Transcript Surveillance for Human and Avian Influenza in

Influenza Surveillance
U.S. Centers for Disease Control and Prevention
Learning Objectives
• Describe distinctions between seasonal, avian,
and pandemic influenza surveillance among
humans
• Describe seasonal influenza surveillance as a
framework for avian and pandemic influenza
surveillance
• Describe standard case definitions for
surveillance
Learning Objectives
• Describe epidemiologic data collection
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elements
Describe ways to enhance local surveillance
following a poultry outbreak of Highly
Pathogenic Avian Influenza (HPAI) or
following identification of human cases of
influenza A (H5N1) virus infection
Describe alert and response trigger criteria for
early warning surveillance
Outline
• Seasonal, avian, and pandemic influenza
components
• Surveillance system objectives
• Components of an influenza surveillance
system
Sentinel-site seasonal influenza/respiratory disease
surveillance
Broad-based early warning systems
• Enhancing the early warning network
• WHO reporting requirements
Seasonal, Avian, and Pandemic
Influenza
Review
Definition of Terms
• Seasonal (human) Influenza
Endemic
Strain varies slightly year to year
• Avian Influenza
May be reservoir for completely new strains in humans
Can be Highly Pathogenic Avian Influenza (HPAI)
• Pandemic Influenza
Global epidemic of new influenza A subtype in humans
Influenza Surveillance System
Objectives
Seasonal Influenza
Surveillance System Objectives
• Describe epidemiology of seasonal influenza and burden of
disease
• Provide isolates for identification of viruses and monitoring of
resistance
• Provide country specific data for program planning and
preparedness
• Serve as an early warning for outbreaks of novel influenza in
humans or the circulation of a potentially new pandemic
pathogen
Expanding Surveillance Priorities
Seasonal Influenza
• Characterize viruses, describe seasonality, high risk
groups, epidemiology
• Assess burden of disease
Human Infection with Avian Influenza Viruses
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Treat appropriately and prevent transmission
Implement animal control
Investigate for additional cases
Contain if represents an emerging pandemic
Expanding Surveillance Priorities,
continued
Pandemic Influenza - early phases
• Recognize emergence early enough to contain or slow
epidemic
Pandemic Influenza - later phases
• Monitor distribution and epidemiology of cases, virus
characteristics (including resistance), resource needs
• Assess the impact of prevention and control activities
Priorities will change over the course of a
pandemic
Review Question #1
Providing isolates for identification of viruses and
monitoring of resistance is an objective of which
type of surveillance?
a.
b.
c.
d.
Seasonal influenza surveillance
Avian influenza surveillance
Pandemic influenza surveillance
All of the above.
Answer: d.
WHO Laboratory Influenza Surveillance
Objectives
Global Influenza Surveillance Network (GISN):
• Monitor influenza viruses and make influenza
vaccine composition recommendations
• Provide prototype influenza vaccine strains and
standardized reagents for vaccine production and
testing
• Detect, characterize, and track samples of
unusual influenza strains
WHO Global
Influenza Surveillance Network
Source: WHO Global Influenza Surveillance Network.
WHO GISN Limitations in the
Current Context
Developed before emergence of H5N1
Unlikely to detect early stages of pandemic
Incomplete surveillance
Lack of virologic data from many places
Very limited epidemiologic data
Epidemiology, burden, and patterns of
transmission unknown in tropics and most of
subtropics
International Health Regulations
Member countries must:
1. Notify WHO of any potential
Public Health Emergency of
International Concern (PHEIC)
2. Enhance events management :
improve alert and response actions
Meeting of IHR Member States
http://www.who.int/csr/ihr/en/
3. Meet minimum core capacities:
 Surveillance
 Response
 Points of entry
How do we accomplish all of these
objectives with one surveillance system?
