1. Field epidemiology Behrooz Behbod Specialty Registrar in Public Health 4 th February 2016

2. Learning objectives Describe the purpose of field epidemiology Understand the key concepts of disease surveillance Understand the role of field epidemiology in outbreak investigations

3. What is Epidemiology? A tool for public health What’s your experience of epidemiology? Development of the evidence base "the study of what is upon the people" Study of the distribution and determinants of health-related states - WHO

4. What is Field Epidemiology? “the practice of epidemiology in real time and real place, which in turn involves both science and art, and applies when the problem is unexpected. A timely response may be demanded: public health epidemiologists must travel to and work in the field to solve the problem, and the extent of the investigation is likely to be limited because of the imperative for timely intervention”. Am. J. Epidemiol. (2002) 156 (8): 783-784. doi: 10.1093/aje/kwf103

5. What's different about field epi? Time pressure to take public health action Limits to resources and methods (usually observational – cohort / case control) Data quality can vary Not all facts established before hypothesis generation Different types of evidence used together with epidemiology (e.g., microbiology, environmental exposure assessment) Good communication skills are essential

6. PHE Field Epidemiology Service -Work closely wih CCDCs -Regional epidemiologists -Scientists -Information officers/ managers -Admin team -Trainees 2013 2015

7. Overview of role Both ACUTE and STRATEGIC -Intelligence -Surveillance -Field investigations and response -Rapid research and development -Epidemiology training

8. The very model of a modern epidemiologist…

9. 1848-53 – South London Ecological study to generate a hypothesis compared cholera mortality among sizeable populations who were exposed to water of varying degrees of sewage contamination supplied by different water companies

10. The very model of a modern epidemiologist… Broad Street outbreak of 1854 Specific outbreak investigations, which served to make his hypothesis on the faecal oral route of cholera transmission plausible. He examined water and reconstructed how the water supply could have become infected.

11. Taking action http://sphweb.bumc.bu.edu/otlt/MPH-Modules/EP/EP713_History/EpidemicCurve.jpg Is this an epidemic curve? What does it show?

12. Taking action http://sphweb.bumc.bu.edu/otlt/MPH-Modules/EP/EP713_History/EpidemicCurve.jpg What could have helped John Snow take public health action sooner?

13. Getting ahead of the curve Early warning system; early recognition of when we have more cases than expected

14. Surveillance The processes of data collection, analysis, interpretation and dissemination that are: undertaken on an ongoing basis provide measures of population or group health status or determinants of health (hazards, exposures, behaviours) provide comparison against historical or geographical baselines/comparators or defined levels/triggers for action for which there is an agreed and explicit set of actions, timeframes and accountabilities for taking those actions, that will be initiated or informed by the outputs. Information for action

15. Types of surveillance Active surveillance special effort to collect data and confirm diagnoses to ensure more complete reports, such as surveys and outbreak investigations encompasses formal and informal communications (such as phone calls to seek information) Passive surveillance use of routine sources of information such as notifications, laboratory reports, Health Episode Statistics (HES)Health Episode Statistics

16. Types of surveillance Sentinel surveillance geographic: reporting sources shown at specific sites high risk groups: drug users etc Real time/syndromic surveillance On going Set of symptoms or syndromes is monitored rather than a specific diagnosis PHE’s real-time syndromic surveillance team (ReSST)

17. Identifying issues What is normal? What is higher than expected? could it be due to chance could it be due to errors or bias could it be due to changes in population What do we compare to? previous period/season other areas/locations a set threshold for action a statistical threshold

18. Outbreak detection - exceedances

19. STIs Comparison is between infections and to previous years?

20. STIs Has this taken account of chance?

21. Describing surveillance data by place is also important

22. What does the map show? Where is the problem worst? Where do resources need to be focused?

23. Has the message changed with this map? Could chance be playing a role? Would a map show significant differences in rates be better?

