Outbreak Questionnaires and Interviewing Tips - Oregon.gov
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3/8/2022
Outbreak Questionnaires
and Interviewing Tips
Rosalie Trevejo, DVM, MPVM, PhD
Oregon Health Authority
Acute & Communicable Disease
Prevention Program
1
Objectives
1. Review interviewing tips for outbreak investigation
2. List information needed from outbreak
questionnaires
3. Describe process for developing questionnaires
4. Describe methods for administering questionnaires
5. Discuss potential concerns of respondents
6. Consider challenges of outbreak investigation
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1. Interviewing Tips
30-minute Interviewing Cardinal Rules
https://www.youtube.com/watch?v=HNZm7z_JEL
w&feature=emb_logo
9-minute Quick Review- Do’s and don’ts of
outbreak interviewing
https://www.youtube.com/watch?app=desktop&v=
O6gKLQpEkfY
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2. Purpose of Questionnaires
For outbreak investigations
Gather information for generating and
testing hypotheses about cause of
outbreak
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Characterize the outbreak
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3. Developing the questionnaire
Develop hypothesis:
• Interview a few ill people
• Use open-ended questions
• Look for common themes among responses
Test hypothesis using questionnaire:
• Collect facts that lead to acceptance or rejection
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Testing Your Hypotheses
Use closed-ended questions that need no interpreting
• Require yes or no answer
• Specific, without embroidered details
Examples:
• “Did you eat the potato salad?”
• “Did you ride the MAX train on Thursday last week? On Friday
last week?”
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Writing the questionnaire
Customizable template questionnaires are
available at OHA ACDP website
Foodborne outbreak investigation tools
https://www.oregon.gov/oha/PH/DISEASESCONDITIONS/COMMUNICABLEDISEASE/
OUTBREAKS/GASTROENTERITIS/Pages/Outbreak-Investigation-Tools.aspx
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Who was
interviewed?
What was the
exposure of
concern (where,
when)?
Looking for the
“why”: possible
risk factors
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What symptoms and
clinical information?
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Time factors:
• When did symptoms begin?
• How long did they last?
Helpful to refer to calendar
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How severe was illness?
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4. Methods for administering
questionnaires
Telephone = most common and efficient method
– Quick
– Inexpensive
– Sensitive (does problem truly exist?)
• Disadvantages:
– Need cooperation from those called
– Possible bias: do those who answer phone
differ from those who don’t?
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Administering questionnaires
In-person interview
• More accurate to obtain complex information
– When observations important
– May enhance data quality
• Disadvantages
– More expensive than phone
– Time-consuming
– Staff intensive
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Administering questionnaires
Web based (e.g., Survey Monkey, Inquisite, Google Forms)
Advantages:
• Quickly develop and launch questionnaire
• Can reach many people quickly
• Low cost and staff time
Disadvantages:
• Can’t ask clarifying questions
• Responses may be less complete
• Confidentiality? Using outside servers
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Example - Survey Monkey
2020 Salmonella Newport outbreak: embedded link
Recruit cases and controls (not sick)
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Administering questionnaires
Self-administered
• Most common
Proxy
• Parents often answer for children (
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Concerns among Respondents
Some individuals selected for interview
during outbreak investigation may
challenge or question your legal authority
in contacting them for interview
OAR 333-019-0000
Responsibility of Public Health
Authorities to Investigate Reportable
Diseases
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6. Challenges in outbreak
investigations
• Time constraints
• Reliance on a facility or others
• Reliance on self-administered questionnaires
• LPHA staffing: availability, competing priorities
• Uncertain how much to do, for how long, other priorities
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You don’t have to do this alone!
On-call ACDP epidemiologists or the Urgent
Epidemiology Response Team (UERT) are available
24/7 to consult and assist with outbreaks.
ACDP: 971-673-1111
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Questions?
