Foodborne Disease Outbreak Investigation Team Training:

1
Foodborne Disease Outbreak Investigation Team
Training

• Module 2 Foodborne Disease Surveillance and
  Outbreak Detection

2
Module Learning Objectives

• At the end of this module, you will be able to
• Describe the surveillance of foodborne illness
  through notification/complaint systems.
• List ways to improve the accuracy of a food
  history obtained in a foodborne illness
  complaint.
• Describe the surveillance of foodborne illness
  through pathogen-specific surveillance.
• Recognize a possible outbreak using a
  notification/complaint system or
  pathogen-specific surveillance.
• Describe the role of local public health in
  national pathogen-specific surveillance.

3
Foodborne Disease Surveillance

• Many ways to find out about cases of foodborne
  illnesses and outbreaks
• Two primary means
• Foodborne illness notification/complaint systems
• Pathogen-specific surveillance (notifiable
  disease reporting)

4
Foodborne Illness Notification/Complaint Systems
5
Notification/Complaint Systems

• Complaints of illness among individuals and
  groups reported by affected members of the
  community (and others)
• Includes any illness thought to be related to
  food
• Common exposures are used to link cases together

gt Notifications/complaints
6
Steps in Receiving Complaints
?
Illness in individual or group
Complaint to local health department
Documentation of information
gt Notifications/complaints
7
Interview of Complainant
?
(e.g., name, age, and
sex)

• Who is affected?
• What is the problem?
• When did problem occur?
• Where?
• Why/how?

(e.g.,
symptoms, diagnosis)
(e.g., date/time of onset)
(e.g., place of residence and
exposure)
(e.g., travel, water, contact
with ill persons or animals, suspect food or
meal, food history)
Example in appendix
gt Notifications/complaints
8
Collecting Food Histories

• Complete food history important including
• Foods eaten in 5 days before onset of illness
• If illness suggestive of norovirus, focus on
  24-48 hours before illness.
• If gt1 ill person, focus on shared foods/meals.
• ALL foods eaten during time period of interest
  (unless focusing on shared foods/meals)
• Details of named events, food establishments, or
  suspect food products
• Information on non-food exposures

gt Notifications/complaints
9
Small Group Exercise

• Divide into groups of two. One person will be the
  interviewer one will be the complainant.
• The interviewer should solicit a 5-day food
  history from the complainant.
• The complainant should respond to questions as if
  they just developed symptoms that day and based
  on what they really ate in the last 5 days.
• Was it easy or difficult? Did you get a complete
  food history? What approaches were helpful?

Be prepared to share your experience with the
class.
Time 10 minutes
10
Improving Food Histories
Have complainant

• Look at a calendar
• Describe each meal in time period
• Identify key events to jog memory
• Review receipts or menus
• Enlist help of dining partners
• Consider specific list of foods
• Think about food preferences
• Rule out or rule in specific foods

gt Notifications/complaints
11
Entering Information into Log

• Extract key information from the complaint to
  facilitate examination of reports over time
• Date of illness onset
• Predominant signs and symptoms
• Name of food thought to have caused illness
• Names of eating places or gatherings
• Source of water and type
• Other exposures
• Transfer information carefully
• Use consistent abbreviations and codes

gt Notifications/complaints
12
Evaluation of Complaints

• Individual reports of concern
• Symptoms suggestive of serious illnesses
• Laboratory-confirmed diagnoses
• Reports of obvious food safety problems
• Group illnesses thought to be due to an
  identified, shared exposure

gt Notifications/complaints
13
Group Illnesses Due to Identified, Shared Exposure

• Illnesses are likely to be related to an
  identified, shared exposure (e.g. particular
  meal, event, or establishment), if group members
  have
• Similar signs and symptoms
• Shared a food or meal prior to onset of illness
  and had no other common exposures
• Onset and nature of illness is consistent with
  identified shared exposure

gt Notifications/complaints
14
Class Question
?
Which of the following group illnesses are likely
to be due to the identified restaurant exposure?
Due to Exposure

• Person developed diarrhea after eating at a
  restaurant. Neighbors who ate at the restaurant
  also are sick but complainant does not know their
  symptoms.

Unknown

• Four friends develop nausea and vomiting, facial
  flushing, headache, and itching skin within an
  hour of eating fish at a restaurant.

