This document discusses the role of laboratories in disease surveillance. Laboratories contribute to surveillance by detecting early warning signals of outbreaks, aiding in outbreak detection, confirming diagnoses and identifying pathogens during outbreaks, monitoring trends in endemic diseases, and evaluating progress towards disease elimination and eradication. Effective surveillance requires coordination between epidemiologists and laboratories, including clear communication and information sharing. Laboratories at different levels have specific roles in surveillance, from routine testing and reporting at peripheral levels to confirmation and capacity building at referral laboratories.

1. E P I D E M I C A L E R T A N D R E S P O N S E
Laboratory Training for Field Epidemiologists
Role of the laboratory in
disease surveillance
Role of laboratory in surveillance
May 2007

2. E P I D E M I C A L E R T A N D R E S P O N S E
Laboratory Training for Field Epidemiologists
Learning objectives
At the end of the presentation, participants should:
• Understand how the laboratory contributes to
epidemiological surveillance
• Understand the principles of laboratory-based surveillance

3. E P I D E M I C A L E R T A N D R E S P O N S E
Laboratory Training for Field Epidemiologists
Laboratories and disease surveillance
Before the outbreak
• Early warning signals
• Outbreak detection
During the outbreak
• Outbreak response and management
In between outbreaks
• Trend monitoring
• Intervention evaluation
• Monitoring progress towards a control objective

4. E P I D E M I C A L E R T A N D R E S P O N S E
Laboratory Training for Field Epidemiologists
Early warning signals
Detection of pathogens that have potential to spread
Sentinel events requiring early control measures
• Isolation of a single epidemic prone isolate
(e.g. non-typhoidal salmonella isolated from a neonate in
a hospital neonatal intensive care unit)
• Emergence of resistant strains in the hospital or the
community (e.g. multi-drug resistant tuberculosis)

5. E P I D E M I C A L E R T A N D R E S P O N S E
Laboratory Training for Field Epidemiologists
Outbreak detection
Outbreak detection by the laboratory
Outbreak detection with assistance from the laboratory

6. E P I D E M I C A L E R T A N D R E S P O N S E
Laboratory Training for Field Epidemiologists
Outbreak detection by the lab
Identification of a cluster of:
• Infections with an unusual pathogen
• Specific subtype of a pathogen
– Outbreak of antibiotic-resistant strains
– Subtypes of a pathogen (e.g. Shigella dysenteriae type I)
Reference centres may capture outbreaks disseminated
over a large area

7. E P I D E M I C A L E R T A N D R E S P O N S E
Laboratory Training for Field Epidemiologists
Outbreak detection with lab help
Epidemiologist captures an increased incidence
Laboratory:
• Confirms the diagnosis
• Allows for a more specific case definition
• Detects a new pathogen
• Provides additional details on the pathogen (e.g., phage type)
Effective participation of the laboratory in surveillance
requires good communication between the
epidemiologists and the laboratories

8. E P I D E M I C A L E R T A N D R E S P O N S E
Laboratory Training for Field Epidemiologists
Laboratory role during outbreaks
Laboratory confirmation of early cases
• On a subset of cases
Identification of new pathogens
Typing of the pathogen
• Link clusters when the epidemiological data is not sufficient
Antimicrobial susceptibility testing to guide treatment
Post-outbreak surveillance
Environmental investigations
Detection of carriers

9. E P I D E M I C A L E R T A N D R E S P O N S E
Laboratory Training for Field Epidemiologists
Laboratory role during outbreaks
For new and emerging pathogens:
•Identify the pathogen
•Develop laboratory tests
•Patient treatment/management
SARS
Courtesy:
The University of Hong Kong

10. E P I D E M I C A L E R T A N D R E S P O N S E
Laboratory Training for Field Epidemiologists
Monitoring endemic disease trends
Confirm diagnosis
• Case definitions that include laboratory criteria
Monitor resistance patterns
Monitor subtypes of a pathogen

11. E P I D E M I C A L E R T A N D R E S P O N S E
Laboratory Training for Field Epidemiologists
Monitoring endemic disease trends
Examples:
Circulating strains of bacterial meningitis
• Impact on treatment protocols
• Impact on immunization policies
Antibiotic resistance
• Methicilin resistant staphylococcus aureus
• Vancomycin resistant enterococcus
• Tuberculosis

12. E P I D E M I C A L E R T A N D R E S P O N S E
Laboratory Training for Field Epidemiologists
0
100
200
300
400
500
600
85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 2000
Year
Number
of
cases
C
B
A
Unknown
Source : InVS and NRC for N. meningitis, Pasteur Institute, Paris
Invasive meningococcal infection
serogroups by year, France, 1985-2000

13. E P I D E M I C A L E R T A N D R E S P O N S E
Laboratory Training for Field Epidemiologists
0
100
200
300
400
500
600
1992 1993 1994 1995 1996
Others
Faciparum
Cases of malaria by species, Region A
1992-1996
The increased proportion of falciparum is an early warning

