1. This presentation is made available through a Creative Commons Attribution-Noncommercial license. Details of the license and permitted uses are available at http://creativecommons.org/licenses/by-nc/3.0/ © 2010 Dr. James C. Scott and the Clinic on the Meaningful Modeling of Epidemiological Data http://creativecommons.org/licenses/by-nc/3.0/ Title: Public Health, Epidemiology, and Models Attribution: Dr. Jim Scott, Clinic on the Meaningful Modeling of Epidemiological Data Source URL: http://lalashan.mcmaster.ca/theobio/mmed/index.php/Public_Health%2C_Epidemiology%2C_and_Model s http://lalashan.mcmaster.ca/theobio/mmed/index.php/Public_Health%2C_Epidemiology%2C_and_Model s For further information please contact Dr. Jim Scott (jimscott73@gmail.com).

2. MMED African Institute for the Mathematical Sciences Muizenberg, South Africa May, 2010 Jim Scott, Ph.D, M.A., M.P.H.

3.  Published analysis of London mortality data in 1662  Recognized patterns and trends such as male-female disparities and high infant mortality 3

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6. In 1632 Plague: 8 Buried: 9535 6

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9.  “The science of preventing disease, prolonging life, and promoting physical health and efficiency through organized community efforts… ” - Winslow  Prevention is job #1  Works at the population level 9

10. “I believe the history of public health might be written as a record of successive redefinings of the unacceptable.” - George Vicker 10

11. 11 A Summarized History of International Public Health (Merson, Black, Mills, 2 nd ed.)

12. 12 Public Health Improvements Cleaner Water Vaccinations Family Planning Cleaner Food Smallpox Eradication Education Improved Sanitation Improved Hygiene Cleaner Air Tobacco Control Better Nutrition Vector Control Google: Life expectancyLife expectancy

13.  Key concepts  Prevention is job #1  Interdisciplinary  Everyone has a right to health  Linked to government  Works at the population level  Different than medicine 13

14.  Assess health of populations (surveillance)  Policy development  Assure that services are available  Prevent disease  Assess health of individuals (diagnosis)  Develop treatment plan (regimen)  Administer treatment  Cure the patient Public HealthMedicine 14

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16.  Assessment :  Epidemiology and Statistics 16

17.  Policy Development  Government and International Organizations ▪ e.g. The World Health Organzation 17

18.  Assurance  Implementation and maintenance  Governments and Public Health Infrastructure 18

19.  Five Steps  Define the problem  Determine risk factors  Develop interventions  Implementation  Assessment 19

20.  The problem:  1966: 10 – 15 million cases of smallpox in 50+ countries  1-2 million deaths annually  ~ 30% case-fatality ratio  Higher in children  Survivors scarred for life 20 Source: Millions Saved: Proven Successes in Global Health, Center for Global Development, 2004

21.  Natural History/Risk Factors  Variola virus  Airborne / contact with an infected person  Non-infectious for up to 17 days  Flu-like symptoms – high fever  Rash 21

22.  Intervention: vaccination  In existence since 18 th century – Edward Jenner  Improved vaccine in 1920s  1959: Global eradication program endorsed by the WHO 22

23.  Implementation  1959: 1 fulltime WHO medical officer, 1 assistant  National vaccination campaigns  1965: World Health Assembly – “eradication of smallpox is a main objective of the WHO”  1967: Smallpox Eradication Program  1970’s: focused ‘containment’ teams  1973: 5 countries remaining  1977: last endemic case 23

24. 24 Source: Vaccines, 3 rd ed.,W.B. Saunders Co. 1999 The Decline of Smallpox

25.  Assessment  2 years of surveillance and searching  May 1980: Smallpox declared “eradicated” 25

26.  Barriers to public health  Economic  Moral/religious  Individual freedom  Political 26

27.  Public Health  Prevention  Populations  Challenging 27

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29. 29 Policy Development Assessment Assurance Epidemiology

30.  “The study of the  distribution and  determinants  of health-related states or events  in specified populations, and the application of this study to control health problems” - J. Last, Dictionary of Epidemiology 30

31.  The…  Who  What  When  Where  Why  and How ……of Disease Descriptive Epidemiology Analytic Epidemiology 31

32. Slide courtesy of Warren Winkelstein 32

33.  Describe Disease in the Population  Surveillance, observation, research, experiments  Person, place, and time  Determinants  Physical, biological, social and behavioral factors that influence health  Natural History of Disease  Symptoms, pathogenisis, incubation  Design/Implement interventions  Control disease  Inform Policy  Use findings to promote, protect, and restore health – “Big Picture” 33

34.  Describe Disease in the Population - Surveillance - Distribution of disease  Determinants of Disease - Outbreak investigations - Observational studies - Experimental studies (RCTs)  Interventions - Mathematical modeling 34

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40. Centers for Disease Control and Prevention 40

41. Susceptible Host Subclinical Disease (Incubation period) Clinical Disease Recovery, Disability or Death Time Exposure Pathological ChangesUsual Time of Diagnosis Onset of Symptoms

42.  Agent – Hepatitis A virus  Reservoir – Humans, and rarely captive chimpanzees  Mode of Transmission – Person-to-person by fecal- oral route  Incubation period – 15 to 50 days, depending on dose  Period of communicability – Greatest during latter half of incubation period, continues for a few days after onset of jaundice  Symptoms – Fever, nausea, abdominal discomfort, jaundice

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44. 44 0.85 vs 2.11, a reduction in HIV incidence of approximately 60%

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46. 46 Universal voluntary HIV testing with immediate antiretroviral therapy as a strategy for elimination of HIV transmission: a mathematical model Reuben M Granich, Charles F Gilks, Christopher Dye, Kevin M De Cock, Brian G Williams Lancet 2009; 373

47.  Population or community health assessment  Surveillance  Individual decision making  Should I smoke?  Completing the clinical picture  Natural History of Disease  Search for causes  HPV and Cervical Cancer  Public health action  Circumcision 47

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49.  Models allow us to gain insight into public health questions (e.g. Universal testing)  Differences between: ▪ What factors increase the risk of HIV transmission? (Analytic Epidemiology) ▪ In what populations is HIV incidence/prevalence the highest? (Descriptive Epidemiology) ▪ By how much could we expect the incidence of HIV to decrease in South Africa if 80% of all sexually active people used condoms 80% of the time? (Public Health Impact) 49

50.  1) Simple as possible  Avoid unnecessary complexity  Only add complexity when the research question demands it  2) Based on what is known  Biological systems  DATA 50 Implies we must know relevant: - biology - statistics (how to make sense of data)

51. Slide courtesy of Warren Winkelstein 51