various phases of an
investigation. For example, a broad definition might be used early in an investigation to
capture all possible cases, while later in the investigation, the definition might be
narrowed to capture only definite cases. Often, a “possible” and “confirmed” case
definition are generated, with the latter being cases with, for example, a positive
laboratory test in addition to symptoms.
Chain of custody - a record that establishes the complete chronological disposition of
an entity of concern (e.g., laboratory specimen, document).
APPENDIX 1
Cluster - aggregation of cases of a disease or other health-related condition, which are
closely grouped in space and time. The number of cases may or may not exceed the
expected number.
Cohort study – type of observational analytic study. Enrollment in the study is based
on exposure characteristics or membership in a group. Disease, death, or other healthrelated outcomes are then ascertained and compared.
Commercial confidential – trade secrets protected by law from public disclosure (e.g.,
monitoring records, customer lists, traceback information). Unlawful release of this
information can result in legal punishment, including imprisonment.
Common source outbreak - outbreak that results from a group of persons being
exposed to an infectious agent or toxin from a single source.
Confidence intervals (CI) - the computed interval with a given probability (e.g., 95%,
that the true value of a variable such as a mean, proportion, or rate is contained within
the interval). This is a measure of statistical significance; if a confidence interval
includes the value 1.0, it means that there is no association between the exposure in
question and the outcome.
Confirmed cases – a case that has met the case definition and with a laboratoryidentified etiology.
Contact – exposure to a source of an infection, or a person so exposed.
Confirmed outbreak - clusters (see above) which are confirmed by laboratory or
epidemiologic study to be caused by a common agent or among persons who have
shared a common exposure.
Contact – exposure to a source of an infection, or a person so exposed.
Contaminant - an infectious agent or a chemical or physical hazard.
Contamination - the presence of an infectious, chemical, or physical agent or
substances in or on water, milk, and food that has the potential to cause harm, including
illness or injury.
Controls – in a case-control study, comparison group of persons without
disease/illness.
Epidemic - the occurrence of more cases of disease than expected in a given area or
among a specific group of people during a particular period of time.
APPENDIX 1
Epidemic curve (Epi curve) - a histogram that shows the course of a disease outbreak
or epidemic by plotting the number of cases by time of onset. Epidemic curves help
characterize an outbreak and give clues about the source of the outbreak (e.g.,
common or point source, secondary spread, etc.)
Epidemiology – the study of the distribution and determinants of health-related states
or events in specified populations, and the application of this study to the control of
health problems.
Firm - any individual, partnership, corporation, or association that deals in articles
subject to the FD&C Act.
Food-specific attack rate - the food-specific attack rate table compares the illness rate
among those who ingested specific foods at an event or meal to the illness rate of those
who were at the event or meal but did not ingest these food items.
Food worker - person directly involved in producing, harvesting, processing,
packaging, preparing, or storing the food under investigation.
HACCP (Hazard Analysis and Critical Control Point) - a prevention-based food safety
system. HACCP is a system that identifies and monitors specific foodborne hazards biological, chemical, or physical properties - that can adversely affect the safety of the
food product. This hazard analysis serves as the basis for establishing critical control
points (CCPs). CCPs identify those points in the process that must be controlled to
assure the safety of the food. Further, critical limits are established that document the
appropriate parameters that must be met at each CCP. Monitoring and verification
steps are included in the system, again, to assure that potential risks are controlled.
The hazard analysis, critical control points, critical limits, and monitoring and verification
steps are documented in a HACCP plan.
Host - a person or other living organism that can be infected by an infectious agent
under natural conditions.
Hypothesis - A supposition arrived at from observation or reflection that leads to
refutable predictions. Any conjecture cast in a form that will allow it to be tested and
refuted.
Implicated food - Food thought to be the outbreak vehicle (i.e. food thought to have
made people ill, based on laboratory results and/or epidemiological evidence).
Incubation period - The time period between exposure to an infectious agent and the
onset of signs and symptoms of disease.
Index case - the first case among a number of similar cases that are epidemiologically
related.
APPENDIX 1
Infection - the entry and development of multiplication of an infectious agent in the
body of man or animals. Infection is not synonymous with infectious disease: the result
may not be apparent or manifest. The presence of living infectious agents on exterior
surfaces of the body is called "infestation" (e.g., pediculosis, scabies). The presence of
living infectious agents upon articles of apparel or soiled articles is not infection, but
represents contamination of such articles.
Line List - a table listing case names, age, sex, onset time, residence, symptoms,
employment, etc., which facilitates comparisons of many characteristics for possible
similarities or associations.
Matching - the process of making a study and comparison group comparable with
respect to extraneous factors. Individual matching relies on identifying individual
subjects for comparison, each resembling a study subject on the matched variables
(e.g., age, gender). Studies using matching in the interview phase use matching in the
statistical analysis.
Measure of association - a quantified relationship between exposure and disease.
Commonly used measures of association are differences between means, proportions
or rates, rate ratio, odds ratio, relative risk, and correlation and regression coefficients.
Odds Ratio (OR) – a measure of association which quantifies the relationship between
an exposure and health outcome from a comparative study. The term odds is defined
differently according to the situation under discussion. Using a standard 2 x 2 table, the
odds ratio (cross-product ratio) is ad/bc.
Exposed
Not exposed
Ill
a
c
Not Ill
B
D
Onset – the time the first clinical signs or symptoms begin to occur.
Outbreak – same as epidemic. Limited to localized increases in the incidence of a
disease (e.g., in a village, town, or closed institution).
Pathogen - organism capable of causing disease (literally, causing a pathological
process).
APPENDIX 1
Pesticide - any substance or mixture of substances intended for preventing, destroying,
repelling, or mitigating any pest. Pests can be insects, mice and other animals,
unwanted plants (weeds), fungi, or microorganisms like bacteria and viruses. Though
often misunderstood to refer only to insecticides, the term pesticide also applies to
herbicides, fungicides and various other substances used to control pests. Under
United States law, a pesticide is also any substance or mixture of substances intended
for use as a plant regulator, defoliant, or desiccant. Common pesticides include:
algaecides, antifouling agents, anti-microbials, attractants, biocides, disinfectants and
sanitizers, fungicides, fumigants, herbicides, insecticides, miticides, microbial
pesticides, molluscicides, nematicides, ovicides, pheromones, repellents, rodenticides,
defoliants, desiccants, insect growth regulators and plant growth regulators
(http://www.epa.gov/opp00001/whatis.htm).
Point source outbreak – see common source outbreak.
Proliferation/amplification factors – factors that allow proliferation of the etiologic
agents:
1. Allowing foods to remain at room or warm-outdoor temperature for several hours
2. Slow cooling
3. Inadequate cold-holding temperature
4. Preparing foods a half-day or more before serving
5. Prolonged cold storage for several weeks
6. Prolonged time and/or insufficient temperature during hot holding
