Event based surveillance systems Alicia Barrasa Introductory course 2012 Lazareto, Menorca, Spain

Infectious diseases Arise from many different pathogens: viruses, bacteria, parasites Spread in many different species: humans, insects, domestic and wild animals, aquatic animals and sometimes breach barrier between animal and humans (70% of emerging infections arise from animal population) Take many different routes of transmission: direct contact, vectors, food, environmental Affect all populations in all regions of the world

Emerging and Re-emerging infectious diseases A(H1N1)v

Accidental and deliberate release of infectious agents Increased research, biotechnology is widely available Increased risk for accidental release (e.g. SARS 2004 from laboratory) World tensions remain and the deliberate release of infectious agents is no longer a remote threat.

International Health Regulation 1374Venice Quarantine for Plague 1851Paris1st International Sanitary Conference 1947GenevaWHO Epidemiological Information Service 1951GenevaInternational Sanitary Regulations 1969GenevaInternational Health Regulations 2004Regional consultations Nov 2004 GenevaIntergovernmental Working Group meeting Feb 2005 GenevaIntergovernmental Working Group meeting May 2005GenevaRevised IHR, World Health Assembly adopted

4 diseases that always have to be notified polio (wild type virus), smallpox, human influenza caused by a novel virus, SARS. Diseases that always lead to the use of the algorithm : cholera, pneumonique plague, yellow fever, VHF (Ebola, Lassa, Marburg), WNF, meningitis, others *Q1: serious graves repercussions for public health? Q2: unusual or unexpected? Q3: risk of international spread? Q4: risk of travel or traffic restrictions? Insufficient information : re-evaluate IHR Decision Instrument

International Health Regulation To decide on need for notification any public health event can be assessed by the criteria 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 travel restrictions ? Obligation to establish core capacities: Surveillance Response

Epidemic Intelligence Definition –The systematic collection and collation of information from a variety of sources, usually in real-time, which is then verified and analysed and, if necessary, activates response Objective –to speed up detection of potential health threats and allow timely response

Epidemic Intelligence - ECDC Establish procedures for the identification of emerging health threats in cooperation with MS Identify, assess and communicate current and emerging communicable disease threats Inform EC and MS about emerging health threats requiring their immediate attention Communication on emerging health threats, including to the public

Surveillance is Information for action

Epidemic Intelligence Data Events Collect Analyse Interpret Screen/collect Filter Validate Assess Investigate Signal Response Public health Alert Event monitoringSurveillance systems Event-based surveillanceIndicator-based surveillance

Indicator based Surveillance Surveillance systems Ongoing and systematic –Collection and analysis of data –Interpretation and dissemination of results related to health events of interest For action –Describe diseases –Outbreak detection –Monitor changes /interventions –Provide evidence for policy making –Generate hypothesis

Event based Surveillance Organized and rapid capture of information about events that are a potential risk to public health: Events related to the occurrence to the disease in humans (clusters, unusual patterns, unexpected deaths…) Events related to potential exposures (diseases in animals, contaminated food or water, environmental hazards…) Need confirmation

Indicator vs event based Indicator basedEvent based Definitions - Clinical presentation - Characteristics of people - Laboratory criteria - Specific -...events that are a potential risk -...unusual events in the community - Sensitive Timeliness - Weekly / monthly (some may be immediate) - Possible delay between identification and notification - All events should be reported to the system immediately - Real time

Indicator vs event based Indicator basedEvent based Actors - Involved in the system- Might not know Reporting structure - Clearly defined - Reporting forms - Reporting dates - Teams to analyse data at regular intervals - No predefined structure - Reporting forms flexible for quali and quantitative data - At any time - Teams to confirm evens and prepare the response

Indicator vs event based Indicator basedEvent based Trigger for action - a pre-defined thresholds- a confirmed event Response - depends on the delay between identification, data collection and analysis - depends on the confirmation of the event, but ideally is immediate

Epidemic Intelligence Data Events Collect Analyse Interpret Screen/collect Filter Validate Assess Investigate Signal Response Public health Alert Event monitoringSurveillance systems Event-based surveillanceIndicator-based surveillance

Epidemic Intelligence - ECDC

The process of Epidemic Intelligence 1.Screening/collecting 2.Filtering 3.Validating 4.Analysis 5.Assessment 6.Documentation 7.Communication

Screening / Collecting: Monitoring known threats and detecting new threats by screening a virtually unlimited amount of information.

web-based early warning systems Sophisticated applications able to gather, filter and classify web-based information for public health purposes AdvantagesDisadvantages Automatic systems little or no human intervention near real time information False positive component, duplication, overload for analysts Moderated systems rely on human moderation analysts reduce redundancy and false positive Time delay, human selection bias

Filtering: The objective of filtering is to decide which information detected through screening might be potential public health events of National, European or international concern. Early detection

Validation: This is the process of confirming the accuracy and credibility of information received from non-official sources (unverified information). Early detection Identification of signals

Analysis: Initial evaluation based on preliminary info available in terms of likelihood and of possible human public health impact Risk Assessment

Documentation: Logging information and actions taken during the EI process from the beginning is a crucial action to analyse the ongoing situation and to trace back all the steps

Communication: To public/media and to scientific community about findings and assessment of potential public health events detected and investigated

Epidemic Intelligence - ECDC

A small summary Indicator and event based systems are tools for PH Surveillance event based systems have already been successfully used The challenge: confirmation of the events

Epidemic Intelligence at ECDC 24/7 Screening of news from different sources Round table –Daily threat assessment –Daily & weekly reports –Communication Risk assessment Response to outbreaks

WHO. The revision of the International Health Regulations. Wkly Epidemiol Rec 1996; 71: WHO. Revision of the International Health Regulations: progress report, January Wkly Epidemiol Rec 1998; 73: 17-9 Paquet C, Coulombier D, Kaiser R, Ciotti M. Epidemic intelligence: a new framework for strengthening disease surveillance in Europe. Euro Surveill. 2006;11(12):665 WHO. A guide to establishing event-based surveillance basedsurv.pdf … to know more …

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