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11Study Design and Analytic Epidemiology
for Outbreak Investigations
Rosalie Trevejo, DVM, MPVM, PhD
Oregon Public Health Division
Acute and Communicable Disease Prevention
1
Objectives
• Define analytic epidemiology
• Describe types of studies to investigate outbreaks
• Discuss control group selection
• Prepare a 2 x 2 table
• Calculate and interpret measures of association
2
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1Analytic Epidemiology
• Differs from descriptive epi (person, place, time)
• Examines risk factors for developing disease
• Uses a comparison group (controls)
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Developing a Hypothesis
• Use descriptive epi to develop hypothesis
• Evaluate hypothesis:
Look at exposures and outcomes
Collect data systematically
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2Exposure and Outcome
• Exposure= potential risk factor
Ate a food
Worked with a chemical
Had a certain behavior (e.g., smoking)
• Outcome= Disease
Cancer
Diarrhea
Injury
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Common Types of Studies
• Cohort
• Case-Control
• Case-case
• These are observational studies, as compared with
experimental studies
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3Cohort Design
• Start with defined group, classified by exposure
status
Exposed group
Non-exposed group
• Assess who developed disease
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Cohort Studies examples
• Nurse’s Health Study- 1970’s www.nhs3.org
120,000 female nurses – risk factors for cancer and
cardiovascular disease
• Outbreak following a wedding reception
• Illness in a school classroom
• Outbreak after church potluck
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4Why use a cohort?
• Known denominator: # at risk of disease
• Compare exposed and unexposed groups
• Not always possible to define cohort
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Cohort Study
Defined Population
Not
Exposed
Exposed
Don’t Don’t
Develop Develop
Develop Develop
Disease Disease
Disease Disease
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5Cohort Study
Everyone who attended the wedding reception
Ate melon Did not eat
from buffet melon from
buffet
Didn’t Didn’t
Developed Developed
develop develop
Salmonella Salmonella
Salmonella Salmonella
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Case-control Design
• Classify people by outcome
Cases- have disease
Controls- do not have disease
• Assess past exposure
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6Case-control study examples
• Smoking and lung cancer, 1950
• Community-wide Salmonella
outbreak associated with a
commercially distributed
product
• Restaurant outbreak of norovirus
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Selecting Controls
• Do not have the disease, but at risk of disease
• Must have had potential for exposure
• Should be representative of cases
• Key: If they developed the disease, could they be
identified as case?
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7Examples of control groups
• Others who ate at same restaurant
• Neighborhood residents
• Family members
• Friends
• Coworkers
• Random digit dialing
• Classmates
• Medical clinic patients
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Case-control Study
Disease Not ill
(Case) (Control)
Not
Exposed Not Exposed Exposed Exposed
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8Case-control Study Example
Not ill
Salmonella
(control)
case
Ate eggs Did not eat Ate eggs Did not eat
eggs eggs
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Advantages & Disadvantages
Cohort Case-control
Advantages Can evaluate rare exposures Quick
Can calculate risk Smaller size
Less expense
Can evaluate rare disease
Disadvantages Inefficient if incubation is long Recall bias
Potential expense Selection bias
Loss to follow up
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9Measures of Association
• Quantifies magnitude of statistical association
between exposure and disease
• Cohort study: relative risk (RR)
• Case-control study: odds ratio (OR)
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2 X 2 table
Diseased Not Row total
diseased
Exposed a b a+b
Not
c d c+d
exposed
Column a+b+c+d=
a+c b+d
total Grand total
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10Cohort Study: Relative Risk (RR)
• Risk of disease in exposed risk of disease in unexposed
• RR= a/(a+b) c/(c+d)
Disease
Yes No
a b
Exposure
Yes
c d
No
• Reflects magnitude of association between exposure and
disease
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Calculate RR for Cohort Study
• Salmonella Enteritidis outbreak among group of
coworkers that had catered lunch with taco bar
• 40 workers ate fresh salsa; 30 developed
Salmonella Enteritidis and 10 did not
• Another 40 workers did not eat fresh salsa;
2 developed Salmonella Enteritidis and 38 did not
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11Relative Risk 2 X 2 table
No
Salmonella
Salmonella Total
Enteritidis
Enteritidis
Salsa a b a+b
No salsa c d c+d
RR =