7. Insufficient acidification
8. Insufficiently low water activity
9. Inadequate thawing of frozen products
10. Anaerobic packaging or modified atmosphere
11. Inadequate fermentation
Probable Cause – a case without laboratory confirmation that has typical clinical
features of the particular disease under investigation without laboratory confirmation.
p-value – a measure of the chance the observed results would occur if the null
hypothesis were true. The probability associated with a statistical hypothesis will help
decide if there is a significant association between exposure and illness or if the results
are due to chance (coincidence).
Questionnaire – a predetermined set of questions used to collect data (e.g.,
demographics, clinical data, social status, occupational group).
Rate – an expression of the frequency with which an event occurs in a defined
population.
APPENDIX 1
Recall – A firm’s voluntary removal or correction of a marketed product(s), including its
labeling and/or promotional materials, that FDA or FSIS considers to be in violation of
the laws it administers, and which the agency would initiate legal action (e.g., seizure or
the full range of administrative and civil actions available to the agency). “Recall” does
not include a market withdrawal or stock recovery.
Regulatory authority – Agency that regulates (permits/licenses and inspects) the
substance or establishment under consideration.
Relative Risk (RR) –
1. The ratio of the risk of disease or death among the exposed to the risk among the
unexposed; this usage is synonymous with risk ratio.
2. Alternatively, the ratio of the cumulative incidence rate in the exposed to the
cumulative incidence rate in the unexposed (i.e., the cumulative incidence ratio).
3. The term relative risk has also been used synonymously with odds ratio. The use of
the term relative risk for several different quantities arises from the fact that for “rare”
disease (e.g., most cancers) all the quantities approximate one another. For
common occurrences (e.g., neonatal mortality in infants under 1500g birth weight),
the approximations do not hold.
Reservoir – the habitat, in which an infectious agent normally lives, grows and
multiplies; reservoirs include human reservoirs, animal reservoirs, and environmental
reservoirs.
Sample size determination – the mathematical process of deciding, before a study
begins, how many subjects should be studied. The factors to be taken into account
include the incidence or prevalence of the condition being studied, the estimated or
putative relationship among the variable in the study, the power that is desired, and the
allowable magnitude of type I error.
Serotype (or serovar) – a subdivision of a species or subspecies distinguishable from
other strains therein on the basis of antigenic character.
Source (point of contamination) – the person, animal, object, or substance from which
an infectious agent passes to a host. Source of infection should be clearly distinguished
from source of contamination, such as overflow of a septic tank contaminating a water
supply or an infected cook contaminating a salad.
Sporadic case – occurring irregularly and infrequently (e.g., cases of certain infectious
diseases) also, a case NOT associated with a known outbreak.
Statistically significant association – statistical methods allow an estimate to be
made of the probability of the observed or greater degree of association between
independent and dependent variables under the null hypothesis. From this estimate, in
a sample of given size, the statistical “significance” of a result can be state. Usually the
level of statistical significance is stated by the p-value.
APPENDIX 1
Strength of association – the magnitude of the measure of association (see above);
for example, the size or value of the odds ratio is a measure of the strength of
association between an exposure and an illness or other outcome. The larger the odds
ratio, the stronger the association.
Study design – the procedures and methods, predetermined by an investigator, to be
adhered to in conducting a research project.
Subtype – see serotype
Surveillance – the detection of health problems through the appropriate collection of
data, followed by its collation, analysis, interpretation, and dissemination.
Active surveillance – agencies regularly contact reporting sources to elicit
reports of illnesses. An active surveillance system is likely to provide more
complete illness reporting but is more labor intensive and costly to operate.
Passive surveillance – agencies receive disease reports from physicians,
laboratories, the public, and institutions as mandated by state law.
Susceptible – a person lacking sufficient resistance to a particular disease agent to
prevent disease if or when exposed.
Survival factors - factors that allow survival or fail to inactivate the contaminant:
1. Insufficient time and/or temperature during cooking or heat processing
2. Insufficient time and/or temperature during reheating
3. Inadequate acidification
4. Insufficient thawing followed by insufficient cooking
Suspect Cases- persons meeting part of the case definition (see above); for example,
persons with specific symptoms (and, perhaps, exposure to a food item of interest) who
do not have a laboratory test confirming the cause of their illness; can also refer to
persons with laboratory-confirmed illness who are not known to have the exposure of
interest.
Suspect Outbreak – a cluster of cases linked by time or space which has not been
confirmed to be caused by the same agent or item (exposure) but which have
characteristics (e.g., an unusual organism or exposure) which makes it likely that the
cases are linked not by chance alone.
Suspect food - food from the implicated meal that is a likely vehicle for the causative
agent. These foods are often identified by the Food Specific Attack RateTable.
Symptomatic - demonstrating clinical signs or symptoms (e.g., diarrhea, abdominal
pain, fever).
APPENDIX 1
Time/temperature abuse - Insufficient time and/or temperature during cooking or heat
processing, insufficient time and/or temperature during reheating.
Traceback – the method used to determine the source and scope of the
product/processes associated with the outbreak and document the distribution and
production chain of the product that has been implicated in a foodborne illness or
outbreak.
Traceforward - once the source of an implicated food item is established, investigators
may do a "traceforward" to document the distribution of all implicated lots of food from
the source. This can help epidemiologists with case finding and can be used to test
hypotheses about the outbreak. Traceforwards should only be used when there is a
reasonable degree of confidence that the traceback correctly identified the source of the
implicated product.
Vector – an animate intermediary in the indirect transmission of an agent that carries
the agent from a reservoir to a susceptible host.
Vehicle (of infection transmission) - an inanimate intermediary in the indirect
transmission of an agent that carries the agent from a reservoir to a susceptible host.
Sources for Glossary
A Dictionary of Epidemiology, 3rd edition, John M. Last, ed. New York: Oxford
University Press, 1995
Principles and Practice of Public Health Surveillance, Steven M. Teutsch and R. Elliott
Churchill, eds. NY: Oxford University Press.
Stedman's Medical Dictionary, 26th edition, Baltimore: Williams and Wilkins, 1995.
Procedures to Investigate Foodborne Illness, 5th edition, IAMFES.
Food Code, U.S. Public Health Service, Food and Drug Administration, 1999.
FDA Satellite Training: Foodborne Illness Investigations, March 16-18, 1999.
FDA Satellite Training: Traceback of Fresh Produce and Other Commodities, June 1617, 1999.
EPA website: http://www.epa.gov/opp00001/whatis.htm
APPENDIX 2
COMMUNICATIONS
This information is intended to supplement information contained in other
emergency management plans and documents.
Goal: an involved, reasonable, and solution-oriented public
Share what is known and what is not known.
Provide factual objective information.
Avoid complex scientific jargon.
Use concrete examples that help put risks into proper context.
Effective communication promotes public confidence in the agency handling
the issue.
Time information sharing to maximize impact;
• Make sure informed staff are available to answer questions
• Meet media deadlines (e.g., no later than 4:00 p.m. for evening news)

