1. is for Epi Epidemiology basics for non-epidemiologists

2. Session IV Part II Federal Public Health Surveillance

3. CDC’s Role in Surveillance Support the states –Provide training and consultation in public health surveillance –Distribute and oversee funding Receive, collate, analyze, and report data Suggest changes to be considered in public health surveillance activities Report to the World Health Organization as required and appropriate

4. TABLE II. Provisional cases of selected notifiable diseases, United States, weeks ending June 5, 2004, and May 31, 2003 (22nd week) CDC Surveillance Data Reporting

6. Federal Data Sources Over 100 federal surveillance systems Collect data on over 200 infectious and non- infectious conditions such as: –Foodborne Diseases Active Surveillance Network (FoodNet) –National West Nile Virus Surveillance System (ArboNet) –Viral Hepatitis Surveillance Program (VHSP) –Waterborne-Disease Outbreak Surveillance System –Influenza Sentinel Physicians Surveillance Network

7. Federal Surveillance Resources CDC Morbidity and Mortality Weekly Report (MMWR) http://www.cdc.gov/mmwr CDC Office of Surveillance http://www.cdc.gov/ncidod/osr/index.htm http://www.cdc.gov/ncidod/osr/index.htm

8. Council of State and Territorial Epidemiologists (CSTE) http://www.cste.org http://www.cste.org Collaborates with CDC to recommend changes in surveillance, including what should be reported / published in MMWR Develops case definitions Develops reporting procedures

9. Example: ArboNet ArboNet is a cooperative surveillance system maintained by CDC and 57 state and local health departments for detecting and reporting the occurrence of domestic arboviruses.

10. ArboNet - Data Human –Encephalitis, meningitis, fever, viremic blood donors, other Dead bird Equine Mosquito Sentinel animals (chicken, pigeon, horse) Other non-human mammals

11. What is West Nile Virus? Transmitted to humans via bites from infected mosquitoes Infection usually asymptomatic; some people have fever, headache, rash, swollen lymph glands. No infections documented in the Western Hemisphere until 1999; then 46 U.S. states reported WNV activity in 2003!

12. ArboNet – Surveillance Issues “Real-time” reporting –Novel occurrence of West Nile virus –Web-based reporting (states) –Still relies on paper-based reporting (local) Incorporates ecologic data NEDSS compatible Duplicity of human case reporting

13. Example: Influenza

14. U.S. Influenza Surveillance 1.World Health Organization (WHO) and National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories 2.State and Territorial Epidemiologists’ Reports 3.122 Cities Mortality Reporting System 4.U.S. Influenza Sentinel Providers Surveillance Network (voluntary) States may have state-specific sentinel/active or passive surveillance systems

15. U.S. Influenza Surveillance Does... Find out when and where influenza is circulating Determine what type of influenza viruses are circulating Detect changes in the influenza viruses Track influenza-related illness Measure the impact influenza is having on deaths in the United States Does Not... Ascertain how many people have become ill with influenza during the influenza season

16. Influenza-like Illness Case Definition The Influenza-Like Illness case definition for CDC’s surveillance system is: 1.Fever of 100 degrees Fahrenheit or higher AND 2. Cough OR sore throat.

17. CDC Sentinel Influenza Surveillance http://www.cdc.gov/flu/weekly/

18. Techniques for Analysis of Surveillance Data

19. Overview Considerations when working with surveillance data Access online census data Analyze surveillance data

20. Considerations Surveillance data primarily yield descriptive statistics Know the inherent strengths and weaknesses of a data set Examine data from the broadest to narrowest

21. Rely on Computers to: Generate Simple, Descriptive Statistics –Tables: frequencies, proportions, rates –Graphs: bar, line, pie –Maps: census tracts, counties, districts Aggregate or Stratify Rates –State versus county –Multiple weeks or months or years –Entire population versus age, gender, or race specific

22. Rely on Public Health Professionals to: Contact health care providers and laboratories to obtain missing data Interpret laboratory tests Make judgments about epidemiological linkages Identify or correct mistakes in data entry Determine if epidemics are in progress

23. Surveillance Data Descriptive Epidemiology

24. Person, Place, and Time Person: What are the patterns of a disease among different populations? Place: What are the patterns of a disease in different geographic locations? Time: What are the patterns of a disease when compared at different times (e.g., by month, year, decade)?

25. Tuberculosis Cases: United States 1992 - 2002 Source: http://www.cdc.gov/epo/dphsi/annsum/2002/02graphs.htm

26. Raw Numbers versus Rates

27. Ratio A ratio is any [fraction] obtained by dividing one quantity by another; the numerator and denominator are distinct quantities, and neither is a subset of the other. - Teutsch and Churchill (1994). Rates, Proportions, and Percentages are all some form of a Ratio.

