1Surveillance and outbreak detection Foodborne Disease Outbreak Investigation Team Training: Module...
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Transcript of 1Surveillance and outbreak detection Foodborne Disease Outbreak Investigation Team Training: Module...
1Surveillance and outbreak detection
Foodborne Disease Outbreak Investigation Team Training:
Module 2 – Foodborne Disease Surveillance and
Outbreak Detection
2Surveillance and outbreak detection
Module Learning ObjectivesAt the end of this module, you will be able to1.Describe the surveillance of foodborne illness
through notification/complaint systems.2.List ways to improve the accuracy of a food
history obtained in a foodborne illness complaint.3.Describe the surveillance of foodborne illness
through pathogen-specific surveillance.4.Recognize a possible outbreak using a
notification/complaint system or pathogen-specific surveillance.
5.Describe the role of local public health in national pathogen-specific surveillance.
3Surveillance and outbreak detection
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)
4Surveillance and outbreak detection
Foodborne Illness Notification/Complaint
Systems
5Surveillance and outbreak detection
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
> Notifications/complaints
6Surveillance and outbreak detection
Steps in Receiving Complaints Illness in individual
or group
Interview of complainant
Documentation of information
Key information entered into log
Complaint to local health department
Evaluation of reports over time
for outbreaks
Routine review of log
Evaluation of individual reports
for immediate action
> Notifications/complaints
Starts with complaint by
consumer
Common exposures link
cases over time
7Surveillance and outbreak detection
Interview of Complainant
• Who is affected?
• What is the problem?
• When did problem occur?
• Where?
• Why/how?
(e.g., name, age, and sex) (e.g., symptoms, diagnosis)
(e.g., date/time of onset)
(e.g., travel, water, contact with ill persons or animals, suspect food or meal, food history)
(e.g., place of residence and exposure)
> Notifications/complaints
Example in appendix
8Surveillance and outbreak detection
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 >1 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
> Notifications/complaints
9Surveillance and outbreak detection
Small Group ExerciseDivide into groups of two. One person will be the interviewer; one will be the complainant.
1.The interviewer should solicit a 5-day food history from the complainant.
2.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.
3.Was it easy or difficult? Did you get a complete food history? What approaches were helpful?
Time: 10 minutes
Be prepared to share your experience with the class.
10Surveillance and outbreak detection
Improving Food Histories
• 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
Have complainant
> Notifications/complaints
11Surveillance and outbreak detection
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
> Notifications/complaints
12Surveillance and outbreak detection
Evaluation of ComplaintsIndividual 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
> Notifications/complaints
13Surveillance and outbreak detection
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
> Notifications/complaints
14Surveillance and outbreak detection
Class Question
Person developed diarrhea after eating at a restaurant. Neighbors who ate at the restaurant also are sick but complainant does not know their symptoms.
Likely
Unknown
Unlikely
Which of the following group illnesses are likely to be due to the identified restaurant exposure?
Four friends develop nausea and vomiting, facial flushing, headache, and itching skin within an hour of eating fish at a restaurant.
Family members develop bloody diarrhea within hours of eating at a restaurant.
> Notifications/complaints
Due to Exposure
15Surveillance and outbreak detection
Evaluation of Complaints (cont’d)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
> Notifications/complaints
16Surveillance and outbreak detection
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.
> Notifications/complaints
17Surveillance and outbreak detection
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
> Notifications/complaints
18Surveillance and outbreak detection
Group Exercise
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?
Divide into groups by table. Study the foodborne illness log at the end of this module spanning a 2-week period and determine:
Time: 10 minutes
Be prepared to share your thoughts with the class.
19Surveillance and outbreak detection
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
> Notifications/complaints
20Surveillance and outbreak detection
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
> Notifications/complaints
21Surveillance and outbreak detection
Pathogen-specific Surveillance
22Surveillance and outbreak detection
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
> Pathogen-specific
23Surveillance and outbreak detection
Steps in Pathogen-specific SurveillanceIllness in individual
Analysis of cases for clusters/outbreaks
Individual seeks health care
Specimen collected
Diagnosis by health-care provider/laboratory
Initial report to health department
Submission of isolate to
public health laboratory
Follow-up interview of
case
Further characterization
Entry into electronic database
Forward to CDC
> Pathogen-specific
Starts with positive lab
resultCommon
pathogen links cases over time
24Surveillance and outbreak detection
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
> Pathogen-specific
Example in appendix
25Surveillance and outbreak detection
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
> Pathogen-specific
26Surveillance and outbreak detection
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
> Pathogen-specific
27Surveillance and outbreak detection
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
> Pathogen-specific
28Surveillance and outbreak detection
Analysis by Causative Agent
Month of Diagnosis
Nu
mb
er
of C
ase
Lab-confirmed salmonellosis cases by month of diagnosis, 2010.