The following are specific communication issues related to foodborne illness
outbreak investigations that should be considered:
I. Preparation
Develop standard operating procedures for when and how to inform the
media and public about food safety situations and emergencies.
Coordinate with communications staff to prepare clear, concise, and complete
message(s).
Designate one spokesperson per agency to ensure consistent information is
delivered.
Identify venues for coordinating communications when multiple agencies are
involved.
II. Outbreak Response
Collect accurate information on investigation and response activities.

Always follow individual agency’s communications policy to provide
information to:
• News media
• Public
• Government officials
Educate the spokesperson about the key outbreak-related facts, disease
process, and investigation methods being used so that questions are
effectively answered and everyone has the same correct information.
Share information with your staff so they do not need to get their information
from the media.

APPENDIX 2

•
•
•
•
•
•

•
•
•
•

Make sure messages answer:
Who
What
When
Where
How
Why
Provide clear and specific prevention and control.
Provide only objective, factual information that emphasizes public health
protection.
Do not release preliminary information that has not been confirmed.
Notify health care providers, and emergency room staff about the situation to
enhance surveillance efforts.
Coordinate releases of information with involved local, state, and federal
agencies so agencies are “on the same page” and up-to-date on situation
details.
Inform local officials prior to going public.
Attempt to provide media and public with “one stop shopping” source of
information, and always try to:
Return phone calls even when you have nothing new to tell.
Anticipate media information needs and respond to media requests even if
you have nothing new to report.
Provide regular updates in readily accessible format (e.g., briefings in a
central location).
Consider setting up emergency hotline, extra phone lines, fax and web pages
to help meet communication needs.
Provide updates frequently while the situation is rapidly evolving then reduce
as it stabilizes.
III. Termination
As situation improves or changes, terminate emergency measures no longer
needed.
Monitor and evaluate the situation after the investigation is completed to
ensure the outbreak has been effectively controlled and that no new cases
are occurring.
Write final investigation report to share with involved agencies and interested
parties.
APPENDIX 3
INTERVIEWING SKILLS
Acknowledgement: The majority of this information was abstracted from the training
program “Foodborne Illness Investigations” March 1999 developed by the FDA’s State
Training Branch.
I. Task List
A. Prior to Interviews

Identify specific interviewing objectives.
Identify the persons to be interviewed.
Select the questionnaire content and format (open-ended vs. closed-ended).
Assign and prepare staff who will be interviewing.
B. During Interviews

Ask questions as written if closed-ended questionnaire is being used.
Review form before ending interview to ensure fully complete.
C. After the interview

Turn in questionnaires to be reviewed (quality control).
Enter information into database as soon as possible.
Keep track of who has been interviewed and who is interviewing.
APPENDIX 3
II. Task List Related Information
A. Prior to Interviews

Identify specific interviewing objectives
•
What information must be collected?
− The source of the illness
− Means of transmission.
•
How to gather it?
− Target questions to the greatest degree possible so that relevant information
is gathered the first time.
− Minimize the number of repeat contacts.

Identify the persons to be interviewed.
•
Attempt to understand the individuals involved.
− Remember that the goal is to get the facts as they occurred without biasing
the results.
− Consider what language and format are appropriate to avoid creating
intimidating atmosphere;
Demographic factors include age, gender, background, and occupation.
Involvement in the incident that could create roadblocks.
Ö Potential for defensiveness
Ö Angry about becoming ill (food preparation)
Ö Confused about their involvement
− Investigators typically need to gather information from diverse people;
Physicians and health care providers,
People at the function (both ills and wells),
Owner of the establishment, and
Cooks, kitchen crew, and wait staff.
− Someone may try to work against you.
Document the information provided.
Check with other sources to verify accuracy and check consistency.
APPENDIX 3

Select the questionnaire content and format (open-ended vs. closed-ended).
•
Core information that should be gathered during every outbreak investigation
includes;
− Demographic data (e.g., age, sex, address, phone number).
− Food history of typically 72 hours. Recognize that this may need to be altered
for certain foodborne pathogens (E. coli 0157:H7, Listeria momcytogenes,
Hepatitis A).
Foods consumed and specific locations of facilities where foods were
consumed or purchased (include address whenever possible).
Times of consumption.
Potential extent of exposure (who else consumed the food?).
Ö Gather contact information.
For commercially processed foods:
Ö Purchase date(s).
Ö Product descriptions.
•
Medical history related to outbreak to verify the diagnosis.
− Signs, symptoms, duration.
Duration of symptoms typically longer for bacterial than viral.
Need to define diarrhea: >3 loose stools in a 24 hour period is a well
accepted standard.
− Medical care/diagnostics
Who did they see?
Were they given a diagnosis? If so, what was the diagnosis?
Were stool samples collected? Other specimens?
− Availability of food or clinical samples (e.g., did diners take food home?)
− Potential for non-foodborne routes of transmission (remember last meal bias).
Travel
Pets or other animal contact
Water (drinking or recreational)
Illnesses in household or other close contacts (possible person-to-person
transmission)
Other
− Open-ended questions
Can be time consuming.
Allow person to respond in multiple words.
Encourage person to use own words to tell their story.
May be more difficult to analyze statistically than yes-no questions.
Typically used for initial interviewing before many specifics are known.
APPENDIX 3
− Closed-ended questions
Closed-ended questions usually have just one answer option.
Typically used to gather specific information that can be used for casedefinitions, hypothesis development and testing.
Potentially restrictive and leading.
Example: "Did you eat the chicken salad? “
Can be used if a response to an open-ended question does not address
what the issue (fill in any voids).
Example: "What were the foods that you ate?" Then follow up with: "Did
you consume any other foods or drinks?"
− Obtain list of foods served by caterer or restaurant.
Cannot rely on the individual’s memory alone.
Get a list of the items served.
− Generic Forms
Typically used for small outbreaks or early in an investigation before
specifics are known.
Different generic forms are used by various disciplines at present
Ö Routine unconfirmed illnesses: complete IAMFES Form C 1-2 recommended for use by Environmental Health.
Ö Routine laboratory confirmed infections: MDCH Enteric Illness Report required for use by communicable disease staff to report to MDCH.
− Use of same forms throughout the entire investigation increases consistency.
− Customized outbreak questionnaires
Consult an epidemiologist or experienced investigator to ensure questions
are unbiased.
Avoid leading questions or "double barrel" questions which are difficult to
answer with a yes or no response.
Example: "Did you clean and sanitize the cutting board?" has two parts;
“Did you clean it?” and “Did you sanitize it?”

