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Principles of Surveillance Lazareto de Mahón, Menorca, Spain 9 th October 2006 EPIET 2004; Denise Werker EPIET 2005; Suzanne Cotter EPIET 2006; Susan Hahné

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Presentation on theme: "Principles of Surveillance Lazareto de Mahón, Menorca, Spain 9 th October 2006 EPIET 2004; Denise Werker EPIET 2005; Suzanne Cotter EPIET 2006; Susan Hahné"— Presentation transcript:

1 Principles of Surveillance Lazareto de Mahón, Menorca, Spain 9 th October 2006 EPIET 2004; Denise Werker EPIET 2005; Suzanne Cotter EPIET 2006; Susan Hahné

2 Content aim of lecture context, definitions and history of surveillance the process aims of surveillance criteria for undertaking surveillance surveillance versus research steps in setting up surveillance challenges & opportunities summary

3 After the lecture, you should be able to… Define: surveillance its three main components Describe: the contexts / historical perspective of surveillance possible aims criteria for undertaking surveillance the difference between surveillance and research the different steps in setting up surveillance some challenges and opportunities Aim

4 Context (1) Presentations Principles of surveillance Problem-based exercises Secular trends Surveillance –set up surveillance –analytic tools for surveillance –evaluation of surveillance systems Surveillance in EPIET Introductory Course

5 Intervention Epidemiology Surveillance Outbreak investigation Applied epidemiological research Context (2)

6 Control of Communicable Diseases: Tools isolation treatment disinfection & barriers quarantine & surveillance vaccination prophylaxis Context (3)

7 Control of Communicable Diseases: Tools isolation treatment disinfection & barriers quarantine & surveillance vaccination prophylaxis Context (3) Close observation of individuals suspected of incubating serious infectious diseases in order to detect initial symptoms of disease in time to institute treatment and isolation

8 Surveillance n. Close observation, especially of a suspected spy or criminal ORIGIN C 19: from Fr., from sur- 'over' + veiller 'watch' Source: The Concise Oxford Dictionary. Ed. Pearsall J. Oxford University Press, Definition - dictionary

9 Surveillance The continuing scrutiny of all aspects of occurrence and spread of disease that are pertinent to effective control Source: Last JM. A Dictionary of Epidemiology (Second Edition). Oxford University Press 1988, New York. Definition – epidemiology (1)

10 Surveillance Continued watchfulness over the distribution and trends of incidence, through the systematic collection, consolidation and evaluation of morbidity and mortality reports and other relevant data together with the timely and regular dissemination to those who need to know Source: Alexander Langmuir (1910 – 1993) Definition – epidemiology (2)

11 William Farr (1807 – 1883) Superintendent, statistical department, General Register Office, England and Wales Collected, analysed, interpreted vital statistics Plotted rise and fall of epidemics of infectious diseases, identifying associations Disseminated information in weekly, quarterly, and annual reports, medical journals, public press First use for Public Health Action Historical perspective (1)

12 21 st World Health Assembly (1968) Systematic collection of pertinent data Orderly consolidation and evaluation of these data Prompt dissemination of the results to those who need to know " Information for action" Recognition by World Health Organization Historical perspective (2)

13 Health Care SystemPublic Health Authority Event Data Information Intervention Reporting Capture Analysis & Interpretation Real world! … expected changes Dissemination Surveillance is a cyclical process

14 manage contacts of a case detect outbreaks early warning design/change vaccination policy design policy re antimicrobial resistance evaluate interventions to improve them certify elimination / eradication Aims of Surveillance (1) Actions: examples

15 Public Health aims Assess public health status (monitor trends, detect outbreaks) - prevent and control disease Define public health priorities - plan considering impact of hazard, exposure, disease Evaluate public health programmes - make decisions regarding interventions Stimulate or inform research - generate hypotheses, inform methodologie Aims of Surveillance (2)

16 burden of disease (incidence / prevalence) severity, mortality epidemic potential, threat costs, socio-economic impact preventability / opportunities for control public concern and news-worthiness Feasibility costs availability of data Criteria for undertaking surveillance Public Health importance Public Health importance / rationale