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Relative Risk conclusion:
Those who ate salsa had
higher risk (15X) of
developing Salmonella
Enteritidis than those who
didn’t eat salsa
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12Case-Control Study: Odds Ratio (OR)
• Compare odds of exposure for cases and controls
• Odds Ratio (OR) =
a/c b/d
ad/bc
Disease
Yes No
a b
Yes
Exposure
Cross product
No
c d
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Case-Control Study: Calculate OR
• Cases: 40 restaurant patrons with Salmonella
Enteritidis; 30 ate eggs and 10 did not
• Controls: 40 restaurant patrons without Salmonella
Enteritidis; 2 ate eggs and 38 did not
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13Odds Ratio 2 X 2 Table
Salmonella No Salmonella
Enteritidis Enteritidis
Eggs a b
No eggs c d
Total a+c b+d
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Odds ratio 2X2 table results
• Odds Ratio (OR) = (a*d)/(b*c)
•
• OR=
• Conclusion:
Cases were ___ times
more likely than controls to
have eaten eggs
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14Case-case study: hypothesis
generating
• Compare exposures of cases with exposures of a different
group of cases
• Attempt Shotgun interview of Salmonella and STEC cases
• Compare exposure frequencies of suspected outbreak cases
with overall frequencies: example from STEC cluster
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Statistical Association
• p-value (e.g., PStudy Design and Analytic Epidemiology
Questions?
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16TAKING ACTION DURING
DISEASE OUTBREAKS
June Bancroft, MPH
Oregon Health Authority
Acute & Communicable Disease Prevention Program
1
Objectives
Describe the steps in conducting an environmental
health assessment
Describe selected actions and measures to control or
prevent further transmission
Understand who are the stakeholders in taking action
Describe elements of decision-making when evidence of
an outbreak is not conclusive
List factors that influence taking action on public health
recommendations during outbreaks
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1Environmental health assessment
• Identify critical points where contamination could occur
• Identify behavioral risks or procedures
• Devise effective prevention and control interventions
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Environmental Assessment
• Take action to eliminate sources of contamination or
poor food handling practices
• Set up effective ongoing monitoring of food safety
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2Regulatory Outbreak response
Inspection
When Regularly In response to
undertaken scheduled specific problem
Time focus Today Past
Focus of effort Ongoing Food safety
processes problems related to
focusing on implicated food
common during outbreak
problems period
Who initiates Regulatory Outbreak
agency investigation team
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Describe the implicated food
• What are the raw ingredients
• Chemical characteristics, e.g. pH
• Source of the food item
Polling Question
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3Observe procedures
• Cleaning, storage, handling,
transport of food
• Temperature history
• Cooking methods
• Hot-holding or refrigeration
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Polling Question
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4Wooden cutting
board cleaned with
Celery stored under Celery and red
50 lbs. bag Washed and soapy cloth
thawing chicken pepper from
of potatoes chopped
grocery store
from
Farmer B Eggs in trays of 32 from
Eggs boiled Eggs Potatoes,
Farmer B, stored in walk-in
for 10 min. sliced celery, red
refrigerator
pepper, and
5 lbs. potatoes Potatoes boiled in Potatoes Cubed potatoes eggs mixed
washed and water until tender cooled and marinated in gently with
peeled cubed French dressing wood spoon
Knife used to cut other items
Same wooden spoon used
cleaned with soapy water at 4 cups of mayon-
to get mayonnaise and all
end of day naise added and
mixing
stirred into mixture
with wooden spoon
Stored in walk-in
Potato salad placed in Paprika
refrigerator at 4C Chopped parsley
resealable container sprinkled
(39 F) for up to 2 stirred into mixture
(cylindrical 8 in. x 14 in.) on top
days
Potatoes cooled and
Brand Z parsley washed and
Served directly from Paprika from chopped finely
container onto grocery store
customer’s plate with
Fresh parsley from
ice cream scoop
grocery store
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Take measurements
• Time - how long was food held or stored
• Temperature - to which food was exposed
• Storage conditions - types of containers,
location of containers
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Polling Question
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5Talk to food handlers and assess
situation
• Food handlers often know more than supervisors about
what happens routinely
• Level of experience
• Staff turnover
• Knowledgeable supervision
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Collect food specimens if available