Advantages of using a structured questionnaire:
Ö Identifies more specifically the information to be gathered, increasing
consistency and completeness.
Ö Decreases number of follow up contacts to fill in data gaps.
Ö Development of questionnaire by team members builds consensus
regarding what information is important.
Ö How the questions are asked and the order of questions can affect the
answers.
APPENDIX 3
− Hints on food history questions
Assess the individual’s ability to recall food consumption
Ö Persons with excellent memories can provide important clues
People may not remember fast food meals (example: drive through) as
well as meals consumed at sit-down restaurants.
Persons who work as food handlers may not have eaten meals at their
place of work, but still may have consumed foods from work.
Obtaining a menu or accurate list of the items served is important, as it will
aid in assisting persons remember accurately what they consumed.
Ö Misclassification bias results when investigators inaccurately assess
which foods were consumed, resulting in failure to detect a valid
association between illness and consumption of a particular food.
Word questions differently for weddings/buffets vs. restaurants.
Ö Restaurants - People typically remember what they ordered.
Ö Buffets – Food items generally not labeled and questions need to
clearly describe each food (importance of obtaining a complete list of
all foods served).
Have an “other food” category on questionnaires. Allows respondents to
indicate consumption of a food not previously known to have been served;
Ö Check master food list (menu) to verify that it is complete and
accurate.
Ö Ask clarifying questions to ensure that they are not using a different
name for a food on the list (e.g., crab salad and macaroni salad may
be the same).
Recognize the potential for “last meal bias” which is difficult to rule out
when investigating isolated incidents.
Identifying food preferences can be helpful when individual is not certain
what they ate (e.g., individuals state they definitely would not have eaten
buffet items containing pineapple).
Ö Assess probability that foods were consumed (definite, probable,
possible, definitely not).
Ö Have individual identify what they typically would eat for the meal (e.g.,
cereal or bagel for breakfast).
Ö Identifying food categories that they would likely eat or definitely would
not eat can provide important clues to help rule in or rule out
consumption of certain foods.
It may sometimes be appropriate to ask where people sat at an event or
their place in line at a buffet style party.
Ö Assess person-to-person transmission at a “sick table”.
APPENDIX 3

Assign and prepare staff who will be interviewing
•
Minimize roadblocks to effective two-way communication;
− Noise and distractions,
− Lack of trust,
− Fear of losing job,
− Not in persons interest to communicate the truth, and
− Reluctance to incriminate self or a friend.
•
Review characteristics of effective interviewer (as needed) to create an
atmosphere that is:
−
−
−
−
•
Non judgmental
Objective
Sympathetic (strives to maintain confidentiality)
Fair
An interview is a directed and purposeful "conversation" requiring good
communication skills including;
− Listening - Interpreting what is said correctly, and
− Observation - Picking up on nonverbal cues.
•
Assign adequate numbers of interviewers and arrange work schedules to allow
interviewing at times most likely to yield the best results:
− Make it convenient for the person you're interviewing (interviewing is not 9-5
business).
− Remember that the public is not obligated to communicate with you.
− Maintain good will so individuals are willing to cooperate.
− Balance quality of information gathered vs. quantity of interviews that must be
completed.
•
When conducting face-to-face interviews;
− Maintain eye contact.
− Being sensitive to "signals" that may indicate stress or uneasiness.
Body language,
Failure to make eye contact,
Signs of stress in the voice, and
Pauses and inconsistent information.
APPENDIX 3
− Adjust your approach and try to regain a comfort level with the person.
Allow for differences in personal interviewing styles. Individuality itself is
not a problem.
Ö Some people naturally come on strong.
Ö Others are more passive.
Ö Do not let style effect objectivity.
Be aware of preconceived opinions and your own bias.
Maintain an unhurried pace during the interview. Too direct and rushed
questioning may be interpreted as “the third degree”.
Focus on the person being interviewed. Seek to understand:
Ö Where other people are coming from,
Ö How they might react, and
Ö What's at stake for them.
•
Obtain information about disease causing organisms from a current text (see
listed references for examples).
•
Familiarize all interviewers with the questionnaire that will be used.
− Reach agreement on format and content.
− Go over with the entire group of interviewers.
− Pilot testing is recommended.
•
“Recall bias” a significant factor to overcome. Tips to increase accuracy of recall:
− Jog their memory by asking them to think what else they were doing during
the time period.
− Be prepared with days and dates from that time period (e.g., community
events, holidays, school vacations).
− Using a calendar to map out individual's activities may be helpful.
•
Identify appropriate site(s) for interviews. This can help you get a more accurate
picture of what happened.
− Think about the person's feelings.
− Avoid distractions.
− Privacy
Prefer not to tell the world about the diarrhea
Self-incrimination (avoid interviewing food workers with their supervisors
present).
APPENDIX 3
B. During Interviews

•
People do not care how much you know until they know how much you care.
•
Emphasize that their cooperation will help find the cause(s) of the outbreak and
prevent others from becoming ill.
•
Inform them that investigators may need to re-interview them at different points in
the investigation to gather additional information.
− The focus of questions may change.
− Need to confirm or clarify information already provided.
•
Ask at the beginning “Is this a convenient time for you”? If not, reschedule.
•
Be punctual, keeping appointments as promised.
•
Begin interviews by letting people know;
−
−
−
−
Who you are (name and title),
Who you work for,
Your purpose, and
Why you need their cooperation.
Example: "There've been reports of possible foodborne illness and I’m
investigating to find out what happened."
− How long the interview will take.
•
Practice effective listening skills.
− Consider repeating the question and answer to be sure you both agree on
what was said.
− Avoid leading people to provide answers they believe you want to hear
Example: “You didn’t happen to eat the alfalfa sprouts did you?”
•
Assess the persons communication style:
−
−
−
−
Action: Bottom-line “just the facts”.
Feeling: In touch with their emotions and relationships.
Creative: Needs to see the “big picture” and how everything ties in together.
Thinking: Loves the details.
APPENDIX 3
•
Inform individuals up front that multiple contacts may be necessary and the focus
of the questions may change.
•
Ease into the interview by starting with a few directed questions like:
− What is your name?
− Your address?
− Occupation?

•
Be open and honest without divulging confidential information.
•
Refer questions regarding medical care to a nurse or health-care provider.
Ask questions as written if closed-ended questionnaire is being used.
•
Make sure to ask questions in the order listed on the questionnaire.
•
Questions asked in inconsistent order may collect inaccurate information.
Example: Make sure to ask these questions in the following order if
interested in determining the duration of illness:
−
−
−
−
“Were you ill?
What were your symptoms?
Are you still having symptoms?
What symptoms are you still having?”

Review form before completing interview to ensure fully complete.

•
Questionnaires may not contain all the appropriate questions.
•
Involved persons may have information that investigators have not previously
considered.
•
Share noteworthy or unusual findings with the team leader immediately.
If for some reason you can't complete the interview:
•
Make another appointment.
•
Provide your name and phone number (leave card).
•
Allow people to call you from the security of their own home.
APPENDIX 3

•
Invite the person to contact you if they think of anything else.
•
Thank them for their time.
C. After the Interview

Turn in questionnaires to be reviewed (quality control).
•
This allows for early identification of inconsistencies in:
− Interviewing methods.
− Problems with questionnaire design (example: inaccurate list of foods
served).

