1. Surveillance, Epidemiology, and Tracing Epidemiology Part 1: Principles of Epidemiology Adapted from the FAD PReP/NAHEMS Guidelines: Surveillance, Epidemiology, and Tracing (2014).

2. Introduction to epidemiology Overview of disease characteristics Disease occurrence Understanding data and measures of disease USDA APHIS and CFSPHFAD PReP/NAHEMS Guidelines: Surveillance, Epi, and Tracing - Epidemiology Part 1 This Presentation

3. Study of disease in populations and factors that determine the occurrence of disease USDA APHIS and CFSPHFAD PReP/NAHEMS Guidelines: Surveillance, Epi, and Tracing - Epidemiology Part 1 What is Epidemiology?

4. Functions of Epidemiology USDA APHIS and CFSPHFAD PReP/NAHEMS Guidelines: Surveillance, Epi, and Tracing - Epidemiology Part 1

5. Surveillance – Ongoing data collection, analysis, interpretation, and dissemination – Used to determine specific actions for FAD mitigation Field investigation – Used to collect additional information about cases identified via surveillance Disease source, history of disease, etc. USDA APHIS and CFSPHFAD PReP/NAHEMS Guidelines: Surveillance, Epi, and Tracing - Epidemiology Part 1 Core Functions

6. Analytic studies – Utilizes information gleaned from surveillance activities and field investigations – Disease rates and risk factors Evaluation – Effectiveness – Efficacy – Impact of activities USDA APHIS and CFSPHFAD PReP/NAHEMS Guidelines: Surveillance, Epi, and Tracing - Epidemiology Part 1 Core Functions (cont’d)

7. Disease Characteristics USDA APHIS and CFSPHFAD PReP/NAHEMS Guidelines: Surveillance, Epi, and Tracing - Epidemiology Part 1

8. Course of disease progression – Pathogen exposure – Subclinical illness – Onset of clinical signs – Recovery, disability, or death USDA APHIS and CFSPHFAD PReP/NAHEMS Guidelines: Surveillance, Epi, and Tracing - Epidemiology Part 1 Natural History of Disease

9. Many ways to transmit disease – Direct transmission – Indirect transmission Zoonotic diseases – Diseases transmissible between animals and humans – May be transmitted directly or indirectly USDA APHIS and CFSPHFAD PReP/NAHEMS Guidelines: Surveillance, Epi, and Tracing - Epidemiology Part 1 Transmission Modes

10. Disease Occurrence USDA APHIS and CFSPHFAD PReP/NAHEMS Guidelines: Surveillance, Epi, and Tracing - Epidemiology Part 1

11. Endemic – Disease present in population or geographical area at all times Outbreak – Occurrence of more cases of disease than expected Given area/group, specific time period – May be used interchangeably with the term “epidemic” USDA APHIS and CFSPHFAD PReP/NAHEMS Guidelines: Surveillance, Epi, and Tracing - Epidemiology Part 1 Levels of Disease

12. Pandemic – An outbreak/epidemic that has spread over several countries USDA APHIS and CFSPHFAD PReP/NAHEMS Guidelines: Surveillance, Epi, and Tracing - Epidemiology Part 1 Levels of Disease (cont’d)

13. Environment – Husbandry, housing, climate/season, presence of vectors Agent – Host range, environmental resistance, tissue affinity, dose, mode of transmission Host – Species, breed, age, nutritional and immune status USDA APHIS and CFSPHFAD PReP/NAHEMS Guidelines: Surveillance, Epi, and Tracing - Epidemiology Part 1 Causation

14. A characteristic that is associated with an increase in the occurrence of a particular disease May include: – Age – Species – Location – Contact USDA APHIS and CFSPHFAD PReP/NAHEMS Guidelines: Surveillance, Epi, and Tracing - Epidemiology Part 1 Risk Factors

15. Understanding Data and Measures of Disease USDA APHIS and CFSPHFAD PReP/NAHEMS Guidelines: Surveillance, Epi, and Tracing - Epidemiology Part 1

16. Measures of central tendency – Mean, median, and mode Range – Difference between largest and smallest value Standard deviation – Spread around mean value of data set USDA APHIS and CFSPHFAD PReP/NAHEMS Guidelines: Surveillance, Epi, and Tracing - Epidemiology Part 1 Descriptive Statistics

17. Represents range within which the true value lies Calculated based on a percentage – 95% commonly used 95% confidence interval – True value falls within the given range 95 percent of the time USDA APHIS and CFSPHFAD PReP/NAHEMS Guidelines: Surveillance, Epi, and Tracing - Epidemiology Part 1 Confidence Interval

18. Prevalence – Total number of cases of a disease in a given population at a specific time Incidence – Number of new cases of disease in a defined population over a specific time period USDA APHIS and CFSPHFAD PReP/NAHEMS Guidelines: Surveillance, Epi, and Tracing - Epidemiology Part 1 Measures of Disease

19. Mortality rate – Number of deaths in a defined population during a specific time period Case fatality rate – Percentage of animals diagnosed with a specific disease who die as a result of the disease within a specified period of time USDA APHIS and CFSPHFAD PReP/NAHEMS Guidelines: Surveillance, Epi, and Tracing - Epidemiology Part 1 Measures of Disease (cont’d)

20. Examines the differences in occurrence of disease in different segments of the population – Factors that might influence disease occurrence – Risk ratio and odds ratio USDA APHIS and CFSPHFAD PReP/NAHEMS Guidelines: Surveillance, Epi, and Tracing - Epidemiology Part 1 Measures of Association

21. Tables, graphs, and charts – Visual means for comparing data – Demonstrate patterns, differences, and other relationships USDA APHIS and CFSPHFAD PReP/NAHEMS Guidelines: Surveillance, Epi, and Tracing - Epidemiology Part 1 Displaying Data

22. Maps and GIS – Geographic location of disease – Levels and rates of disease USDA APHIS and CFSPHFAD PReP/NAHEMS Guidelines: Surveillance, Epi, and Tracing - Epidemiology Part 1 Displaying Data (cont’d)

23. FAD PReP/NAHEMS Guidelines: Surveillance, Epidemiology, and Tracing, and SOP: Surveillance – http://www.aphis.usda.gov/fadprep http://www.aphis.usda.gov/fadprep Surveillance, Epidemiology, and Tracing web-based training module – http://naherc.sws.iastate.edu/ http://naherc.sws.iastate.edu/ USDA APHIS and CFSPH FAD PReP/NAHEMS Guidelines: Surveillance, Epi, and Tracing - Epidemiology Part 1 For More Information

24. Authors (CFSPH) Kerry Leedom Larson, DVM, MPH, PhD, DACVPM Glenda Dvorak, DVM, MPH, DACVPM Janice Mogan, DVM Courtney Blake, BA Reviewers (USDA APHIS VS) Dr. R. Alex Thompson Dr. Lowell Anderson Dr. Steve Goff Dr. Fred Bourgeois USDA APHIS and CFSPH FAD PReP/NAHEMS Guidelines: Surveillance, Epi, and Tracing - Epidemiology Part 1 Guidelines Content

25. Acknowledgments Development of this presentation was by the Center for Food Security and Public Health at Iowa State University through funding from the USDA APHIS Veterinary Services PPT Authors: Patricia Futoma, Veterinary Student; Kerry Leedom Larson, DVM, MPH, PhD, DACVPM Reviewers: Janice Mogan, DVM; Melissa Lang, BS