Likely
Family members develop bloody diarrhea within
hours of eating at a restaurant.
Unlikely
gt Notifications/complaints
15
Evaluation of Complaints (contd)

• Looking at reports over time
• Multiple individual complaints with same exposure
  (e.g., same food establishment or food)
• Multiple individual complaints with clustering by
  time, place, or person
• Overall increase in complaints

gt Notifications/complaints
16
Response to Notifications/Complaints

• Notify epidemiology unit/communicable disease
  staff of laboratory-confirmed diagnoses.
• Refer food safety problem to agency with
  regulatory authority.
• Alert appropriate persons if possible outbreak
  detected.
• Prioritize follow-up of
  commercial establishments.

gt Notifications/complaints
17
Follow-up of Commercial Establishments

• Rational approach to follow-up
• As required by local law/statute or
• If complainant observed specific food safety
  problem or
• If two or more persons (not from same household)
• Have similar illness
• Shared history of eating at
  establishment
• Onset and nature of illness
  consistent with shared foods

gt Notifications/complaints
18
Group Exercise
Divide into groups by table. Study the foodborne
illness log at the end of this module spanning a
2-week period and determine

1. Is the number of complaints what you would expect
   for the period covered?
2. Are there individual complaints of concern?
3. Are there common exposures (e.g. foods,
   establishments) across complaints signaling an
   outbreak?

Be prepared to share your thoughts with the class.
Time 10 minutes
19
Strengths of Notification/Complaint Systems

• Primary means to detect outbreaks that are
• Localized (involving only one jurisdiction)
• Due to diseases with a short incubation period

gt Notifications/complaints
20
Notification/Complaint System Issues

• Inaccurate and incomplete food histories
• Large numbers of complaints
• Anonymous complaints
• Complaints with unknown causative agent
• Inability to exclude unrelated cases
• Inability to link cases based on illness unless
  symptoms very unique or cases report similar
  exposure

gt Notifications/complaints
21
Pathogen-specific Surveillance
22
Pathogen-specific Surveillance

• Also called reportable diseases, notifiable
  diseases, or laboratory-based reporting
• Reports of individual laboratory-confirmed cases
  of foodborne disease by medical and laboratory
  staff with submission of clinical isolates, where
  requested
• Only covers diseases selected by
  public health agency
• Cases linked to each other by
  common pathogen

gt Pathogen-specific
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Steps in Pathogen-specific Surveillance
?
Illness in individual
gt Pathogen-specific
24
Initial Report

• From health-care provider or laboratory
• Standardized form (often pathogen-specific)
• Information of interest
• Patient identifiers
• Basic demographic information
• Clinical information
• Laboratory results

Example in appendix
gt Pathogen-specific
25
Follow-up Interview of Case

• To identify potential exposures leading to
  illness
• Similar to interview for notification/complaint
  system but tailored to specific pathogen
• High-risk food exposures for agent
• Other exposures related to agent (e.g., contact
  with ill people, animals, water)
• Often occurs weeks after
  exposure leading to illness
  resulting in poor recall

gt Pathogen-specific
26
Laboratory Characterization of Pathogen

• Submission of patient isolate to public health
  laboratory for confirmation and subtyping
• Increased detail about the pathogen (e.g.,
  serotyping, PFGE) improves
• Recognition of clusters
• Linking an outbreak with an exposure
• Most critical with common
  pathogens

gt Pathogen-specific
27
Analysis for Clusters

• Examine cases by pathogen over time using
• Different levels of specificity of pathogen
  (e.g., species, selected subtypes)
• Subgroups of population (certain time, place, or
  person characteristics)
• Look for increase in number of cases over
  expected or baseline, indicating
  a cluster

gt Pathogen-specific
28
Analysis by Causative Agent
Lab-confirmed salmonellosis cases by month of
diagnosis, 2010.
All Salmonella
Number of Case
Month of Diagnosis
gt Pathogen-specific
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Analysis by Causative Agent Subtype
Lab-confirmed salmonellosis cases by month of
diagnosis
All Salmonella
Number of Case
Salmonella Javiana
Month of Diagnosis
gt Pathogen-specific
30
Analysis by Causative Agent and Age Group
Lab-confirmed salmonellosis cases by month of
diagnosis
All Salmonella
Number of Cases
Salmonella Javiana among persons lt5 yrs.
Salmonella Javiana
Month of Diagnosis
gt Pathogen-specific
31
Strengths of Pathogen-specific Surveillance

• Primary means to detect outbreaks that are
• Wide-spread (i.e., multijurisdictional),
• Due to prolonged low-level food contamination, or
  
• Due to diseases with a long incubation (e.g.,
  hepatitis A)

gt Pathogen-specific
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Pathogen-specific Surveillance Issues
?