Enter information into database as soon as possible.
•
This allows for timely:
− Refinement of case-definitions and working hypotheses, and
− Implementation of control actions.

Keep track of who has been interviewed and who is interviewing.
•
Avoid duplication.
A master list is important – especially if different agencies are involved.
APPENDIX 4
Complaint Number:
Establishment Name
Address
Date & Time of Suspect Meal
Phone Number _________________
:
am pm (circle)
/
mo day
Date & Time Food Preparation Started
yr
/
mo
day
:
am pm (circle)
yr
Person Interviewed: Name
Position Held: ________________
Review Conducted:
Observing Preparation
Interviewing person who made
original food
Other (specify) ________________________
Suspect Food ________________________
DATE
PROCESS
OBSERVATION
AMOUNT
OF
FOOD
TIME OF
DAY
TEMP
OF
FOOD
EQUIPMENT
USED
DEPTH OF
CONTAINER
OR FOOD
THICKNESS
HAND
CONTACT
WITH
FOOD
WORKER’S
NAME
WORKE
R
HEALTH
PRIOR
TO
FOOD
PREP
Y
Ill
N
Well
Y
Ill
N
Well
Y
Ill
N
Well
Y
Ill
N
Well
Y
Ill
N
Well
Y
Ill
N
Well
Y
Ill
N
Well
Y
Ill
N
Well
SANITATIO
N UNUSUAL
EVENTS
OTHER
INFORMATI
ON
APPENDIX 4
APPENDIX 4
Form approved OMB No. 0920-0004
Electronic
Foodborne
Outbreak
Reporting
System
Investigation of a Foodborne Outbreak
This form is used to report foodborne disease outbreak investigations to CDC. It is also
used to report Salmonella Enteritidis and E. coli O157:H7 outbreak investigations
involving any mode of transmission. A foodborne outbreak is defined as the occurrence
of two or more cases of a similar illness resulting from the ingestion of a common food
in the United States. This form has 6 parts. Part 1 asks for the minimum or basic
information needed and must be completed for the investigation to be counted in the
CDC annual summary. Part 2 asks for additional information for any foodborne
outbreak, while Parts 3 – 6 ask for information concerning specific vehicles or
etiologies. Please complete as much of all parts as possible.
CDC Use Only
__-___________
State Use Only
______________
Part 1: Basic Information
1. Report Type
A.
□ Please check if this a final report
3. Dates
Please enter as many dates as possible
Date first case became ill __ __/__ __/__ __ __ __
Month
B.
□ Please check if data does not support a
FOODBORNE outbreak
Day
Year
Date last case became ill __ __/__ __/__ __ __ __
Month
Day
Year
Date first known exposure __ __/__ __/__ __ ____
Month
2. Number of Cases
Day
Year
Date last known exposure __ __/__ __/__ __ __ __
Month
Day
Year
Lab-confirmed cases______(A)
Including _______ secondary cases
Estimated total ill__________
(If greater than sum A + B)
<1 year _____% 20-49 yrs _____%
1-4 yrs _____% ≥50 yrs _____%
5-19 yrs ____% Unknown _____%
Reporting state ________________
If multiple states involved:
□ Exposure occurred in multiple states
□ Exposure occurred in single state, but cases
resided in multiple states
Other states: __________________
_____________________________
_____________________________
Reporting county_______________
If multiple counties involved:
□ Exposure occurred in multiple counties
□ Exposure occurred in one county, but cases
resided in multiple counties
Other counties: ________________
_____________________________
_____________________________
Probable cases______(B)
Including _______ secondary cases
5. Approximate Percentage of
Cases in Each Age Group
4. Location of Exposure
6. Sex
7. Investigation Methods (Check all that apply)
(Estimated percent of
the total cases)
□ Interviews of only cases
□ Food preparation review
□ Investigation at factory or production plant
□ Investigation at original source
Male___________%
Female___________%
□ Case-control study
□ Cohort study
(farm, marine estuary, etc.)
□ Food product traceback
□ Environment / food sample cultures
8. Implicated Food(s): (Please provide known information)
Name of Food
e.g., Lasagna
Main Ingredient(s) Contaminated Ingredient(s)
e.g., Pasta, sauce,
eggs, beef
e.g., Eggs
Reason(s) Suspected
(See codes just below)
e.g., 4
Method of Preparation
(See attached codes)
e.g., M1
1)
2)
3)
□ Food vehicle undetermined
Reason Suspected (List above all that apply)
1 - Statistical evidence from epidemiological investigation
2 - Laboratory evidence (e.g., identification of agent in food)
3 - Compelling supportive information
4 - Other data (e.g., same phage type found on farm that supplied eggs)
5 - Specific evidence lacking but prior experience makes it likely source
CDC 52.13 revised November, 2004
Public reporting burden of this collection of information is estimated to average 20 minutes per response, including the time for reviewing
instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of
information. An agency may not conduct or sponsor, and a person is not required to respond to a collection of information unless it displays
a currently valid OMB control number. Send comments regarding this burden estimate or any other aspect of this collection of information,
including suggestions for reducing this burden to CDC/ATSDR Reports Clearance Officer; 1600 Clifton Road NE, MS D-74, Atlanta,
Georgia 30333; ATTN: PRA (0920-0004).
APPENDIX 4
9. Etiology: (Name the bacteria, virus, parasite, or toxin. If available, include the serotype and other characteristics such as phage type, virulence
factors, and metabolic profile. Confirmation criteria available at http://www.cdc.gov/foodborneoutbreaks/guide_fd.htm or MMWR2000/Vol. 49/SS1/App. B)
Etiology
Serotype
1)
Other Characteristics
(e.g., phage type)
Detected In
(See codes just below)
□ Confirmed
□ Confirmed
□ Confirmed
2)
3)
□ Etiology undetermined
Detected In (List above all that apply)
1 - Patient Specimen(s)
2 - Food Specimen(s)
3 -Environment specimen(s)
4 - Food Worker specimen(s)
10. Isolate Subtype
State Lab ID
PFGE (PulseNet designation)
PFGE (PulseNet designation)
1)
2)
3)
11. Contributing Factors (Check all that apply. See attached codes and explanations)
□ Contributing factors unknown
Contamination Factor
□C1 □C2 □C3 □C4 □C5 □C6 □C7 □C8 □C9 □C10 □C11 □C12 □C13 □C14 □C15 (describe in Comments) □ N/A
Proliferation/Amplification Factor (bacterial outbreaks only)
□P1 □P2 □P3 □P4 □P5 □P6 □P7 □P8 □P9 □P10 □P11 □P12 (describe in Comments) □ N/A
Survival Factor (microbial outbreaks only)
□S1 □S2 □S3 □S4 □S5 (describe in Comments) □N/A
□ Was food-worker implicated as the source of contamination? □ Yes □ No
If yes, please check only one of following
□ laboratory and epidemiologic evidence
□ epidemiologic evidence (w/o lab confirmation)
□ lab evidence (w/o epidemiologic evidence)
□ prior experience makes this the likely source (please explain in Comments)
APPENDIX 4
Part 2: Additional Information
12. Symptoms, Signs and Outcomes
Cases with
Total cases for whom
Feature
outcome/
feature
you have information
available
Healthcare provider
visit
Hospitalization
Death
13. Incubation Period
(Circle appropriate units)
