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 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 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.Seasonal influenza surveillance b.Avian influenza surveillance c.Pandemic influenza surveillance d.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

Source: WHO Global Influenza Surveillance Network. 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 3.Meet minimum core capacities:  Surveillance  Response  Points of entry Meeting of IHR Member States

How do we accomplish all of these objectives with one surveillance system? ? ? ? ? ? ? U.S. Centers for Disease Control and Prevention

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 SARI- Severe Acute Respiratory Infection ILI- Influenza-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 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

Deaths Hospitalized SARI due to Influenza Influenza resulting in ILI managed in the outpatient department Influenza that is not medically attended Distribution of Influenza within the Population

Epidemiologic Data Defines Influenza Burden of Disease Lower respiratory illness (often SARI) is 2 nd 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 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  Hotline  Local Health Department  Other coordinating bodies Response mechanism Reporting and response are pre-requisites! H5? H7? SARS? Other?

Trigger Criteria Trigger- U nusual 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 This file has been released into the public domain by the copyright holder,

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 aryForm07.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 Smallpox Poliomyelitis, wild-type Human influenza, new sub-type SARS Other Events Potentially Notifiable 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

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

Photo: Joshua Mott, CDC References and Resources WHO case definitions for human infections with influenza A(H5N1) virus. 29 Aug ase/avian_influenza/guideli nes/case_definition2006_0 8_29/en/index.html ase/avian_influenza/guideli nes/case_definition2006_0 8_29/en/index.html

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