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Introduction to Public Health Surveillance Dr Giri Shankar Lazareto de Mahon, Menorca, Spain 24 September –12 October 2012 &

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Presentation on theme: "Introduction to Public Health Surveillance Dr Giri Shankar Lazareto de Mahon, Menorca, Spain 24 September –12 October 2012 &"— Presentation transcript:

1 Introduction to Public Health Surveillance Dr Giri Shankar Lazareto de Mahon, Menorca, Spain 24 September –12 October 2012 &

2 & 2 Surveillance Track 6 Lectures; 2 case studies Mon 24 Sept – Introduction to PH surveillance Tue 25 Sept – Event based surveillance Wed 26 Sept Key elements of a surveillance system ( I & II) Analysis of surveillance data Fri 28 Sept – Evaluation of surveillance system

3 & 3 Outline of Lecture Definition of Surveillance Surveillance Loop Uses of Surveillance with examples Summary

4 & What is Surveillance? 4 The systematic process of collection, transmission, analysis and feedback of public health data for decision making Could you drive without looking at the traffic? Can you make public health decisions in the absence of data?

5 & 5 The continued watchfulness over the distribution and trends in the incidence of disease through the systematic collection, consolidation and evaluation of morbidity and mortality reports and other relevant data Alexander Langmuir, Chief Epidemiologist, CDC Continuous analysis, interpretation and feedback of systematically collected data, generally using methods distinguished by their practicality, uniformity and rapidity, rather than by accuracy and completeness WJ Eylenbosch & ND Noah (eds). Surveillance in Health and Disease. Oxford University Press The systematic ongoing collection, collation and analysis of data for public health purposes and the timely dissemination of public health information for assessment and public health response as necessary. World Health Assembly 2005 Definitions of surveillance

6 & 6 Surveillance is Information for action

7 & 7 The surveillance loop Health care system Surveillance centre Reporting Feedback, recommendations Analysis, interpretation Event Action Data Information Planning, Evaluation, Policy formulation Source: S Hahne, S Cotter, D Werker - EPIET

8 8 Event and population under surveillance Population and time Everyone in the country or region Patients in hospitals Employees in a factory All children in the winter months Event Disease Syndrome Acute flaccid paralysis Influenza-like illness Diarrhoea Infection Public health issue Antimicrobial resistance Environment Vector population Water quality &

9 & 9 The surveillance loop Health care system Surveillance centre Reporting Feedback, recommendations Analysis, interpretation Event Action Data Information Planning, Evaluation, Policy formulation Source: S Hahne, S Cotter, D Werker - EPIET

10 & 10 Surveillance methods- key data items collected Numerators ­ number of cases of disease ­ antibody positive samples ­ number of resistant strains Descriptors ­ characteristics of patients, strains etc Denominators ­ total population at risk (or sub-sample) in a given time frame ­ total number of strains examined

11 11 Case definition & YES A case is an event An event is something that happens to: A person, In a given place, At a given time A case definition is a set of criteria that triggers reporting NO A case is not a person Events do not exist if you lack info: On the person On the place On the onset date A case definition is not a diagnosis made to decide treatment

12 12 Case definition Includes: Time, place, person Clinical features and /or Laboratory results and/or Epidemiological features Should be: Clear, simple Field tested Stable and valid &

13 Possible case Clinical diagnosis of meningitis or septicaemia or other invasive disease where the CCDC/CPH, in consultation with the clinician and microbiologist, considers that diagnoses other than meningococcal disease are at least as likely Probable case Clinical diagnosis of meningitis or septicaemia or other invasive disease where the CCDC/CPH, in consultation with the physician and microbiologist, considers that meningococcal infection is the most likely diagnosis Confirmed case Clinical diagnosis of meningitis, septicaemia or other invasive disease AND at least one of: Neisseria meningitidis isolated from normally sterile site Gram negative diplococci in normally sterile site Meningococcal DNA in normally sterile site Meningococcal antigen in blood, CSF or urine. 13 & Case definition

14 14 Reporting (data transfer) Data transfer method Paper by mail Telephone Secure Internet Data transfer frequency For every case Daily Weekly Quartery Individual data Identified – name, personal id number Non-identified – but possible to trace back Anonymous – impossible to trace back Aggregated data Numbers Tabulated numbers – by sex, age group etc &

15 & 15 The surveillance loop Health care system Surveillance centre Reporting Feedback, recommendations Analysis, interpretation Event Action Data Information Planning, Evaluation, Policy formulation Source: S Hahne, S Cotter, D Werker - EPIET

16 & 16 Surveillance data sources Generic sources ­ Notifications of infectious diseases ­ Microbiology laboratory reports ­ Hospital Episode Statistics ­ Primary Care spotter practices ­ Screening programmes (antenatal, blood donors) ­ Prescriptions / over the counter drug sales

17 & 17 Surveillance data sources Disease or patient specific sources ­ Customised surveillance programmes voluntary e.g. HIV/AIDS surveillance mandatory e.g. Clostridium difficile enhanced e.g. meningococcal disease ­ Patient registers e.g. renal registry ­ Clinical networks e.g. British Paediatric Surveillance Unit (BPSU) Non health sources ­ Veterinary medicine domestic & wild animals, animal husbandry ­ Environment health water, food, air sampling ­ Population statistics e.g. death registrations

18 & 18 The surveillance loop Health care system Surveillance centre Reporting Feedback, recommendations Analysis, interpretation Event Action Data Information Planning, Evaluation, Policy formulation Source: S Hahne, S Cotter, D Werker - EPIET