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U.S. Centers for Disease Control and Prevention
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Components of an Influenza
Surveillance System
1. Sentinel Site Surveillance (seasonal and
other respiratory pathogens)
2. Early Warning and Event-based
Surveillance (novel influenza viruses or
emerging pandemic)
Meeting Influenza Surveillance Needs
• National sentinel surveillance systems for
seasonal influenza
Well-chosen sentinel sites
Collection of virologic and epidemiologic data
• Capability for early response
• Broad applicability of system
Two Necessary Surveillance Activities
1. Sentinel Surveillance
National seasonal influenza surveillance
systems
Syndromic surveillance for:
• Severe Acute Respiratory Infection (SARI)
• Possibly Influenza-like-Illness (ILI)
2. Early Warning System
PART 1.
Seasonal
Influenza
Surveillance:
Infrastructure of
Sentinel System
U.S. Centers for Disease Control and Prevention
Review Question #2
What two activities are needed to meet the influenza
surveillance needs?
Answer: 1. Establish sentinel surveillance for
seasonal influenza, to include syndromic
surveillance for severe acute respiratory
infection and influenza-like illness.
2. Establishment of an early warning system for
outbreaks of Influenza A(H5N1) in humans or the
emergence of a new pandemic virus
Choosing Surveillance Sites
Site choice issues:
• Geographic and demographic representativeness of patient
population
• Feasibility/ease of data collection
• Feasibility of specimen collection, storage and transport
• Staff acceptance of surveillance system
• Ability to define the population under surveillance
• Timeliness
• Cost
• Flexibility
• Political considerations
Optimal sites may be determined by utilization patterns in a country or
area
Site Characteristics
Are specimen transport logistics feasible?
Is there staff acceptance?
Do they represent population?
Can we derive burden of disease estimates?
Choose institutions based their likelihood of
success
Respiratory Infection Terms
• SARISevere Acute Respiratory Infection
• ILIInfluenza-like-Illness
• Burden of Disease Estimate –
The impact of a health problem in a geographical
area as measured by morbidity, mortality and
possibly financial costs
SARI Case Definition
Persons over 5 Years Old
Moderate-to-severe acute lower respiratory
tract illness consisting of the following:
• Temperature > 38ºC AND
• Cough or sore throat AND
• Shortness of breath or difficulty
breathing AND
• Requiring hospitalization
SARI Case Definition
Persons less than 5 Years Old
Pneumonia
Any child 2 months to 5 years of age with cough or
difficult breathing and:
• breathing faster than 50 breaths / minute (2 – 12
months of age)
• breathing faster than 40 breaths / minute ( 1 – 5
years of age)
Infants less than 2 months with fast breathing 60 breaths
or more per minute are referred for serious bacterial
infection.
SARI Case Definition
Persons less than 5 Years Old
Severe Pneumonia
Any child 2 months to 11 months of age with cough
or difficulty breathing and any of the following signs:
• Unable to drink or breastfeed
• Vomits everything
• Convulsions
• Lethargic or unconscious
• Or chest indrawing or stridor in a calm child
AND
• Requiring hospital admission
Influenza-Like-Illness (ILI)
in Ambulatory Patients
ILI Definition: Acute illness with fever > 38°C,
and cough or sore throat
Ambulatory patient surveillance would:
• Increase influenza epidemiology data
• Enable monitoring of ILI trends
Increases in ILI cases may indicate an epidemic
Data Collection from SARI Cases
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Name
Age
Address/location
Gender
Date of onset
Clinical signs and symptoms
Clinical specimens for testing
Outcome
Unique identifier to link to laboratory specimen
“Trigger criteria” and epidemiologic links
Feedback and Positive Reinforcement
• Laboratory results
• Quarterly reports
• Influenza notifications to providers
• Credit for refresher trainings
• Regular surveys and site visits
Distribution of
Influenza
within the
Population
Deaths
Hospitalized
SARI due to
Influenza
Influenza resulting in
ILI managed in the
outpatient
department
Influenza that is not
medically attended
Epidemiologic Data Defines
Influenza Burden of Disease
• Lower respiratory illness (often SARI)
is 2nd leading cause of death
• Significant unknown portion attributable
to influenza
• Burden data useful to for policy makers
Directly Estimate Burden of Disease
• Assess catchment area for a sentinel site
Health Utilization Surveys
• Use SARI and/or ILI case definition and
laboratory testing of all or a random sample