Shortest______(Hours, Days)
Longest______(Hours, Days)
Median ______(Hours, Days)
□ Unknown
Vomiting
14. Duration of Illness
(Among those who recovered)
(Circle appropriate units)
Shortest______(Hours, Days)
Longest______(Hours, Days)
Median ______(Hours, Days)
□ Unknown
Diarrhea
Bloody stools
∗ Use the following terms, if appropriate, to describe other common
Fever
characteristics of cases
Abdominal cramps
Anaphylaxis
Arthralgia
Bradycardia
Bullous skin lesions
Coma
Cough
Descending paralysis
Diplopia
Flushing
HUS or TTP
Asymptomatic
*
*
*
Headache
Hypotension
Itching
Jaundice
Lethargy
Myalgia
Paresthesia
Septicemia
Sore throat
Tachycardia
Temperature reversal
Thrombocytopenia
Urticaria
Wheezing
15. If Cohort Investigation Conducted:
Attack rate* = __________/ __________________________________ x 100 = ________%
Exposed and ill
Total number exposed for whom you have illness information
* The attack rate is applied to persons in a cohort who were exposed to the implicated vehicle. The numerator is the number of persons who were exposed and became ill;
the denominator is the total number of persons exposed to the implicated vehicle. If the vehicle is unknown, then the attack rate should not be calculated.
16. Location Where Food Was Prepared
17. Location of Exposure or Where Food Was Eaten
(Check all that apply)
□Restaurant or deli
□ Nursing home
□ Day care center
□ Prison, jail
□ School
□ Private home
□ Office setting
□ Workplace, not cafeteria
□ Workplace cafeteria
□ Wedding reception
□ Banquet Facility
□ Church, temple, etc
□ Picnic
□ Camp
□ Caterer
□ Contaminated food imported into U.S.
□ Grocery Store
□ Hospital
□ Fair, festival, other temporary/ mobile services
□ Commercial product, served without further preparation
□ Unknown or undetermined
□ Other (Describe) ________________________________
(Check all that apply)
□ Restaurant or deli
□ Nursing Home
□ Day care center
□ Prison, jail
□ School
□ Private home
□ Office Setting
□ Workplace, not cafeteria
□ Workplace cafeteria
□ Wedding Reception
□ Banquet Facility
□ Church, temple, etc.
□ Picnic
□ Camp
□ Grocery Store
□ Hospital
□ Fair, festival, temporary/ mobile service
□ Unknown or undetermined
□ Other (Describe) _____________________________________
18. Trace back
□ Please check if trace back conducted
Source to which trace back led:
Source
(e.g., Chicken farm, Tomato processing plant)
Location of Source
State
Comments
Country
APPENDIX 4
19. Recall
□ Please check if any food product recalled
Recall Comments
__________________________________________________________
__________________________________________________________
__________________________________________________________
__________________________________________________________
__________________________________________________________
20. Available Reports (Please attach)
□ Unpublished agency report
□ Epi-Aid report
□ Publication (please reference if not attached)
__________________________________________________________
__________________________________________________________
21. Agency reporting this outbreak
___________________________________________
22. Remarks
Contact person:
Name _____________________________________
Title ______________________________________
Phone _____________________________________
Fax _______________________________________
E-mail ____________________________________
________________________________________________________
Briefly describe important aspects of the outbreak not covered above
(e.g., restaurant closure, immunoglobin administration, economic impact, etc)
____________________________________________
____________________________________________
____________________________________________
____________________________________________
Part 3: School Questions
1. Did the outbreak involve a single or multiple schools?
□ Single
□ Multiple (If yes, number of schools____)
2. School characteristics (for all involved students in all involved schools)
a. Total approximate enrollment
_____ (number of students)
□ Unknown or Undetermined
b. Grade level(s) (Please check all grades affected)
□ Preschool
□ Grade School (grades K-12)
Please check all grades affected: □K □1st
□ College/University/Technical School
□2nd □3rd □4th □5th □6th □7th □8th □9th □10th □11th □12th
c. Primary funding of involved school(s)
□ Public □ Private □ Unknown or Undetermined
3. Describe the preparation of the implicated
item:
□ Heat and serve (item mostly prepared or cooked
off-site, reheated on-site)
□ Served a-la-carte
□ Serve only (preheated or served cold)
□ Cooked on site using primary ingredients
□ Provided by a food service management company
□ Provided by a fast food vendor
□ Provided by a pre-plate company
□ Part of a club/ fundraising event
□ Made in the classroom
□ Brought by a student/teacher/parent
□ Other ___________________
4. How many times has the state, county or local health
department inspected this school cafeteria or kitchen in the
12 months before the outbreak?*
□ Once
□ Twice
□ More than two times
□ Not inspected
5. Does the school have a HACCP plan in place for the
school feeding program?*
□ Yes
□ No
*If there are multiple schools involved, please answer according to the most
affected school
APPENDIX 4
6. Was implicated food item provided to the
school through the National School
Lunch/Breakfast Program?
□ Yes
□ No
If Yes, Was the implicated food item donated/purchased
by :
□ USDA through the Commodity Distribution Program
□ Purchased commercially by the state/school authority
□ Other_____________________________
Part 4: Ground Beef
1. What percentage of ill persons (for whom information is available) ate ground beef raw or undercooked? _____%
2. Was ground beef case ready? (Ground beef that comes from a manufacturer packaged for sale and not altered or repackaged by the retailer)
□ Yes
□ No
3. Was the beef ground or reground by the retailer?
□ Yes
□ No
If yes, was anything added to the beef during grinding (e.g., shop trim or any product to alter the fat
content)____________________________________________________________________________
Part 5: Mode of Transmission
(Enterohemorrhagic E. coli or Salmonella Enteritidis only)
1. Mode of Transmission (for greater than 50% of cases)
Select one:
□ Food
□ Person to person
□ Swimming or recreational water
□ Drinking water
□ Contact with animals or their environment
Part 6: Additional Egg Questions
1. Were Eggs: (Check all that apply)
□ in-shell, un-pasteurized?
□ in-shell, pasteurized?
□ liquid or dry egg product?
□ stored with inadequate refrigeration during or after sale?
□ consumed raw?
□ consumed undercooked?
□ pooled?
2. If eggs traced back to farm, was Salmonella Enteritidis found on the farm?
□ Yes
□ No
Comment:_____________________________________________________________________________________________
_____________________________________________________________________________________________
APPENDIX 4
