SEARO –CSR Early Warning and Surveillance System Module Computerized EWAR systems

SEARO –CSR Early Warning and Surveillance System Module Surveillance system EWAR Event basedCase based Report signal Report signal Outbreak investigation Evaluation Introduction to surveillance Role of IHR EWAR Structure, Prioritization of diseases, Case definitions Signal generation and verification GIS System evaluation Outbreak investigation Alert Routine weekly, monthly and quarterly reporting

SEARO –CSR Early Warning and Surveillance System Module Objectives of this lecture To describe the structure of EWAR systems applied to computer applications, To define the meaning of alert signals and give an overview of the methods used to calculate thresholds To present examples of existing EWAR systems in national and international context.

SEARO –CSR Early Warning and Surveillance System Module Function of a surveillance system aiming to detect any abnormal phenomenon that will trigger prompt public health interventions Definition Structure Computer based EWAR systems Signals Threshold calculation overview EWAR examples Early Warning

SEARO –CSR Early Warning and Surveillance System Module Early warning and response Definition Structure Computer based EWAR systems Signals Threshold calculation overview EWAR examples

SEARO –CSR Early Warning and Surveillance System Module The components of a computerized EWARN System Data collection –Data entry –Data import from an existing system Data analysis Generation of signals Presentation of results Generation of reports Definition Structure Computer based EWAR systems Signals Threshold calculation overview EWAR examples

SEARO –CSR Early Warning and Surveillance System Module Computerized EWAR systems Standardization of: –Data collection –Data flow –Data exchange Better data quality Faster data availability Definition Structure Computer based EWAR systems Signals Threshold calculation overview EWAR examples

SEARO –CSR Early Warning and Surveillance System Module Automated report generation with updated data Customized reports –Optimized presentation Interactive browsing/exploration of data Information on demand Definition Structure Computer based EWAR systems Signals Threshold calculation overview EWAR examples Computerized EWAR systems Easier, faster feedback

SEARO –CSR Early Warning and Surveillance System Module Improved and faster analysis, Larger datasets can be analysed, Use of different algorithms, Automated signal generation, and flagging of situation for immediate attention. Definition Structure Computer based EWAR systems Signals Threshold calculation overview EWAR examples Computerized EWAR systems Rapid response

SEARO –CSR Early Warning and Surveillance System Module Signals A signal is something that could indicate the impending occurrence of an event. (WHO SEARO Early Warning and Response to Outbreaks and other Public Health Events: A Guide) Definition Structure Computer based EWAR systems Signals Threshold calculation overview EWAR examples

SEARO –CSR Early Warning and Surveillance System Module Nature of the health event –Massive and sudden Common point source (Salmonellosis…) –Diffuse and progressive Person to person (Shigellosis, Hepatitis…) –Sporadic and widespread Persistent common source (salmonella, listeria in food chain, legionella…) Definition Structure Computer based EWAR systems Signals Threshold calculation overview EWAR examples

SEARO –CSR Early Warning and Surveillance System Module EWARN – Thresholds Local epidemiology of the disease Endemic/hyper-endemic/epidemic Seasonal/non seasonal Rare/common Outbreak distribution type (eg. point source rather than persistent or propagated source) Definition Structure Computer based EWAR systems Signals Threshold calculation overview EWAR examples

SEARO –CSR Early Warning and Surveillance System Module Thresholds can be based on Absolute numbers Rates Relative changes over time Definition Structure Computer based EWAR systems Signals Threshold calculation overview EWAR examples

SEARO –CSR Early Warning and Surveillance System Module Methods based on the number of cases of disease (predefined thresholds) Number of cases –One case of measles (Refugee Camp) Number of cases / population / time –Epidemic threshold: 10 Cases of meningitis / /week (Meningitis belt) Definition Structure Computer based EWAR systems Signals Threshold calculation overview EWAR examples

SEARO –CSR Early Warning and Surveillance System Module Predefined Thresholds + - Easy to interpret and to communicate How to deal with seasonal patterns and trends No historical data needed Increase from 2 to 4 the same like 2000 to 4000? Definition Structure Computer based EWAR systems Signals Threshold calculation overview EWAR examples

SEARO –CSR Early Warning and Surveillance System Module Methods based on c hanges over time Increase of cases –Cases in week x higher than mean for last 4 weeks Doubling of cases over a given time period –Doubling of cases over 3 weeks period (Meningitis belt – small districts) Definition Structure Computer based EWAR systems Signals Threshold calculation overview EWAR examples

SEARO –CSR Early Warning and Surveillance System Module Presentation of surveillance EWAR data crude data

SEARO –CSR Early Warning and Surveillance System Module Signal Secular trend Seasonal factor Residual signal Presentation of surveillance EWAR data time series

SEARO –CSR Early Warning and Surveillance System Module For weekly data: a smoothing average of 5 to 15 weeks highlights the seasonality Presentation of surveillance EWAR data seasonal pattern

SEARO –CSR Early Warning and Surveillance System Module For weekly data: smoothing average of 52 weeks highlights the trend Presentation of surveillance EWAR data long term pattern

SEARO –CSR Early Warning and Surveillance System Module Examples of early warning systems Definition Structure Computer based EWAR systems Signals Threshold calculation overview EWAR examples

SEARO –CSR Early Warning and Surveillance System Module Meningitis in sub-saharan Africa Definition Structure Computer based EWAR systems Signals Threshold calculation overview EWAR examples

