Foodborne Disease Outbreak
Investigation Team Training:
Module 1 – Foodborne
Diseases and Outbreaks
Foodborne diseases and outbreaks
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Module Learning Objectives
At the end of this module, you will be able to
1. Describe what is meant by “foodborne
disease.”
2. List examples of common foodborne disease
causative agents.
3. Define the terms “outbreak” and “cluster.”
4. List the goals of a foodborne disease outbreak
investigation.
5. Describe the desirable knowledge and skills
included on a foodborne outbreak investigation
team.
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BREAKING NEWS
• Students and teachers
rushed to hospital
• Nausea, vomiting,
stomach pain, and
dizziness after lunch
at school cafeteria
• Health department
team dispatched to
school and hospital to
investigate
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Group Discussion
Divide into groups by table.
1. Briefly introduce yourself to others at your table.
2. Re-read the news report at end of module and
answer these questions.
• Do you think the illnesses are foodborne?
• Do you think the illnesses represent an
outbreak?
• If this is a foodborne outbreak, who would you
involve in the investigation?
Be prepared to share your
thoughts with the class.
Time limit: 5 minutes
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Foodborne Disease
• Illness caused by ingestion of contaminated food
• Symptoms often affecting stomach or intestinal
tract including
– Nausea and vomiting
– Diarrhea
– Abdominal pain
• Sometimes nonspecific symptoms and symptoms
outside GI tract, depending on agent
• Young children, pregnant women, elderly, and
immunocompromised persons at greatest risk for
severe illness
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Foodborne Disease
• An estimated 1 in 6 people suffers from
foodborne illness each year in the United
States leading to an estimated
– 48 million illnesses
– 128,000 hospitalizations
– 3,000 deaths
• More than 1,000 outbreaks detected annually
• $35 billion in medical costs, lost productivity,
illness related mortality each year
Source: Centers for Disease Control and Prevention
http://www.cdc.gov/foodborneburden/index.html
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Common Causative Agents
Bacteria
Bacillus cereus
Campylobacter
Clostridium botulinum
Clostridium perfringens
Escherichia coli
Shiga toxin-producing E. coli
Enterotoxin producing E. coli
Enteroinvasive E. coli
Enteropathogenic E. coli
Listeria monocytogenes
Salmonella, non-typhoid
Salmonella Typhi
Shigella
Staphylococcus aureus
Vibrio
Yersinia enterocolitica
Foodborne diseases and outbreaks
Viruses
Norovirus
Astrovirus
Hepatitis A virus
Parasites
Cryptosporidium
Cyclospora cayetanensis
Entamoeba histolytica
Giardia intestinalis
Trichinella
Chemicals/other
Heavy metals
Pesticides
Fungal toxins
Fish toxins
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
Frequency of Causative Agents in
Foodborne Outbreaks in the United States
Bacteria (40%)
Salmonella (18%)
Clostridium
perfringens (6%)
STEC (5%)
Campylobacter (4%)
Viruses (54%)
Norovirus
Chemicals/other (5%)
Parasites (<1%)
Foodborne diseases and outbreaks
Source: Centers for Disease
Control and Prevention
based on data from 2008
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Food Vehicles
• Variety of foods associated with foodborne
illnesses
• Almost any food can be a vehicle for disease
but food and production/processing must
– Allow opportunity for contamination by
causative agent
– Allow agent (or toxin) to survive (not be
inactivated) and
– (For some agents) support proliferation of
agent and/or elaboration of preformed toxins
• Common food-causative agent pairings
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… Also Other Modes of Transmission
• Pathogens associated with food can also be
spread through other modes
– Waterborne
– Person-to-person
– Animal-to-person
• Multiple modes of
transmission possible
in a single
outbreak
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Definition of Outbreak
• Two or more cases of a similar illness among
individuals who have had a common exposure
• Critical components of definition
– Same diagnosis or symptoms and signs
suggestive of same illness
– Clear association between cases, with or
without a recognized common source
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Definition of Cluster
• More cases than expected for given
geographic location and time
• No immediately obvious association between
cases
• Suggestive of an outbreak but needs further
exploration to make determination
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Class Question

Is this an outbreak?
Development of nausea and vomiting in three
friends within 30 minutes of eating at a restaurant.
Meets definition of outbreak.
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Class Question

Is this an outbreak?
Diarrhea and abdominal pain due to
Salmonella Agona (an unusual serotype only
seen once before) in 24 persons in one state.
Does not meet definition of an outbreak
because no obvious association between
cases. The number of cases is higher than
expected and deserves further exploration.
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Class Question