• Incomplete detection and reporting

gt Pathogen-specific
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Pathogen-specific Surveillance Issues
?

• Incomplete detection and reporting

• Elapsed time

gt Pathogen-specific
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Pathogen-specific Surveillance Issues

• Incomplete detection and reporting

• Elapsed time

• Availability of isolate for further
  characterization

gt Pathogen-specific
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Comparison of Surveillance Systems
Notification/ complaint system Pathogen-specific surveillance
Types of foodborne illnesses detected All Only selected diseases
Initiating event Consumer complaint Positive lab result
Means to link cases Common exposures Same pathogen
Linkage of cases across jurisdictions Not usually Yes
Exclusion of unrelated cases Difficult Good
Speed Fast Relatively slow
Types of outbreaks best detected Localized outbreaks short incubation illnesses Widespread low-level contamination events long incubation illnesses
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National Pathogen-Specific Surveillance Systems
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National Pathogen-specific Surveillance

• NNDSS (National Notifiable Disease Surveillance
  System)
• Data from pathogen-specific surveillance
  forwarded to CDC (minimal case information)
• Statistical algorithm used to identify increases
• PulseNet (National Molecular Subtyping Network
  for Foodborne Disease Surveillance)
• Laboratory network that uses standardized pulsed
  field gel electrophoresis (PFGE) methods
• PFGE patterns uploaded by labs for STEC,
  Salmonella, Shigella, Listeria, Campylobacter
• Comparisons of patterns to identify clusters

gt National surveillance
38
National Pathogen-specific Surveillance

• CaliciNet (National Electronic Norovirus Outbreak
  Network)
• Laboratory network that subtypes/sequences
  norovirus isolates related to outbreaks
• Data uploaded to CDC allows linkage of outbreaks
  and identification of new variants
• NARMS (National Antimicrobial Resistance
  Monitoring Systementeric bacteria)
• Submission of Salmonella, Shigella, E. coli O157,
  Campylobacter, and non-cholerae Vibrio to CDC
• Determines trends in antimicrobial resistance

gt National surveillance
39
Role of Local Health Departments

• Local pathogen-specific case reports and
  laboratory results feed into national
  surveillance
• Important for local health departments to
• Collect data in format consistent with other
  investigators.
• Streamline reporting and isolate submission.
• Share case reports with state and submit patient
  isolates to public health laboratory as quickly
  as possible.
• Use national systems to learn about outbreaks in
  other jurisdictions.

gt National surveillance
40
What difference does one local case make?

• Two E. coli O157H7 infections in MN with same
  PFGE pattern both ate tenderized steaks
• Through PulseNet, single cases identified in KS
  and MI both ate tenderized steaks
• Steaks eaten by cases
  from same plant
• Recall of 739,000 lbs.
  of beef
• Outbreak generated
  high levels of concern
  
  about needle/blade
  tenderized steaks

gt National surveillance
41
Quick Quiz
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Quick Quiz

• Typically common exposures are used to detect
  outbreaks through a foodborne illness
  notification/complaint systems whereas a common
  pathogen is used to detect outbreaks through
  pathogen-specific surveillance systems
• True
• False

43
Quick Quiz

• Illnesses in a group are likely to be related to
  an identified, shared exposure (e.g. particular
  meal, event, or establishment), if group members
  have which of the following?
• Ill persons all have the same symptoms.
• Ill persons shared food or a meal prior to onset
  of illness and had no other common exposures.
• Onset of the illness is consistent with the
  timing of the exposure.
• All of the above

44
Quick Quiz

• Which of the following can improve the accuracy
  of a food history solicited during a foodborne
  illness complaint?
• Have case look at a calendar and identify key
  events to jog memory.
• Have case review credit card or cash register
  receipts to identify where or what they ate.
• Enlist help of dining partners.
• All of the above

45
Quick Quiz

• All of the following are true of
  pathogen-specific surveillance EXCEPT
• Detects all types of foodborne illness.
• Relies on reports from health-care providers and
  clinical laboratory staff.
• Is the primary means to detect widespread
  outbreaks such as multistate outbreaks.
• Has an inherent lag in reporting due to time
  necessary to confirm pathogen through laboratory
  testing.

46
Quick Quiz

• All of the following are important roles for
  local health departments in national
  pathogen-specific surveillance EXCEPT
• Collect information on local cases in a format
  consistent with other investigators.
• Share case reports with state health department
  in a timely fashion.
• Be alert to outbreaks in other jurisdictions.
• Submit all patient isolates directly to CDC.