Contamination Factors:1
C1 - Toxic substance part of tissue (e.g., ciguatera)
C2 - Poisonous substance intentionally added (e.g., cyanide or phenolphthalein added to cause illness)
C3 - Poisonous or physical substance accidentally/incidentally added (e.g., sanitizer or cleaning compound)
C4 - Addition of excessive quantities of ingredients that are toxic under these situations (e.g., niacin poisoning in bread)
C5 - Toxic container or pipelines (e.g., galvanized containers with acid food, copper pipe with carbonated beverages)
C6 - Raw product/ingredient contaminated by pathogens from animal or environment (e.g., Salmonella Enteriditis in
egg, Norwalk in shellfish, E. coli in sprouts)
C7 - Ingestion of contaminated raw products (e.g., raw shellfish, produce, eggs)
C8 - Obtaining foods from polluted sources (e.g., shellfish)
C9 - Cross-contamination from raw ingredient of animal origin (e.g., raw poultry on the cutting board)
C10 - Bare-handed contact by handler/worker/preparer (e.g., with ready-to-eat food)
C11 - Glove-handed contact by handler/worker/preparer (e.g., with ready-to-eat food)
C12 - Handling by an infected person or carrier of pathogen (e.g., Staphylococcus, Salmonella, Norwalk agent)
C13 - Inadequate cleaning of processing/preparation equipment/utensils B leads to contamination of vehicle (e.g.,
cutting boards)
C14 - Storage in contaminated environment B leads to contamination of vehicle (e.g., store room, refrigerator)
C15 - Other source of contamination (please describe in Comments)
Proliferation/Amplification Factors:
1
P1 - Allowing foods to remain at room or warm outdoor temperature for several hours (e.g., during preparation or
holding for service)
P2 - Slow cooling (e.g., deep containers or large roasts)
P3 - Inadequate cold-holding temperatures (e.g., refrigerator inadequate/not working, iced holding inadequate)
P4 - Preparing foods a half day or more before serving (e.g., banquet preparation a day in advance)
P5 - Prolonged cold storage for several weeks (e.g., permits slow growth of psychrophilic pathogens)
P6 - Insufficient time and/or temperature during hot holding (e.g., malfunctioning equipment, too large a mass of food)
P7 - Insufficient acidification (e.g., home canned foods)
P8 - Insufficiently low water activity (e.g., smoked/salted fish)
P9 - Inadequate thawing of frozen products (e.g., room thawing)
P10 - Anaerobic packaging/Modified atmosphere (e.g., vacuum packed fish, salad in gas flushed bag)
P11 - Inadequate fermentation (e.g., processed meat, cheese)
P12 - Other situations that promote or allow microbial growth or toxic production (please describe in Comments)
Survival Factors:1
S1 - Insufficient time and/or temperature during initial cooking/heat processing (e.g., roasted meats/poultry, canned
foods, pasteurization)
S2 - Insufficient time and/or temperature during reheating (e.g., sauces, roasts)
S3 - Inadequate acidification (e.g., mayonnaise, tomatoes canned)
S4 - Insufficient thawing, followed by insufficient cooking (e.g., frozen turkey)
S5 - Other process failures that permit the agent to survive (please describe in Comments)
Method of Preparation:2
M1 - Foods eaten raw or lightly cooked (e.g., hard shell clams, sunny side up eggs)
M2 - Solid masses of potentially hazardous foods (e.g., casseroles, lasagna, stuffing)
M3 - Multiple foods (e.g., smorgasbord, buffet)
M4 - Cook/serve foods (e.g., steak, fish fillet)
M5 - Natural toxicant (e.g., poisonous mushrooms, paralytic shellfish poisoning)
M6 - Roasted meat/poultry (e.g., roast beef, roast turkey)
M7 - Salads prepared with one or more cooked ingredients (e.g., macaroni, potato, tuna)
M8 - Liquid or semi-solid mixtures of potentially hazardous foods (e.g., gravy, chili, sauce)
M9 - Chemical contamination (e.g., heavy metal, pesticide)
M10 - Baked goods (e.g., pies, éclairs)
M11 - Commercially processed foods (e.g., canned fruits and vegetables, ice cream)
M12 - Sandwiches (e.g., hot dog, hamburger, Monte Cristo)
M13 - Beverages (e.g., carbonated and non-carbonated, milk)
M14 - Salads with raw ingredients (e.g., green salad, fruit salad)
M15 - Other, does not fit into above categories (please describe in Comments)
M16 - Unknown, vehicle was not identified
1
Frank L. Bryan, John J. Guzewich, and Ewen C. D. Todd. Surveillance of Foodborne Disease III.
Summary and Presentation of Data on Vehicles and Contributory Factors; Their Value and Limitations.
Journal of Food Protection, 60; 6:701-714, 1997.
2
Weingold, S. E., Guzewich JJ, and Fudala JK. Use of foodborne disease data for HACCP risk
assessment. Journal of Food Protection, 57; 9:820-830, 1994.
APPENDIX 4
APPENDIX 4
APPENDIX 4
APPENDIX 4
APPENDIX 5
WEB-BASED RESOURCES TO EXPLORE
Epidemiologic Case Studies, www.phppo.cdc.gov/phtn/casestudies
These case studies are interactive exercises developed to teach epidemiologic principles and practices.
They are based on real-life outbreaks and public health problems and were developed in collaboration with
the original investigators and experts from the Centers for Disease Control and Prevention. The case
studies require students to apply their epidemiologic knowledge and skills to problems confronted by
public health practitioners at the local, state, and national level every day.
Two types of epidemiologic case studies are available. The computer-based case studies can be used as a
self-study and in the classroom setting. The classroom case studies are primarily for use in a group setting
with a knowledgeable instructor. Instructor Guides are available on-line.
Principles of Epidemiology, www.phppo.cdc.gov/PHTN/catalog/305g.asp
This is a print-based self study course available to download as PDF’s or as a textbook you can order from
the Public Health Foundation. This text serves as an excellent reference tool for the application of
epidemiology and biostatistics.
Bioterrorist Attack on Food: A Tabletop Exercise,
http://healthlinks.washington.edu/nwcphp/edu/phe/
This learning exercise is an opportunity for public health personnel and their local emergency counterparts
to gain skills and knowledge in preparing for and responding to a large-scale communicable disease
outbreak or bioterrorism event.
Epi Info™ – Centers for Disease Control and Prevention, www.cdc.gov/epiinfo/
With Epi Info™ and a personal computer, epidemiologists and other public health and medical
professionals can rapidly develop a questionnaire or form, customize the data entry process, and enter and
analyze data. Epidemiologic statistics, tables, graphs, and maps are produced with simple commands such
as READ, FREQ, LIST, TABLES, GRAPH, and MAP. Epi Map displays geographic maps with data from
Epi Info™.
NEHA Training, www.nehatraining.com is the Regulator’s Choice™ for food safety education and
training. Their materials and publications provide some of the best defenses for taking a proactive