Is this an outbreak?
A single case of botulism.
Does not meet definition of an outbreak used
in this course because there is only one case.
However, single cases of certain rare and
serious conditions, such as botulism, toxin
poisoning, or chemical contamination, are
considered public health emergencies and
elicit an outbreak-like response.
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Primary Goals of Outbreak Investigations 
• Stop current outbreak as soon as possible by
implementing effective control measures and
• Prevent similar outbreaks in future.
To achieve these goals, you must rapidly identify
the cause of the outbreak including:
– People at risk (and characteristics)
– Causative agent
– Mode of transmission and vehicle
– Source of contamination
– Contributing factors
– Environmental antecedents
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
To do all these things ….
you need an Outbreak
Investigation Team.
Foodborne diseases and outbreaks > The team
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Outbreak Investigation Team
• Composition varies but almost always needs
knowledge and skills in
– Environmental health
– Epidemiology
– Laboratory
– Public health education
– Communications
– Leadership
• Usually includes environmental health investigator,
epidemiology investigator and/or public health
nurse, and laboratory investigator
Foodborne diseases and outbreaks > The team
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The Team: Env’t Health Investigator
The env’t health investigator focuses
on the contaminated food:
• Receives and interprets foodborne
illness complaints
• Investigates suspected food and/or
food establishment
− Interviews food workers and managers
− Examines food storage, handling, preparation
− Identifies factors that resulted in food
contamination
− Collects environmental and food samples
− Collects paperwork
• Implements control measures
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The Team: Epidemiologic Investigator
The epidemiologic investigator
focuses on cases:
• Analyzes data from pathogenspecific surveillance and
identifies clusters
• Characterizes cases by time, place, and person
• Plans epidemiologic studies
• Interviews cases and healthy controls
• Analyzes and interprets results of epidemiologic
studies
Foodborne diseases and outbreaks > The team
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The Team: Public Health Nurse
The public health nurse focuses
on patients:
• Interviews patients
• Collects clinical specimens from
patients
• Administers questionnaires for
epidemiologic studies
• Advises patients on how to prevent spread of
illness
• Provides public health education
Foodborne diseases and outbreaks > The team
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The Team: Laboratory Investigator
The laboratory investigator
focuses on specimens:
• Analyzes clinical, food, and
environmental specimens
• Interprets test results
• Advises team about tests and collection, handling,
storage, and transport of specimens
• Coordinates additional testing by partner labs
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The Team: Other Skill Sets
Other persons often included on outbreak
investigation team:
• Interpreters
• Public health officer
• Veterinarians
• Public health educator
• Health care providers
• Clerical staff
• Industry members
• Public information
officer
• Regulatory investigators
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The Team: Together
• Work together and support each other
• Team responsibilities
− Develop hypotheses about outbreak source
− Prioritize and assign activities
− Interpret investigation findings
− Determine how far to take an investigation
− Develop public messages
− Decide on control measures
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Group Exercise
Working alone or with others who are from the
same jurisdiction, complete the outbreak
investigation team matrix at the end of the module.
1. Examine the roles and responsibilities listed
under each outbreak investigation team member.
2. Insert your name and the names of your team
members in the appropriate cells.
3. Which responsibilities are not covered? How
might these gaps be filled?
4. Are there others included on
your team? What do they do?
Time limit: 10 minutes
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Quick Quiz
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Quick Quiz
1. Which of the following causative agents is the
most common cause of foodborne disease
outbreaks in the United States?
A. Viruses
B. Bacteria
C. Parasites
D. Chemicals
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Quick Quiz
2. Some foodborne pathogens can also be
spread by water, from person-to-person, and
from animal-to-person.
A. True
B. False
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Quick Quiz
3. An outbreak is an increase in the number of
cases of a particular disease greater than is
expected for a given time and geographic
location.
A. True
B. False
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Quick Quiz
4. Which of the following is a primary goal for
undertaking foodborne disease outbreak
investigations?
A. To study the natural history of the causative
agent
B. To train staff
C. To stop the current outbreak by
implementing effective control measures
D. To respond to public concerns
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Quick Quiz
5. Knowledge and skills from all of the following
disciplines should be represented on every
foodborne outbreak investigation team
EXCEPT
A. Environmental health
B. Epidemiology
C. Laboratory
D. Industry members
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