of cases
• Estimate rates of SARI and/or ILI and
laboratory-confirmed influenza for catchment
area
Influenza Surveillance in the
Context of an Existing Disease
Surveillance System
• Embedded sentinel system
High quality data from a few select sites
• Integrate SARI surveillance into national
reporting
• Identify “epidemic thresholds”
Sentinel Surveillance to Enhance
Early Warning
1. A logistical network for specimen collection
and transport
2. Laboratory capacity for specimen testing
3. A reporting system
4. Trained epidemiologist to analyze data and
assess risk
5. A system for responding to unusual events
recognized in the surveillance data
Value of Sentinel Surveillance for
Pandemic Monitoring
• Will use existing, routine sources of
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information
Must be useful to other member states to track
spread of virus
Basic components may include
Proportion of hospitalizations due to SARI
SARI case-fatality proportion
Review Question #3
What are the goals of sentinel surveillance for
influenza? (Choose all that apply)
a. To be a basis for influenza burden of disease estimates
b. To detect the occurrence of a novel strain of influenza
c. To provide the infrastructure for early warning and
pandemic monitoring systems
d. To provide isolates for identification of viruses and
monitoring of resistance
Answer:
a, c, d, and e
PART 2
Building an Early
Warning System
• Detect Novel
Influenza Virus
Infection
• Provide Pandemic
Early Warning
U.S. Centers for Disease Control and Prevention
Integration with IHR (2005)
• From three diseases to all public health threats
• Key functions involve detection, verification,
assessment, information sharing, response
• All essential to avian/pandemic influenza
Pandemic Warning Systems
Requirements
• Triggers for immediate reporting and
response
• Broad-based education program
• Infrastructure
Considerations for an
Early Warning System
Surveillance for PHEICs
H5N1 best candidate for next pandemic strain,
but no guarantee
True goal is to build a pandemic early warning
system (not an H5N1 warning system per se)
Detecting influenza A (H5N1) pandemic
Only a small fraction of cases may have linkage
to poultry
Early Warning System
Requirements
• Broad based recognition of “trigger criteria”
• Trained staff that can assess risk and
determine response
• Mechanisms for reporting & detection H5?
Hotline
Local Health Department
Other coordinating bodies
• Response mechanism
• Reporting and response
are pre-requisites!
H7?
Other?
SARS?
Trigger Criteria
TriggerUnusual cases or events that elevate the index
of suspicion of a possible human infection
with a novel influenza virus or signal the
possible emergence of a new pandemic
respiratory pathogen
Trigger Criteria
12
10
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Cases
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0
J F M A M J J A S O N D
This file has been released into the public domain by the copyright holder,
http://www.nlm.nih.gov/medlineplus/ency/images/ency/fullsize/17276.jpg
Poultry-to-Human Triggers
• Any case meeting WHO suspect,
probable, or confirmed case
definition
• SARI cases in workers in
poultry industry
• Association with sick or dying
poultry or wild birds
• History of travel within the last
10 days to a specific area or
region known to have currently
circulating Avian Influenza
Photo: Tony Mounts, CDC
Human-to-Human Triggers
• Cases in health care workers who care for patients
with SARI or pneumonia
• Clusters of 2 or more SARI cases in a 2 week
period
In a family or household
In a small geographic area
Among persons with a social or occupational
connection
• Increases in cases at a site compared
to the same time in previous years
• Change in the epidemiology of cases
Other Triggers for Investigation
• Poultry events: excessive deaths
• Rumors from informal data sources
 News media
 Information hotlines
Photo: Diane Gross, CDC
Rapid Response
• All trigger reports
deserve investigation
• Collect data and
specimens for trigger
cases
• Use influenza as
‘case study’ for
outbreak
preparedness
U.S. Centers for Disease Control and Prevention
Review Question #4
Which of the following would be considered trigger criteria
for an investigation of influenza A(H5N1) occurrence?
a. Any case meeting WHO suspect, probable or confirmed case
definition for influenza A(H5N1)
b.SARI cases in association with sick or dying poultry or wild birds
which is not occupational
c. Cases in health care workers who care for patients with SARI or
pneumonia
d.Excessive poultry deaths
e. All of the above
Answer: e. All of these are trigger criteria!