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6Salmonella Braenderup investigation
15 F 10/21/09
81 F 11/5/09
4 M 1/16/10
26 M 1/12/10
1 M 1/17/10
Epidemic Curve,
2 M 1/18/10 Salmonella Braenderup,
17 M 1/10/10 2010-023
22 F 1/31/10 7
Confirmed case count
6
16 F 2/13/10 5
10 F 2/13/10 4
3
85 M Unknown 2
1
5 F 3/8/10 0
Month of Onset
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Compare hypothesis with
established facts
• 100% of cases consumed milk
• OR of 5.8 for milk consumption (case-control)
• Median age = 13 (range 1–88)
• Locally distributed product along I-5
• Not asked of all cases, but Brand Q Dairy cited 3 times
• Brand Q served by 7 of 8 schools
• Matching environmental samples for S. Braenderup
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7OPHD, LHD, and ODA visit facility
• Walk-through during operations
• 132 environmental specimens
collected: convenience sample
Raw milk receiving, pasteurization
Filler room, Cold holding room
Crate conveyor & washing system
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1 crate (of 2 swabbed)
Results, 8/14:
3 sites on crate conveyor system
5 positives 1 floor drain
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8Implement control and prevention measures
• Plant closed for cleaning
• ODA, OPHD, LHD collect 230 more samples
• Media coverage emphasizes container
contamination
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Food trace back or recall
Local, State and Federal partners of
various disciplines are involved
“Three-Legged Stool” of investigations
• Epidemiology: Determining who, what, when, where, and how
• Laboratory: Food, environmental, and clinical samples
• Environmental Health
– Trace-back and trace-forward
– Clinical, product, and environmental sampling
– Facility assessments
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9Food Safety and Inspection Service
Is part of the U.S. Department of Agriculture responsible
for ensuring that the nation's commercial supply of meat,
poultry, and egg products is safe, wholesome, and correctly
labeled and packaged.
• FSIS employs approximately
10,000 total personnel; over
7,500 are field personnel.
• FSIS oversees the production of
approximately 100 billion pounds
of meat, poultry, and pasteurized
egg products.
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10When the evidence of the source
of an outbreak is suggestive but
not conclusive, act if:
• the disease is serious and potentially fatal
• the population at risk includes those likely to have poor
outcomes (infants, frail elderly, immunocompromised)
• exposure is suspected to be ongoing or widespread
• control measures can be implemented with limited
economic, legal, or political impact
Polling Question
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Surveillance of outbreaks of waterborne
infectious disease: categorizing levels of
evidence
Tillett, Louvois, Wall Epidemiol Infect 1998; 120:37-42
A= pathogen found in Level of Evidence
water Strong: A+C or A+D or
B=water quality failure, B+C
pathogen not found in
water Probable: B+D or A
C=Analytic association only
of water an illness
Possible: B only or D
D=Descriptive epi
suggests water is only
source and excludes
other explanations
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11Control Measures
• Hand washing by patients and all caregivers
• No food handling while ill
• No working while ill in high-risk settings with vulnerable
persons: daycare or direct care
• Careful hygiene when handling items soiled with excreta
• “Cohort” individuals
• Ensure recommended cleaning methods
• Remove items from menu, modify recipes
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1225
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Communicate results of the
outbreak investigation to:
• Providers
• Media
• Decision-makers
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Educate those who can help
control and prevent disease
• Child care workers
• Food handlers
• Administrators of high-risk facilities
• Staff who write policies and procedures
• Nursing home staff
• Event organizers
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14Discuss recommended actions
• Solicit and listen well to feedback
• Modify recommended actions, if possible, to make them
feasible and acceptable
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Factors that influence carrying out
public health recommendations
Funding
Legislation
Behavioral changes by workers
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15Effective action increases if:
Make timely reports to decision-makers
-Frequent reporting as outbreak unfolds
-Help decision-makers “own” the investigation
Maintain contact with the media
-Press releases as appropriate
-Keep contacts up to date with details
Develop concrete and specific messages
-Boil water
-Clean up mosquito habitat
-Get a flu shot/immunizations
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Hot wash
• Document what lessons you learned in an after-action
report
• Your experience can help others
• Increases local health department credibility
Don’t forget to communicate
what you learned during the
outbreak !!!