28. What Do Rates Do? Measures the frequency of an event over a period of time Numerator –e.g., disease frequency for a period of time Denominator –e.g., population size

29. Why Use Rates? Rates provide frequency measures within the context of the population. Raw Surveillance Data Total Population Crude RateX 10 4 City A101,000.01100 per 10,000 City B101,000,000.00001.1 per 10,000

30. Crude versus Specific Rates Crude Rate: Rate calculated for the total population Specific Rate: Rate calculated for a sub- set of the population (e.g., race, gender, age)

31. Sample Analyses 1.Graph of Giardia cases for 2 states over time (by year)  Raw data  Rates 2.Maps of Salmonella rates by county: North Carolina, 2000  Raw Data versus Rates  Choropleth

32. Line Graph: Raw Data Giardiasis case reports, 1998–2002

33. Line Graph: Rates Giardiasis case reports, 1998–2002

34. Raw Data Rates Giardiasis, 1998-2001

35. Epi Map Instruction “Generating Maps” http://www.sph.unc.edu/nccphp/training/all_trainings/at_epi_info.htm

36. Raw Data Map North Carolina Salmonella Cases by County: 2002 Data source: NC Communicable Disease Data by county for 2000, General Communicable Disease Control Branch, Epidemiology Section, Division of Public Health

37. Choropleth Map North Carolina Salmonella Cases by County: 2002 Data source: NC Communicable Disease Data by county for 2000, General Communicable Disease Control Branch, Epidemiology Section, Division of Public Health

38. Choropleth Map North Carolina Salmonella Rates by County: 2002 Rate numerators: NC Communicable Disease Data for 2000 Rate denominators: U.S. Census population data, by county, for 2000

39. Raw Data Rates

40. Data Interpretation: Considerations Underreporting Inconsistent Case Definitions Has reporting protocol changed? Has the case definition changed? Have new providers or geographic regions entered the surveillance system? Has a new intervention (e.g., screening or vaccine) been introduced?

41. Session Summary: Surveillance Surveillance: Ongoing systematic collection, analysis, and interpretation of health data, essential to planning, implementation, and evaluation of public health practice, closely integrated with the timely dissemination to those who need to know Three broad forms of surveillance –Passive, active, and syndromic Applications: public health priorities; resource allocation; assessing programs; determining baseline rates; early detection of epidemics

42. Session Summary: Surveillance Limitations –Uneven technology, reporting burden, training and standardization needed Federal and state or local surveillance –Collaborative, reciprocal pathway for data collection and reporting Analysis and interpretation of surveillance data –Graph rates versus raw data –Investigate broad, total population rates prior to specific rates

43. References and Resources Bonetti, M. et al (August 2003). Syndromic Surveillance PowerPoint Presentation. Harvard Center for Public Health Preparedness. CDC case definitions http://www.cdc.gov/epo/dphsi/casedef/case_definitions.htm CDC infectious disease surveillance systems http://www.cdc.gov/ncidod/osr/site/surv_resources/surv_sys.htm CDC Integrated project: National electronic diseases surveillance system http://www.cdc.gov/od/hissb/act_int.htm CDC nationally notifiable infectious diseases http://www.cdc.gov/epo/dphsi/phs/infdis2004.htm http://www.cdc.gov/epo/dphsi/phs/infdis2004.htm CDC Notifiable diseases/deaths in selected cities weekly information. MMWR. June 4, 2004/53(21); 460-468 http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5321md.htm. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5321md.htm

44. References and Resources CDC Division of Public Health Surveillance and Informatics, Epidemiology Program Office: http://www.cdc.gov/epo/dphsihttp://www.cdc.gov/epo/dphsi General Communicable Disease Control Branch, Epidemiology Section, Division of Public Health, NC Department of Health and Human Services. Reportable Communicable Diseases – North Carolina. Klein, R. and Schoenborn, C. (January 2001). Age Adjustment Using the 2000 Projected U.S. Population. Healthy People 2010 Statistical Notes: No. 20. National Center for Health Statistics, Centers for Disease Control and Prevention. Last, J.M. (1988). A Dictionary of Epidemiology, Second Edition. New York: Oxford University Press. Teutsch, S. and Churchill, R. (1994). Principles and Practice of Public Health Surveillance. New York: Oxford University Press. U.S. Department of the Interior, U.S. Geological Survey (January 19, 2005). http://westnilemaps.usgs.gov/background.html http://westnilemaps.usgs.gov/background.html