24. Outbreaks and incidents

25. What is an outbreak Cluster Outbreak Epidemic Pandemic

26. What is an outbreak Cluster Outbreak Epidemic Pandemic What is an incident Chemical contamination – air/water Poisons Environmental events - flooding

27. Outbreak investigations What are the steps?

28. Outbreak investigations 1.Determine the existence of an outbreak 2.Confirm the diagnosis 3.Define a case 4.Search for cases 5.Generate hypotheses using descriptive findings 6.Test hypotheses with an analytical study 7.Draw conclusions 8.Compare hypothesis with established facts, additional studies 9.Communicate findings 10.Execute prevention measures

29. Outbreak investigations 1.Determine the existence of an outbreak 2.Confirm the diagnosis 3.Define a case 4.Search for cases 5.Generate hypotheses using descriptive findings 6.Test hypotheses with an analytical study 7.Draw conclusions 8.Compare hypothesis with established facts, additional studies 9.Communicate findings 10.Execute prevention measures where epidemiology is particularly important?

30. Outbreak investigations 1.Determine the existence of an outbreak 2.Confirm the diagnosis 3.Define a case 4.Search for cases 5.Generate hypotheses using descriptive findings 6.Test hypotheses with an analytical study 7.Draw conclusions 8.Compare hypothesis with established facts, additional studies 9.Communicate findings 10.Execute prevention measures where epidemiology is particularly important?

31. Determine the existence of an outbreak Determine whether there is a clustering of cases Review incidence in the past in the area of the outbreak. Check for recent changes in the surveillance system (numerator). Check for recent changes in the population size (denominator).

32. Descriptive epidemiology – person Describe the people Do they all have the same symptoms? Do they have similar demographics? Do they have common exposures? What proportion of cases have each exposure

33. Descriptive epidemiology Describe the place Did cases all attend an event? Do cases live/work/spend time near each other? Has infection spread between areas over time?

34. Ebola August 2014

35. Descriptive epidemiology – time Describe what happened over time How many cases occurred within a set time? Can we define an incubation period? Can we define a likely source type? Epidemic curves are used to summarise the onset of cases over time. Shape of the curve can help show what kind of source we might be dealing with.

36. What does this tell you?

37. Point Source Outbreaks

38. What does this tell you?

39. Continuing Common Source Outbreaks

40. What does this tell you?

41. Propogated Outbreaks (person-to-person transmission)

42. Hypothesis formulation Synthesise information About cases links in time and place microbiological information (clinical or environmental samples) incubation period outliers

43. Analytical epidemiology Test your hypothesis Allows you to present epidemiological evidence of association between exposure and becoming a case Key difference from descriptive epidemiology is that information about non-cases or those not exposed are used as a comparison Two main study types Retrospective cohort study Case control study

44. Summary Field epidemiology is a subspecialty of epidemiology Infectious disease surveillance is an important tool for monitoring population heath and identifying outbreaks Outbreaks require robust investigations to be carried out quickly Descriptive epidemiology (person, place, time) Analytical epidemiology is used to test your hypothesis We are interested in generating information for action

45. EIS A 2-year postgraduate fellowship of service and on-the-job training for health professionals interested in the practice of epidemiology www.cdc.gov/eis CDC Headquarters – Atlanta, GA National Center for Health Statistics – Hyattsville, MD National Institute for Occupational Safety and Health – Morgantown, WV US State (e.g., California) or city (e.g., New York City) position Similar programmes: Field Epidemiology Training Programme Public Health England www.hpa.org.uk/EventsProfessionalTraining/FieldEpidemiologyTrainingProgramme/ European Programme for Intervention Epidemiology Training (EPIET) European Centre for Disease Prevention & Control (ECDC) www.ecdc.europa.eu/en/epiet/ ‎www.ecdc.europa.eu/en/epiet/

46. September 11, 2001

47. Hurricane Katrina

48. BP Gulf Coast Oil Spill – Deepwater Horizon  Buttke D, et al. Community assessment for public health emergency response (CASPER) one year following the Gulf Coast oil spill: Alabama and Mississippi, 2011. Prehosp Disaster Med. 2012;27(6):496-502. From www.telegraph.co.uk

51. Acknowledgements Public Health England Field Epidemiology Service East Midlands Selected slides adapted from European Programme for Intervention Epidemiology Training (EPIET) Training materials Selected slides adapted from SARS Outbreak Study 2 http://epiville.ccnmtl.columbia.edu/