19 & 19 Analysis of surveillance data Descriptive use Measure of disease frequency ­ incidence (no. cases/population at risk over given time period) e.g. 5 cases per 1000 person years; 0.3 cases per 1000 bed-days ­ prevalence (no. cases/population at risk at a set time) e.g. 15% of patients sampled antibody positive; 3% strains erythromycin resistant Data described according to time-person-place Analytical use Comparison between groups to gain a measure of increased risk e.g. case fatality in males vs females e.g. change in rate of infection over time

20 & 20 Surveillance is Information for action

21 21 Purposes and uses of surveillance describe the disease and its importance monitor secular trends detection of outbreaks & emerging epidemics monitor health practices monitor changes in infectious agents provide an evidence base for policy and guidance formulation monitor control and prevention measures generate hypotheses and stimulate public health research what is the problem? how do we deal with it? did it work? how can we do better? &

22 & 22 Purposes and uses of surveillance describe the disease and its importance monitor secular trends detection of outbreaks & emerging epidemics monitor health practices monitor changes in infectious agents provide an evidence base for policy and guidance formulation monitor control and prevention measures generate hypotheses and stimulate public health research

23 & 23 Notifications of Meningococcal Infections Cases of group B and C meningococcal disease in England and Wales, by age group No of cases Year

24 & 24 Purposes and uses of surveillance describe the disease and its importance monitor secular trends detection of outbreaks & emerging epidemics monitor health practices monitor changes in infectious agents provide an evidence base for policy and guidance formulation monitor control and prevention measures generate hypotheses and stimulat public health research

25 25 TB notification and death rate England and Wales, & Year

26 & 26 Purposes and uses of surveillance describe the disease and its importance monitor secular trends detection of outbreaks & emerging epidemics monitor health practices monitor changes in infectious agents provide an evidence base for policy and guidance formulation monitor control and prevention measures generate hypotheses and stimulate public health research

27 27 UK epidemiology: containment phase RCGP weekly ILI rate 2009/10 and recent years. * Baseline activity 200 per 100,000

28 28 Age and sex distribution of confirmed H1N1v cases in the UK, 30 June 2009 (n= 6766)(FluZone) & Age Group (yrs) No of cases

29 29 Regional Spread of cases - May 10 May31 May &

30 30 Regional spread of cases - June 05 June 12 June 19 June 26 June &

31 31 UK epidemiology: treatment phase RCGP weekly ILI rate 2009/10 and recent years, England * Baseline activity 200 per 100,000 &

32 32 UK epidemiology: launch of National Pandemic Flu Service RCGP weekly ILI rate 2008/09 and recent years, England * Baseline activity 200 per 100,000 &

33 33 UK epidemiology: end of first wave RCGP weekly ILI rate 2009/10 and recent years. * Baseline activity 200 per 100,000 &

34 34 UK epidemiology: end of first wave RCGP weekly ILI rate 2009/10 and recent years. * Baseline activity 200 per 100,000 &&

35 & 35 Purposes and uses of surveillance describe the disease and its importance monitor secular trends detection of outbreaks & emerging epidemics monitor health practices monitor changes in infectious agents provide an evidence base for policy and guidance formulation monitor control and prevention measures generate hypotheses and stimulate public health research

36 & 36 Distribution of surgical site infection by category of surgical procedure Oct Dec 2003

37 & 37 Purposes and uses of surveillance describe the disease and its importance monitor secular trends detection of outbreaks & emerging epidemics monitor health practices monitor changes in infectious agents provide an evidence base for policy and guidance formulation monitor control and prevention measures generate hypotheses and stimulate public health research

38 38 Staphylococcus aureus bacteraemia reports and methicillin susceptibility England & Wales &

39 & 39 Purposes and uses of surveillance describe the disease and its importance monitor secular trends detection of outbreaks & emerging epidemics monitor health practices monitor changes in infectious agents provide an evidence base for policy and guidance formulation monitor control and prevention measures generate hypotheses and stimulate public health research

40 & 40

41 & 41 Purposes and uses of surveillance describe the disease and its importance monitor secular trends detection of outbreaks & emerging epidemics monitor health practices monitor changes in infectious agents provide an evidence base for policy and guidance formulation monitor control and prevention measures generate hypotheses and stimulate public health research

42 42 Laboratory confirmed serogroup C meningococcal disease end of catch- up start of routine immunisation and catch up (15-17y, <1y) Source: Meningococcal Reference Unit/CfI &

43 & 43 Cumulative reports of Pneumococcal Disease due to the seven serotypes IN Prevenar : Children < 2 Years in E&W by Epidemiological Year

44 & 44 Cumulative reports of Pneumococcal Disease due to the seven serotypes NOT in Prevenar : Children < 2 Years in E&W by Epidemiological Year

45 & 45 Purposes and uses of surveillance describe the disease and its importance monitor secular trends detection of outbreaks & emerging epidemics monitor health practices monitor changes in infectious agents provide an evidence base for policy and guidance formulation monitor control and prevention measures generate hypotheses and stimulate public health research

46 & 46 MRSA bacteraemia in children proposal to undertake enhanced surveillance of MRSA in children

47 & 47 Summary Surveillance is a lively line of communication that works both ways A surveillance system counts the same events, consistently, every day Surveillance directs decision-making

48 & 48 Surveillance is Information for action Remember


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