SEARO –CSR Early Warning and Surveillance System Module Objectives of the meningitis surveillance system Timely detection of outbreaks Immediate confirmation of the outbreak Identification of pathogen and serogroup Rapid response –Vaccination –Proper case management Definition Structure Computer based EWAR systems Signals Threshold calculation overview EWAR examples

SEARO –CSR Early Warning and Surveillance System Module Meningitis surveillance system Meningitis one out of 10 diseases Integrated Disease Surveillance Weekly notifications aggregated data to district level –Suspected cases –Deaths –District  National Level  Region (Burkina Faso) Immediate reporting when district crossed threshold Zero reporting Definition Structure Computer based EWAR systems Signals Threshold calculation overview EWAR examples

SEARO –CSR Early Warning and Surveillance System Module Thresholds for meningitis in the meningitis belt Districts > population Incidence (weekly) Districts < population Cases (per week) Doubling of cases Alert >= 5/ Epidemic >=10/ Alert >= 2 Epidemic >= 5 Definition Structure Computer based EWAR systems Signals Threshold calculation overview EWAR examples

SEARO –CSR Early Warning and Surveillance System Module Thresholds for meningitis in the meningitis belt Alert / Epidemic → Epidemic /Epidemic

SEARO –CSR Early Warning and Surveillance System Module Crossing thresholds actions to be taken Alert threshold vs Epidemic threshold Definition Structure Computer based EWAR systems Signals Threshold calculation overview EWAR examples

SEARO –CSR Early Warning and Surveillance System Module Objectives of the EWAR and Reporting System for Meningitis 1.Combine timely information from the whole region. 2.Share information across the region, 3.Flag districts in alert or epidemics, 4.Give an estimate of persons at risk, and 5.Give an overview of circulating sero-groups. Definition Structure Computer based EWAR systems Signals Threshold calculation overview EWAR examples

SEARO –CSR Early Warning and Surveillance System Module Definition Structure Computer based EWAR systems Signals Threshold calculation overview EWAR examples

SEARO –CSR Early Warning and Surveillance System Module CountryIndicatorDistricts inCompletnessPathogens CasesDeaths CFR % Aler t EpidWeeksDistricts Weeks % Nm.AW135 Othe r Nm Pneu m Hib Benin / Burkina Faso / Côte d ’ Ivoire / Ethiopie ND Ghana / Mali / Niger / Tchad / Togo / Total WHO World Health Organization MDSC Multi Disease Surveillance Center Comments Laboratory data for Niger updated for week 37. No relevant change of the situation compared to last week. I. Synthesis of the epidemiologic situation up (week to )

SEARO –CSR Early Warning and Surveillance System Module Example of map showing districts in alert and epidemic in the meningitis belt

SEARO –CSR Early Warning and Surveillance System Module Summary of alerts and epidemics by country

SEARO –CSR Early Warning and Surveillance System Module Districts of one country currently affected

SEARO –CSR Early Warning and Surveillance System Module Detailed Information for one country - I Definition Structure Computer based EWAR systems Signals Threshold calculation overview EWAR examples

SEARO –CSR Early Warning and Surveillance System Module Detailed Information for one country - II Definition Structure Computer based EWAR systems Signals Threshold calculation overview EWAR examples

SEARO –CSR Early Warning and Surveillance System Module Olympic Games Athens 2004

SEARO –CSR Early Warning and Surveillance System Module Enhanced Surveillance Mandatory System Syndromic Systems Sentinel System Laboratory System Hospitals, Physicians, Olympic sites Different regions/districts Definition Structure Computer based EWAR systems Signals Threshold calculation overview EWAR examples Daily reporting including zero reporting

SEARO –CSR Early Warning and Surveillance System Module Computer Application EWARN and reporting Automated output generation –Daily report –Detailed internal report –Signal lists (Alerts) Definition Structure Computer based EWAR systems Signals Threshold calculation overview EWAR examples Embedded in an interactive HTML system –Signal tracking –Alert tracking

SEARO –CSR Early Warning and Surveillance System Module Global and disease specific outputs - Athens Information on selected diseases / syndromes Definition Structure Computer based EWAR systems Signals Threshold calculation overview EWAR examples

SEARO –CSR Early Warning and Surveillance System Module Signals Two statistical methods for threshold calculation were applied: –Poisson test –Binominal test Colour coding –yellow p-value<= 0.05, red p-value<=0.01 For syndromic surveillance system Olympic hospitals only –Additional tests applied Definition Structure Computer based EWAR systems Signals Threshold calculation overview EWAR examples

SEARO –CSR Early Warning and Surveillance System Module Definition Structure Computer based EWAR systems Signals Threshold calculation overview EWAR examples Disease specific outputs - Athens Graphs Tables

SEARO –CSR Early Warning and Surveillance System Module Signal lists of all diseases / syndromes with statistical tests result (p-value) below the predefined thresholds Signals Olympic Game Hospitals Signals laboratory system Definition Structure Computer based EWAR systems Signals Threshold calculation overview EWAR examples Disease specific outputs - Athens

SEARO –CSR Early Warning and Surveillance System Module Signal tracking system Generation of printable lists for the daily meeting Self updating Excel Database for signal tracking Definition Structure Computer based EWAR systems Signals Threshold calculation overview EWAR examples

SEARO –CSR Early Warning and Surveillance System Module Question Time 1.Why would you need to define thresholds for your diseases under EWAR surveillance? 2.What is the limit of predefined thresholds? 3.Based on your current knowledge what would you say the strengths/weaknesses of the EWAR systems implemented in Africa and Athens?