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16Reconsider your hypothesis?
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1735
Ground beef outbreak –
E. coli O157:H7
• Purchase history information was obtained for 4 case-patients
• Of the 5 purchases made by 4 case-patients, 80% (4/5) of the
purchases were 85% lean ground beef and 1/5 (20%) was 90% lean
ground beef
• Due to lack of information on grinding log records, as well as a
company-wide policy of once-a-day cleaning of grinding equipment,
trace-back to federal establishments was not possible
• In total, trace-back identified 15 possible ground beef suppliers
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18This Directive provides information on:
• Factors that determine the need for an investigation
• Product sampling considerations during an investigation
• Procedures for trace-back and trace-forward activities
• Considerations for determining the epidemiological
association between illness and product
• Agency actions based upon investigation findings
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Federal Register Proposed Rule,
published on 7/22/14
Records To Be Kept by Official Establishments and Retail Stores That
Grind Raw Beef Products
Amends recordkeeping regulations to specify that all official establishments and
retail stores that grind raw beef products for sale in commerce must keep
records that:
• Disclose identity and contact information of suppliers of all source
materials for each lot of raw ground beef
• Include components and carryover from one lot to next
• Document lot numbers and amount of each component used (pounds)
• Document date and time each lot produced
• Document date and time grinding equipment was cleaned and sanitized
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19Urgent Epidemiologic
Response Team (UERT)
Call ACDP at (971) 673-1111
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E. coli Case Study
On further analysis, only one factor remained statistically
significant: drinking beverages from vendors who were
supplied by water from well #6. As part of the
environmental investigation, samples of water were tested
from well #6, from the distribution pipe to the vendor area,
and from the outlet pipe at the vendor area. Although E.
coli O157 is not often isolated from water supplies, all 3
sites at the fairgrounds yielded E. coli O157:H7.
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20Question 1
What control measures might you recommend for control
of this outbreak?
Question 2
a. Who needs to know what you recommend? Why?
b. How will you communicate your findings?
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41
Oregon Statues and Administrative Rules
5-104.12 Alternative Water Supply.
(B) If approved by the local public health authority, water
for single-event temporary food establishments without a
public water supply may be obtained from a well that has
been tested for coliform bacteria within 60 days prior to the
event. The local public health authority may require
additional testing or an evaluation of the well and premises
as part of the approval process.
