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>> Working on an outbreak
investigation?

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It's important to shift from the
mindset of a routine inspector

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to an outbreak investigator,
so you can understand how

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and why the outbreak occurred.

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This video reviews
the importance

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of identifying practices
and factors

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that contribute to the outbreak.

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Finding these contributing
factors helps you recommend the

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right control measures.

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Let's review how
outbreaks occur.

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When a foodborne illness
outbreak is suspected,

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the responsible jurisdiction
must determine

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where in the farm-to-fork
continuum the problem occurred.

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This continuum includes
harvesting, manufacturing,

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distribution, and
points of final service,

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such as a restaurant
or someone's home.

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The responsible jurisdiction
will also investigate the

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factors that led
to the outbreak.

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These are known as
contributing factors.

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The underlying root causes
of these factors are known

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as environmental antecedents.

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This video will focus

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on identifying contributing
factors.

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Investigators from 3 scientific
disciplines are essential

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to the investigation:
epidemiology, laboratory science,

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and environmental health.

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These 3 disciplines
collect critical information

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on the components of
the disease triangle.

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This information helps the
investigators understand the

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outbreak, identify practices
that contributed to the outbreak,

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and recommend actions
to control it.

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Let's take a closer
look at each discipline.

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Epidemiologists collect
data about the host

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of the foodborne illness.

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They answer the questions
"Who got sick?"

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and "When did they get sick?"

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Epidemiological data is
used to form a hypothesis

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on the suspected
pathogen or other agent.

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The data also help identify
implicated food items

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that helps guide
the investigation.

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Laboratory scientists
collect data about the agent

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that is causing the
foodborne illness.

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They answer the question
"What agent got people sick?"

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Environmental health specialists
collect data on the environment

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that allowed the agent
to infect the host.

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This information helps
answer the questions

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"How did the foodborne
agent infect the host--

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what factors led
to that happening?"

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And "Why did those
factors occur?"

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Environmental health
specialists use epidemiologic

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and laboratory data to guide
the environmental assessment.

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Identifying the factors
that lead to outbreaks

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and their underlying causes
requires a different approach

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and mindset than performing
a routine inspection.

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An environmental assessment is a
systematic process that focuses

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on specific foods,
processes, and people.

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Food safety violations might
be identified during the

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environmental assessment

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that are not associated
with the outbreak.

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Environmental health specialists
must distinguish these general

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violations from actual
conditions

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that led to the outbreak.

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While violations not associated
with the outbreak are important,

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the immediate goal of an
environmental assessment

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is to identify the specific
contributing factors

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and their underlying
root causes.

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Let's take a closer look at
these contributing factors.

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What exactly are they?

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Contributing factors are
the factors and practices

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that led to the outbreak.

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They fall into 3 categories:

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contamination, proliferation, and
survival factors.

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These 3 categories refer to the
type of food safety failures

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that most likely occurred
before the outbreak.

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Keep in mind you
might identify more

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than 1 contributing factor
during the investigation.

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The first type of contributing
factor, contamination,

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is when pathogens or other
agents get into food.

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They can come from many
sources, including people,

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pests, and the environment.

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Contamination can occur

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at any point along the
farm-to-fork continuum.

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One example is when
a raw animal product

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such as raw chicken
cross-contaminates ready-to-eat

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food such as salad.

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Another example of a
contamination factor is

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when a sick food
worker handles food

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with their bare,
contaminated hands.

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Let's look at the second major
category of contributing factors:

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proliferation.

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Proliferation is when pathogens
are growing in the food.

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Food that is held, cooled,
reheated, or prepared

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at the wrong temperatures

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for a long time can allow
harmful bacteria to grow.

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For example, a stock pot of
chili is improperly cooled

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and held in the temperature
danger zone

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for hours, allowing <i>Clostridium
perfringens</i> to proliferate.

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Another example

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of a proliferation
contributing factor is

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when sliced deli meat is
held in a refrigerator

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for months, allowing <i>Listeria
monocytogenes</i> to proliferate.

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Our third contributing
factor category is survival.

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Survival is when pathogens
survive a process meant

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to kill or reduce them.

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Survival contributing
factors apply to foods

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that require cooking--such as
raw beef, pork, and poultry--

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to ensure possible
pathogens are eliminated

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or reduced to safe levels.

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One example of a
survival factor is

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when a hamburger is not cooked

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to a hot enough temperature,
allowing <i>E. coli</i>

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to survive the cooking process.

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Another example is sashimi

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or raw wild salmon not
being frozen long enough

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or at the right temperature to
ensure parasites are destroyed.

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To identify these
contributing factors,

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the environmental health
specialist's role changes

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from that of a regulator
and inspector to one

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of a detective seeking
to solve a mystery.

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Like a detective,

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the environmental health
specialist gathers clues

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and uses them to determine how
and why the outbreak happened.

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Remember: outbreak
investigations differ

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from routine inspections.

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The environmental
assessment piece

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of the outbreak investigation
looks at the big picture

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to identify what
led to a breakdown

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in food safety, while
routine inspection focus more

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on violations.

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And while the environmental
assessment focuses

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on food safety issues that
may have occurred in the past,

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an inspection is a snapshot

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of current food safety
practices and conditions.

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Identifying contributing
factors should be based

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on information gathered during
the environmental assessment,

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not the results of routine
inspections.

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Most of these assessments
require multiple site visits

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as more information
is made available

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about the suspected agent
and implicated food items.

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Let's look at some
common activities

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in the environmental
assessment piece

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of the outbreak investigation.

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Investigators visit the location
to see how food is prepared

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and review food flows
for implicated food.

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Observations should concentrate
on the specific processes

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or practices that
could have contributed

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to the contamination,
survival, or proliferation

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of the suspected agent.

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As part of the environmental
assessment,

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investigators also interview
managers and food workers.

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Since it's not possible to
observe what actually happened

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in the past, the goal
of interviewing is

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to piece together the events
that occurred at the time

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of the exposure and develop
insights into the factors

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that led to a foodborne
illness outbreak

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and also the root causes.

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Investigators often
review or collect records

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to understand what
happened in the past.

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Records can include
invoices, employee sick logs,

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employee schedules, recipes,

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and customer information
for case finding.

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Investigators take
samples of the environment

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or implicated food to be tested
for pathogens or other agents,

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as they still could be
present and available to test.

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For every identified
contributing factor,

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the environmental
specialist must try

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to understand why the
contributing factor occurred.

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These root causes are directly
related to the conditions

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in the food establishment:
the people, equipment, food,

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processes, and economics.

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Once the contributing factors
are identified, it's important

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to use this information
to recommend

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and implement effective,
sustainable control measures.

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Control measures are actions
or activities that are taken

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to prevent, eliminate,
or reduce the occurrence

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of an identified hazard.

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Control measures
can be short-term

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and immediately implemented,

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such as discarding
potentially contaminated food.

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Other control measures
may be long-term,

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such as requiring training

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or changing a preparation
procedure.

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Both short- and long-term
control measures are critical

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for stopping an outbreak
and preventing it

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from happening again
at a specific location.

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Implementing appropriate control
measures requires accurately

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identifying both
contributing factors

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and their underlying
root causes.

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We hope you have
gained an understanding

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of some basic information
about contributing factors:

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what they are, how
they are identified,

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and how they can be used

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to develop effective
control measures.

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For more food safety resources

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for environmental
health practitioners,

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go to cdc.gov/nceh/ehs/food.

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