approach to preventing outbreaks before they occur. Their books contain all essential microbiological and
technical food safety principles in ways that are easy to read, understand, and retain. In addition, NEHA
Training registers qualified food safety trainers and provides them with the support and resources they
need to deliver effective training. For more information about their books or training resources visit
www.nehatraining.com or call 303-756-9090 x340.
Investigating an Outbreak: Pharyngitis in Louisiana, www.phppo.cdc.gov/PHTN/catalog/303g.asp
Fun interactive simulation where you conduct the outbreak investigation to determine the source and
control measures to undertake. This product is DOS-based…an antique that is compatible with Windows!
“E. coli O157:H7 Infection in Michigan” and “Botulism in Argentina” Computer-based Case
Studies, http://www.phppo.cdc.gov/phtn/casestudies/
The Centers for Disease Control and Prevention recommend this computer-based case study, “E. coli
O157:H7 Infection in Michigan”. Based on a real-life outbreak investigation by Dr. Thomas Breuer and
colleagues in 1997, this self-instructional, interactive exercise teaches epidemiologic skills in outbreak
investigation and allows students to apply and practice those skills.
APPENDIX 5
UNC’s John Snow Case Study, www.sph.unc.edu/courses/john_snow/
This is a short engaging case study that walks you through the classic John Snow investigation. It sets the
foundation for epidemiology and public health.
Outbreak Investigation Toolkit, www.cdc.gov/foodborneoutbreaks
This site has been established to provide public health officials, researchers, and the general public with
information on foodborne disease outbreaks. The toolkit includes:
•
•
Standard
Questionnaire
Specimen Collection
Guide
•
•
Confirmation Criteria
for Foodborne
Outbreak Etiologies
Atlas of Food
Consumption
•
•
PHLIS (Public Health
Laboratory
Information System)
and more!
CDC Resources for Local Health Departments,
http://www.phppo.cdc.gov/dphsdr/localhealth/index.asp
This site is intended as a resource for Local Health Department personnel to gain easy access to CDC's
public health practice materials and information.
Johns Hopkins Bloomberg School of Public Health, http://ocw.jhsph.edu
The Johns Hopkins Bloomberg School of Public Health's OPENCOURSEWARE (OCW) project
provides access to content of the School's most popular courses. As challenges to the world's health
escalate daily, the School feels a moral imperative to provide equal and open access to information and
knowledge about the obstacles to the public's health and their potential solutions.
CDC Form 52.13/EFORS/Spoon and Fork,
http://www.cdc.gov/mmwr/preview/mmwrhtml/ss5510a2.htm?s_cid=ss5510a2_e
APPENDIX 6
ANSWERS
Graduation Party Blues
Food Preparation Review
1. Using the information provided, complete a food preparation flow diagram for one of the
following foods: meatballs, spaghetti sauce, rigatoni, chef salad, fried chicken, potato salad,
pea salad and fruit salad.
Peel
potatoes
Boil potatoes
Drain water
to allow
cooling
To reach-in
for cooling
Boil eggs
Drain water,
to refrigerator
to cool
Peel, chop
Refrigerate
in shallow
pan
Chop celery,
onions, and
green peppers
potato
salad
Mix cold
ingredients
Cold store
in hotel
pans
Transport
Serve
1
APPENDIX 6
2. Complete the food preparation review for the fruit salad with the attached form.
Complaint Number: 111
Establishment Name _____Sanborne Home____________
Address
Phone Number __555-1212
Date & Time of Suspect Meal 0 6 2 9 0 0 / 1 3 : 0
Mo. day yr.
Date & Time Food Preparation Started 0 6 2 8 0 0 / 1
mo day yr.
Person Interviewed Name
Tilly Olson
Review Conducted: _____Sanitarian name
0 am PM (circle)
6 : 0
0 am PM (circle)
Position Held: Food Preparer
Other (specify) __________________________________
Suspect Food Fruit Salad
DATE
PROCESS
OBSERVATION
AMOUNT
OF
FOOD
TIME
OF
DAY
TEMP
OF FOOD
EQUIPMENT
USED
DEPTH OF
CONTAINER
OR FOOD
THICKNESS
6/28
Cut up fruits and
place them in
watermelon
halves
Unknown
4 PM
None
taken
Knife, cutting
board
Watermelon
halves
HAND
CONTACT
WITH FOOD
Y
N
2
WORKER’S
NAME
Tilly
WORKER
HEALTH
PRIOR TO
FOOD
PREP
Ill
Well
SANITATION
UNUSUAL
EVENTS
OTHER
INFORMATION
Tilly was ill with
GI symptoms. She
did not properly
wash her hands
after using the
toilet. She used
bare hands to cut
up fruit and
remove seeds.
APPENDIX 6
Answer Sheet
Questions:
1. What type of a study would you perform in order to determine which food caused the
illness? Why?
Cohort- there is a well-defined population and all of the participants can be identified.
2. What is the attack rate of people who ate turkey that developed vomiting? Diarrhea?
Fever?
Vomiting: 7/10 or .7
A total of 10 people ate turkey and of those people, 7 became ill with vomiting.
Diarrhea: 8/10 or .8
A total of 10 people ate turkey and of those people, 8 became ill with diarrhea.
Fever: 5/10 or .5
A total of 10 people ate turkey and of those people, 5 became ill with fever.
3. Fill in the 2x2 table for people who ate pie and became ill.
Disease
Exposure
Yes
Yes
No
4
4
5
2
to
Pie
No
APPENDIX 6
4. Fill in the 2x2 table for people who ate turkey and became ill.
Disease
Exposure
to
turkey
Yes
No
Yes
No
8
2
1
4
5. Calculate the relative risk for developing disease if a person ate pie. What does this
value mean?
RR= a/(a+b)
c/(c+d)
4/(4+4) = .5 = .7
5/(5+2)
.714
The risk for developing disease given exposure to pie is less than the risk for developing
disease without exposure to pie (RR=.714). Therefore, people who ate pie were actually
protected from disease.
6. Calculate the relative risk for developing disease if a person ate turkey. What does this
value mean?
RR= a/(a+b)
c/(c+d)
8/(8+2) =
1/(1+4)
.8 = 4
.2
The risk for developing disease given exposure to turkey is more than the risk for developing
disease without exposure to turkey (RR=4). Therefore, people who ate turkey were four
times more likely to develop disease than those who did not.
7. Which food item was more likely to cause illness- the turkey or the pie? Why?
Turkey- People who ate turkey were 4 times more at risk for developing the disease. The
people who ate pie were protected from disease because their risk of developing illness is
less than one.
8. The p-value for the relative risk estimate for turkey consumption is p= .03. What does
this mean? What if the p-value was p= .65?
A p-value of .03 indicates that we can have a high level of confidence that our four fold estimate
of increased risk associated with turkey consumption is very unlikely to be due to chance alone.
We are 97% certain that our estimate of 4.0 is not really 1.0 (our 97% confidence interval does
not include 1.0). If the p-value = .65 there would be a 35% chance that the RR could actually be
1.0. Therefore, given such a high p-value, we cannot say that our results are statistically
significant due to chance alone.