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21Epidemiology in Action
It takes a team
1
Shiga toxin-producing E. coli
Washington state cases N=501
• Age range 4 months-88 years,
median 8 years
• 49% female
2
13
Outbreak initiated actions
• E. coli O157:H7 was upgraded to become a national reportable
disease
• The Food and Drug Administration (FDA) increased the
recommended internal temperature for cooked hamburgers from
140 °F (60 °C) to 155 °F (68 °C)
• The United States Department of Agriculture(USDA) – Food Safety
Inspection Service (FSIS) introduced safe food-handling labels for
packaged raw meat and poultry retailed in supermarkets, testing for
E. coli O157:H7 in ground meat
4
2More actions
• USDA classified E. coli O157:H7 as an adulterant in raw meat
• USDA introduced the Pathogen Reduction and Hazard Analysis and
Critical Control Point (PR/HACCP) program
• National Cattleman’s Beef Association (NCBA) created a task force
to fund research into the reduction of E. coli O157:H7 in cattle and
slaughterhouses
• Jack in the Box completely overhauled and restructured their
corporate operations around food safety priorities, setting new
standards across the entire fastfood industry.
5
Multi-state Outbreak of E. coli O157:H7
• 205 cases
• 26 states affected
• Onsets 8/1/06 - 9/15/06
• 141 (71%) female
• 103 (51%) hospitalized
31 (16%) HUS
3 deaths
6
37
7
8
8
49
Persons infected with the outbreak strains
of Salmonella Heidelberg, by State*
Oregon cases N=17
• Age range 2-55 years,
median 21
• 59% female
• 38% of ill persons were
hospitalized, and no deaths
were reported.
• Most ill persons (77%) were
reported from California.
10
5Persons infected with outbreak strain of Salmonella
Heidelberg by week of illness onset*, 2013-2014, U.S.
n=633 for whom information was reported as of July 24, 2014
11
USDA Proposes New Measures to Reduce Salmonella
and Campylobacter in Poultry Products
SUMMARY:
The Food Safety and Inspection Service (FSIS or ‘‘the
Agency’’) is announcing that it will begin assessing
whether establishments meet the pathogen reduction
performance standards for Salmonella and
Campylobacter in raw chicken parts and not-ready-to-eat
(NRTE) comminuted chicken and turkey products.
In 2015 new standards
in ground chicken
and turkey products
12
6Multi-state Outbreak of Salmonella
Typhimurium Infections
•41 ill in 21 states, 16% hospitalized, 0 deaths
•54% cases female,
•AgeMulti-state Outbreak of Salmonella Saintpaul Infections
•84 ill in 18 states, 28% hospitalized, 0 deaths
•62% cases female,
•AgeMulti-state Outbreak of Salmonella
Typhimurium Infections
Age range 0-76 years
69%November 10th 2008
Salmonella Typhimurium isolates with an unusual
DNA fingerprint or pulsed-field gel electrophoresis
(PFGE) pattern reported from 12 states.
• < 1 to 98 years, median age of patients is 16 years
21% are age < 5 years
17% are > 59 years
• 48% of patients are female.
• 24% reported being hospitalized, 9 deaths
19
19
April 20, 2009, 714 persons infected with the outbreak strain
of Salmonella Typhimurium have been reported from 46 states
20
20
1021
Actions – January 2009
• On January 28, 2009, PCA announced a voluntary recall of all
peanuts and peanut products processed in its Blakely, Georgia
facility since January 1, 2007 and reported that production of all
peanut products had stopped. More than 2833 peanut-containing
products produced by a variety of companies may have been made
with the ingredients recalled by PCA.
• Peanut butter and peanut paste, the expanded recall includes
roasted peanuts and other peanut products and was based in part on
laboratory testing information from the company.
22
1123
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24
12Age range 1-91 – median 41
51% male
12 hospitalizations
No deaths
25
25
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26
1327
27
Epidemic curve, Salmonella
Typhimurium
Oregon cases N=13
• Age range 0-27, median 2 years
• 62% female
• 1 hospitalization
• No deaths
28
28
14Persons infected with the outbreak strain
of Salmonella Typhimurium, by State*
29
29
30
30
15Vaccination coverage, Measles outbreak,
France
31
31
Measles cases by rash onset, France,
2008−2011
32
32
16Geographic spread of
measles, France,
October
2008−September 2011
33
33
17You can also read