14. E P I D E M I C A L E R T A N D R E S P O N S E
Laboratory Training for Field Epidemiologists
Eradication/elimination monitoring
The elimination phase requires more specific tests as
positive predictive value decreases
Laboratory confirmed diagnosis
• Polio surveillance
• Measles
Typing helps identifying the origin

15. E P I D E M I C A L E R T A N D R E S P O N S E
Laboratory Training for Field Epidemiologists
0
50
100
150
200
250
80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96
Years
Number
of
cases
National
immunization day
National
immunization day
Cases of polio where wild poliovirus
was isolated in children, District X
1980-1996

16. E P I D E M I C A L E R T A N D R E S P O N S E
Laboratory Training for Field Epidemiologists
Predicting future AIDS trends for
health service planning
Cases of AIDS in City X, 1990-2004
0
100
200
300
400
500
600
700
90 91 92 93 94 95 96 97 98 99 00 01 02 03 04
Years
Number
of
cases

17. E P I D E M I C A L E R T A N D R E S P O N S E
Laboratory Training for Field Epidemiologists
Tuberculosis: new cases, treatment completion and cures,
District X, 1994-1997
0
500
1000
1500
2000
1994 1995 1996 1997
Years
Number
of
patients
Cases
Completion
Cure
Monitoring TB control program to ensure
complete treatment and cure

18. E P I D E M I C A L E R T A N D R E S P O N S E
Laboratory Training for Field Epidemiologists
Establishing laboratory support for
public health surveillance
Identify diseases of public health importance
List diseases that require laboratory confirmation
Determine tests to be performed
Map laboratory facilities and human resources,
including reference laboratories
Establish laboratory networking
Identify a focal person to coordinate laboratory activities
Determine information flow

19. E P I D E M I C A L E R T A N D R E S P O N S E
Laboratory Training for Field Epidemiologists
Define roles and responsibilities, identify referral system
Ensure supplies, logistics, guidelines and forms
Organize communication between lab and epi
• Prompt, regular reporting of results and feedback
Plan quality assurance, biosafety and waste management
Supervise and monitor
Develop epidemic preparedness and response plans
Establishing laboratory support for
public health surveillance

20. E P I D E M I C A L E R T A N D R E S P O N S E
Laboratory Training for Field Epidemiologists
Peripheral level objectives
• Diagnosis and early warning signals
Routine lab surveillance with intensification before
epidemic season
• Environmental monitoring
• Epidemic prone disease monitoring
• Proper collection, transport and storage of samples
• Reporting of results
Establishing laboratory support
for public health surveillance

21. E P I D E M I C A L E R T A N D R E S P O N S E
Laboratory Training for Field Epidemiologists
Intermediate level objectives
• Diagnosis and early warning signal
• Epidemic preparedness, response and capacity building
In addition to activities at peripheral level, strengthen
surveillance through:
• Supplies and logistics support
• Networking of laboratories, feedback and feed forward
• Monitoring, supervision
• Outbreak investigation, epi-lab coordination
Establishing laboratory support
for public health surveillance

22. E P I D E M I C A L E R T A N D R E S P O N S E
Laboratory Training for Field Epidemiologists
Referral level objectives
• Confirmation and capacity building
Key activities
• Referral investigations
• Outbreak investigation
• Development of guidelines
• Quality assurance program, bio-safety and waste management
• Training, monitoring, supervision and feedback
Establishing laboratory support
for public health surveillance

23. E P I D E M I C A L E R T A N D R E S P O N S E
Laboratory Training for Field Epidemiologists
Surveillance: Lab functions
Confirmation of etiology to resolve syndromic presentation
Data intelligence for:
• Antimicrobial resistance monitoring
• Emergence of unusual isolates
• Detection of new pathogens
• Sero-surveillance

24. E P I D E M I C A L E R T A N D R E S P O N S E
Laboratory Training for Field Epidemiologists
Outbreak detection within the laboratory
Tracing spread through typing and characterization
Detection of carriers and natural foci of infection
Determine the end of an outbreak
Determine elimination or eradication of disease
Surveillance: Lab functions

25. E P I D E M I C A L E R T A N D R E S P O N S E
Laboratory Training for Field Epidemiologists
Surveillance: Lab & epi functions
Outbreak detection and investigation
Develop case definition; determine case management
Environmental monitoring
Understand the natural history of disease
Evaluate interventions
Monitor progress towards control
Develop immunization strategies
Prevalence studies

26. E P I D E M I C A L E R T A N D R E S P O N S E
Laboratory Training for Field Epidemiologists
Public health and clinical labs
Public health laboratories
• Belong to the public sector
• Are involved in public health
• Participate in surveillance
Clinical laboratories
• May be public or private
• Involved in management of patients
• May participate in public health surveillance (e.g. laboratory
reporting)

27. E P I D E M I C A L E R T A N D R E S P O N S E
Laboratory Training for Field Epidemiologists
Developed by the Department of Epidemic and
Pandemic Alert and Response of the World Health
Organization with assistance from:
European Program for Intervention
Epidemiology Training
Canadian Field Epidemiology Program
Thailand Ministry of Health
Institut Pasteur
Role of laboratory in surveillance