All Salmonella
> Pathogen-specific
29Surveillance and outbreak detection
Month of Diagnosis
Nu
mb
er
of C
ase
Lab-confirmed salmonellosis cases by month of diagnosis
Salmonella Javiana
All Salmonella
Analysis by Causative Agent Subtype
> Pathogen-specific
30Surveillance and outbreak detection
Month of Diagnosis
Nu
mb
er
of C
ase
s
Lab-confirmed salmonellosis cases by month of diagnosis
Salmonella Javiana
All Salmonella
Analysis by Causative Agent and Age Group
Salmonella Javiana among persons <5 yrs.
> Pathogen-specific
31Surveillance and outbreak detection
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)
> Pathogen-specific
32Surveillance and outbreak detection
Pathogen-specific Surveillance Issues
• Incomplete detection and reporting
Population
Person Becomes Ill
Person Seeks Care
Specimen Obtained
Lab Tests for Organism
Culture-confirmed Case
Reported
> Pathogen-specific
33Surveillance and outbreak detection
Pathogen-specific Surveillance Issues
• Elapsed time
• Incomplete detection and reporting Patient
eats food
Patient becomes ill
Stool sample
collected
Salmonella identified
Isolates received by
public health lab Case
confirmed as part of
cluster
Incubation period=1-3 d
Time to contact with health care=1-5 d
Shipping time=0-7 d
Serotyping and PFGE=2-10 d
Time to diagnosis=1-3 d
Elapsed Time for Salmonella Reporting
> Pathogen-specific
34Surveillance and outbreak detection
Pathogen-specific Surveillance Issues
• Availability of isolate for further characterization
> Pathogen-specific
• Elapsed time
• Incomplete detection and reporting
35Surveillance and outbreak detection
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 resultMeans to link cases Common exposures Same pathogenLinkage 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
36Surveillance and outbreak detection
National Pathogen-Specific Surveillance Systems
37Surveillance and outbreak detection
• 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
National Pathogen-specific Surveillance
> National surveillance
38Surveillance and outbreak detection
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 System—enteric bacteria)
− Submission of Salmonella, Shigella, E. coli O157, Campylobacter, and non-cholerae Vibrio to CDC
− Determines trends in antimicrobial resistance
> National surveillance
39Surveillance and outbreak detection
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.
> National surveillance
40Surveillance and outbreak detection
What difference does one local case make?
6
1
11
1
• Two E. coli O157:H7 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
> National surveillance
41Surveillance and outbreak detection
Quick Quiz
42Surveillance and outbreak detection
Quick Quiz
1. 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
A. True
B. False
43Surveillance and outbreak detection
Quick Quiz2. 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?
A. Ill persons all have the same symptoms.
B. Ill persons shared food or a meal prior to onset of illness and had no other common exposures.
C. Onset of the illness is consistent with the timing of the exposure.
D. All of the above
44Surveillance and outbreak detection
Quick Quiz
3. Which of the following can improve the accuracy of a food history solicited during a foodborne illness complaint?
A. Have case look at a calendar and identify key events to jog memory.
B. Have case review credit card or cash register receipts to identify where or what they ate.
C. Enlist help of dining partners.
D. All of the above
45Surveillance and outbreak detection
Quick Quiz
4. All of the following are true of pathogen-specific surveillance EXCEPT
A. Detects all types of foodborne illness.
B. Relies on reports from health-care providers and clinical laboratory staff.
C. Is the primary means to detect widespread outbreaks such as multistate outbreaks.
D. Has an inherent lag in reporting due to time necessary to confirm pathogen through laboratory testing.
46Surveillance and outbreak detection
Quick Quiz
5. All of the following are important roles for local health departments in national pathogen-specific surveillance EXCEPT
A. Collect information on local cases in a format consistent with other investigators.
B. Share case reports with state health department in a timely fashion.
C. Be alert to outbreaks in other jurisdictions.
D. Submit all patient isolates directly to CDC.