Review Question #5
What is the goal of an early warning system?
Answer: The timely detection of cases, clusters,
or events with pandemic potential (of any
pathogen)
Enhancing the Early Warning
Network
Photo: Diane Gross, CDC
Education /Awareness and Feedback
• Train healthcare providers
Include non-mainstream providers and pharmacists
• Educate media
Regular training refreshers/public education
• Nationwide public health education and awareness
• Feedback
Agriculture Links
• Link each administrative level
Create formal 2-way communication
mechanisms
• Cross-reporting and investigation
of animal outbreaks
Search for human cases and
implement appropriate response
• Report human cases to the
Ministry of Agriculture
May signal unrecognized poultry
outbreak
Photo: Diane Gross, CDC
Enhancing Surveillance
During an Outbreak
• Active case finding among exposed
• Door-to-door surveys
• Self-Reporting
Instruct community to be vigilant, looking for
symptoms for 1 week after last exposure to avian
influenza-infected or exposed birds
Include risk reduction messages
Enhancing Surveillance
During an Outbreak, cont.
• Expand involvement
Local hospitals, other providers
Recruit private practices, nongovernmental
organizations (NGOs), religious institutions, and
schools
Include training on reporting procedures
• Actively involve village health monitors
• Telephone reporting hotlines
Successful Event Detection,
Assessment, and Response
Sensitized network of informants
Defined mechanisms for reporting
Trained staff who can assess risk, raise alerts, and
undertake epidemiologic investigations
News & rumor/informal report monitoring
Feedback on results of the investigation
Positive reinforcement for reporting of triggers
Accurate data on the report, response, and
conclusion
Procedures for informing the media and the public
Utility of Early Warning or Sentinel
Site Surveillance beyond Influenza
Create a sustainable, cost-effective system to:
• Identify other events of public health significance
• Produce informative data about other lower respiratory
disease
• Remain in place after H5N1 interest wanes
Review Question #6
Name 2 ways to enhance early warning
networks
Example answers (more possible):
Forming linkages to agricultural agencies
Conducting active case finding during outbreaks,
such as door-to-door surveys
Conducting ongoing education and awareness
efforts
WHO Reporting Requirements
WHO H5N1 Reporting Case Definitions
• Goal
Standardize reporting of cases
Comparability of data
• Context
Countries with H5N1 or travelers
Not intended to be used as a screening
criteria for laboratory testing or
epidemiologic investigation
WHO H5N1 Case Definitions
Person under investigation:
Person whom public health authorities have
decided to investigate for possible H5N1
infection
Suspected H5N1 case:
A person presenting with unexplained acute
lower respiratory illness with fever (>38 ºC)
and cough, shortness of breath or difficulty
breathing AND
Epidemiologic linkage to exposure
Source: WHO case definitions for human infections with influenza A(H5N1) virus
What is a WHO H5N1
Epidemiologic Link?
• Close contact with a suspected, probable, or
confirmed H5N1 case
• Exposure to poultry or wild birds, their remains, or to
environments contaminated by their feces in an area
where H5N1 outbreaks in humans or poultry have
been suspected or confirmed in the last month
• Consumption of raw or undercooked poultry products
where H5N1 outbreaks in humans or poultry have
been suspected or confirmed in the last month
Source: WHO case definitions for human infections with influenza A(H5N1) virus
What is a WHO Suspect H5N1
Epidemiologic Link? cont.