17 Surveillance versus Research Surveillance Applies existing knowledge to guide health authorities in the use of known control measures Directly relevant to monitoring and control needs Research Pursues new knowledge from which better control measures will result Systematic investigation, testing and evaluation, designed to develop or contribute to knowledge

18 1.Understand the problem 2.Identify opportunities for prevention & control - interventions - target audience 3.Set objectives 4.Specify requirements to meet objectives 5.Design - case definitions & indicators - data needed - data sources - data transfer Steps in setting up surveillance (1)

19 5.Translate information into action - analyse - interpret - disseminate 6.Evaluate surveillance system Steps in setting up surveillance (2)

20 Disease Death Disability Recovery Source of infection Transmission Reservoir Vector Environment Direct Exposure Infection 1. Understand the problem

21 Infection Disease Death Disability Recovery Source infection Transmission Reservoir Vector Environment Direct 3. Treatment 4. Isolation/ treatment 2. Prophylaxis 6. Prevent transmission e.g. universal precautions 5. Ecological Management Exposure 1. Vaccination 2. Identify opportunities for prevention & control

22 Public Health professionals Government / Politicians Clinicians / Microbiologists / Control of Infection staff Environmental Health professionals Health service managers Health educators / teachers Public 2. Identify opportunities for prevention & control Target audiences

23 Specific Measurable Acceptable and Action oriented Realistic Time related 3. Set objectives SMART

24 3. Set objectives - examples Vague... To estimate the prevalence of hepatitis C To detect outbreaks of measles Specific, measurable, action-oriented & timed To assess the prevalence of hepatitis C in France in order to allow planning of specific health care needs for the coming 20 years To detect early time and place clustering of measles cases in order to ensure timely control of outbreaks

25 4. Requirements of the system Keep it as simple as possible!! Timeliness Sensitivity Specificity Completeness of information Representativeness Acceptability

26 5. Design – case definitions Exposed Clinical specimen Symptoms Lab confirmed Infected Seek medical attention Report

27 5. Design – examples of data needed Numerators - number of cases - number of resistant strains Denominators - population under surveillance - life births (CRS) - bacterial isolates (AMR)

28 5. Design – data sources (1) Health service –notifications –laboratories –disease registries –community services –emergency services –screening programmes (antenatal, blood donors) –pharmacy / over the counter drugs –vaccination programmes

29 5. Design – data sources (2) Veterinary –animals (domestic, wild) –food Environment –water –food –air Population statistics –deaths –denominators

30 5. Design – data sources (3) Issues cost representativeness comparability confidentiality acceptability data quality timeliness commercial sensitivity

31 5. Design – data transfer Existing infrastructure Methods –web-based –telephone Frequency Zero reporting

32 Sampling vs. comprehensive Aggregated vs. individual data Active vs. passive Statutory vs. voluntary Confidential vs. anonymous Security 5. Design – addition design issues

33 Analysis –descriptive (time, place, person) –time series –outbreak detection –molecular epidemiology –geographical information systems (GIS) Interpretation –system and data characteristics and changes –chance, bias, truth 6. Information into Action (1)

34 Dissemination of information –develop outputs in consultation with users –appropriate level of detail for action –regular review of usefulness –avoid information overload 6. Information into Action (2)

35 Did the system do what it set out to do? 7. Evaluation of surveillance system

36 Surveillance or research needed? Reliability –crude and inaccurate –incomplete –accurate denominators Sustainability –victim of success of control New threats –emerging infections –bioterrorism Timeliness Human Rights –data protection Surveillance – the challenges

37 Near patient testing Less invasive diagnostics (oral fluid, urine) New molecular typing methods Electronic patient records New data sources Behavioural surveillance Syndromic surveillance On-line, web-based systems –data entry –dissemination of information New analysis methods –GIS –bio-informatics –modelling Surveillance – the opportunities

38 Context –communicable disease control –epidemiology Definition –information for action General process –capture –analysis –dissemination Aims Criteria to set up surveillance system –public health importance –feasibility –difference between surveillance and research Different steps Challenges and opportunities Summary

39 Thank you!


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