• Contact with a confirmed H5N1 infected
animal other than poultry or wild birds
• Handling samples suspected of containing
H5N1 virus in a laboratory or other setting
Source: WHO case definitions for human infections with influenza A(H5N1) virus
WHO H5N1 Case Definition
Probable Case
Notify WHO
• Suspected H5N1 case AND
Abnormal CXR/respiratory failure; or
Lab test positive for influenza A infection,
but insufficient laboratory evidence for
H5N1
• A person dying of an unexplained acute
respiratory illness with an epidemiologic link
to a probable or confirmed H5N1 case
WHO H5N1 Case Definition
Confirmed Case
Notify WHO
• A person meeting the criteria for suspect or probable
case and
• One of the following positive results from laboratory
testing:
 Isolation of an H5N1 virus
 Positive H5 PCR results for 2 different PCR targets
 At least 4-fold rise in H5N1 neutralizing antibody based on
acute and convalescent serum specimens
 A microneutralization antibody titer for H5N1 of >1:80 in
a single serum specimen collected at day 14 or later after
symptom onset and a positive result using a different
serological assay
National Reporting
• Immediate reporting of suspected, probable and
confirmed H5N1 cases and clusters to national public
health authorities
Use standard reporting forms on WHO website
http://www.who.int/csr/disease/avian_influenza/guidelines/Summary
Form07.pdf
Weekly summarization of cases, even if there are none
(zero reporting)
• Information should be shared with all relevant partners
inside the country, especially the animal health authorities
• Central analysis and response
International Reporting
IHR (2005)
Member countries must:
• Notify WHO of any potential PHEIC
• Enhance their events management – especially
alert and response actions
• Meet minimum core capacities:
surveillance, response, and screening at
points of entry
Local, intermediate, and national requirements
Assessing the Threat under IHR
PHEIC
Always Notifiable
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Smallpox
Poliomyelitis, wild-type
Human influenza, new sub-type
SARS
Other Events Potentially Notifiable
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Examples: cholera, pneumonic plague, yellow fever, viral
hemorrhagic fever, and West Nile fever
Other biologic, radiological, or chemical events may fit the
decision algorithm and be reportable
Criteria for Notification
• Is the public health impact of the event serious?
• Is the event unusual or unexpected?
• Is there a significant risk of international spread?
• Is there a significant risk of international
travel or trade restrictions?
WHO makes final determination whether
an incident is a PHEIC
Data/information sources for early
warning and IHR
Indicator-based surveillance
(discrete variables)
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“Classical surveillance”
Case no. (diseases, conditions, syndromes)
Laboratory results
Environmental measurements
Etc.
- e.g. SARI
NOT
mutually
exclusive
Event-based surveillance
(unstructured information)
Signal
- e.g. Trigger Criteria
- Media reports
- Rumours
-Etc.
(unusual health event / public health
risk)
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Signal confirmation
Alert
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Response
Risk assessment
- At all levels
- Intuitive and/or structured
- Reiterative
Review Question #7
True or False:
Human influenza caused by a new subtype is
notifiable under IHR
Answer: True. The following are always notifiable.
NEW sub-types of human influenza
Smallpox
Poliomyelitis, wild-type
Human influenza, novel sub-type
SARS
Good sentinel systems can…
• Provide valuable information on seasonality,
epidemiology, virus circulation and burden of
severe disease
• Provide infrastructure for pandemic warning
system
Surveillance for Avian Viruses in
Humans
• Requires alert health care system and must
involve the community
• Early warning surveillance systems are required
for timely recognition, testing, and reporting
• Collaboration between animal and human health
workers is important
Summary
• Requires a broad-based early warning system
for timely recognition, testing, and reporting
• Requires alert health care workers and often
involves the community
• Requires collaboration and cross-notification
between animal and human health workers
References and Resources
• WHO case definitions for
human infections with
influenza A(H5N1) virus.
29 Aug 2006.
http://www.who.int/csr/dise
ase/avian_influenza/guideli
nes/case_definition2006_0
8_29/en/index.html
Photo: Joshua Mott, CDC
Glossary
• Seasonal Influenza
• Avian Influenza
• Pandemic Influenza
• Avian Influenza A (H5N1)
• GISN
• International Health Regulations
• PHEIC
• Sentinel Site Surveillance
• Early Warning & Event-Based Surveillance
• SARI
• ILI
• Burden of Disease Estimate
• Embedded Sentinel System
• Epidemic Threshold
• Signal Events/Trigger Events
• Person under Investigation
• Suspected H5N1 Case
• Probable Case
• WHO H5N1 Epidemiologic Link
• WHO Confirmed H5N1 Case
• Always Notifiable PHEIC
• Potentially Notifiable PHEIC