Population Health for Health Professionals

1. Population HealthforHealth Professionals

2. EMERGING INFECTIOUS DISEASES PART 1

3. Purpose • The purpose of this module is to provide an exposure to some of the emerging diseases that will affect the health of the public and to examine the challenges and opportunities they pose to the public health system

4. At the completion of this module you will be able to • Describe the causes and contributing factors which lead to the emergence of infectious diseases. • Describe the latest emerging infections which have the potential to threaten people living in the United States. • Describe some of the measures that can be used to control and contain these diseases

5. What Are EmergingInfectious Diseases? These are human illnesses caused by microorganisms or their poisonous byproducts and having the potential for occurring in epidemic numbers.

6. Why are we concerned about Emerging Infectious Diseases? • These diseases: • Pose a threat to all persons regardless of age, sex, lifestyle, ethnic background, or socioeconomic status • Cause suffering and death • Impose a financial burden on society

8. Over the past century, infectious diseases have decreased as a cause of death in this country • Improved sanitation, vaccination and antibiotics have played a large part in this decrease and are responsible to the increase in the lifespan of our residents • However, in the past twenty years the incidence of emerging infectious diseases has increased

9. FACTORS RELATED TO THE EMERGENCE OF INFECTIOUS DISEASES Factors studiedExamples 1. Biological----------Genes, microbes, medicines, vaccines, blood and organ transplants, rapid microbial adaptation and resistance to antibiotics 2. Behavior----------Sports, nutrition, sexuality, tobacco, alcohol, international travel 3. Environment: physical--------Air, water, toxins, radiation, pollution, noise, agricultural development, climate change, technology 4. Environment: social ---------Housing, education, employment, and working conditions 5. Environment: human rights-------Discrimination, war, torture, physical and mental abuse, lack of access to health care, prevention and health education 6. Breakdown of traditional basic public health infrastructure

10. An existing organism given the selective advantage by such things as a changing environmental condition and given the opportunity can infect a new host population • An organism can re-emerge in a drug resistant form

11. In the US, about 25% of physician visits are attributed to infectious diseases • In 1993, direct and indirect costs were estimated to be more than $120 billion. Today, these costs are substantially more

12. Economic and Societal Impact of Some Infectious Diseases Economic and Social Impact of Some Infectious Diseases

13. How Are Infectious Diseases Acquired? • Inhalation • Ingestion • Food, water, soil • Percutaneous inoculation • Absorption from mucous membranes • Exposure to blood and body fluids

14. CDC’s Target Areas • Antimicrobial resistance • Foodborne and waterborne diseases • Vectorborne and zoonotic diseases • Diseases transmitted through blood transfusions or blood products • Chronic diseases caused by infectious agents

15. CDC’s Target Areas (cont.) • Vaccine development and use • Diseases of persons with impaired host defenses • Diseases of pregnant women and newborns • Diseases of travelers, immigrants, and refugees

16. CONTROL MEASURES • Water treatment • Vector control • Rodent reduction • Vaccination • Antibiotics

17. ROLE OF PUBLIC HEALTH Surveillance and early response (detect, investigate, initiate action and monitor) • Assessment of health status, risks, and services available to a community • Development of health policy • Assurance of quality services (discourage inappropriate use of antibiotics) • Laboratory identification

18. ROLE OF PUBLIC HEALTH (CONT.) • Rapid communication with medical providers and hospitals • Communication with the media • Public and health care provider education (role in transmission, modification of lifestyle to avoid disease, etc.) • Environmental assessment and remediation, e.g. food inspection, water supply inspection, vector control)

19. EMERGING INFECTIOUS DISEASES PART 2

20. New EmergingInfectious Diseases The following diseases have recently emerged as public health concerns and will be discussed more fully in the slides that follow: • Atypical Influenza • Severe Acute Respiratory Syndrome (SARS) • West Nile encephalitis (WNV) • Monkey Pox • Ebola • Hantavirus

21. INFLUENZA and ATYPICAL INFLUENZA

23. Influenza: USA annual stats • 10-20 % of population contract influenza annually • 36,000 die (excess mortality), more than 90% are 65 and older • 226,000 hospitalizations (2004 data) • 38 million missed school days, 70 million missed work days • $ 1-3 Billion in direct costs R. Ball, MD, MPH

24. Worldwide 3 to 5 million people are infected with influenza each year with 250,000 to 500,000 deaths

25. Major Influenza Pandemics of the Twentieth Century Excess US Mortality Major Years Subtype ’17-’18 H1N1 550,000 ’57-’58 H2N2 70,000 ’68-69 H3N2 36,000 NEXT ? H5N1 (Avian) ?

26. Influenza Surface Proteins Neuraminidase (N) Hemagglutinin (H) RNA (highly mutagenic) M2 protein (only on type A)

27. The Usual Human Influenza A Strains within the Last Century Major influenza surface antigens: Hemagglutinin Neuraminidase Asian Flu Hong Kong Flu 1920 1957 1968 1977 2003 Thanks to Eric Brenner, MD for slide.

28. The Wider Family of Influenza Critters 15H x 9N 135 potential HN combinations *H5N1 already spreading in SE Asia (mortality 1 in 2); inefficient person-person transmission; USA is developing a limited vaccination program vs. A/ H5N1 “Avian Flu” *H5N1 * Slide by Eric Brenner, MD & R. Ball, MD, MPH

29. Emergence of New Influenza A Virus Subtypes in Humans Thanks to JJ Gibson, MD for graph.

30. Is this virus actively reassorting its genes to achieve a unique combination of virulence and communicability? Thanks to Eric Brenner, MD for slide.

31. Avian influenza A (H5N1) that infects poultry is a concern due to the potential for spread of an influenza A variant to humans, and the eventuality of human to human transmission, and a pandemic of atypical influenza. • Recent reports from several Asian countries that are experiencing Asian “flu” outbreaks in flocks of chickens indicate that humans have been infected who live or work in close proximity to those flocks of chickens

32. Avian Influenza may well be the pandemic in waiting

33. Even if an epidemic is not deliberately caused by an altered strain of influenza virus, an epidemic or pandemic originating from natural origins will more than likely occur

34. If Pandemic Influenza Came Today... • Up to 200 million people infected • Up to 50 million people requiring care • Up to 2 million hospitalizations • Between 100,000 and 500,000 deaths …just in the USA

36. “THE INFLUENZA CLOCK IS TICKING, WE JUST DON’T KNOW WHAT TIME IT IS” • Ed Marcuse, MD and past chairman, The National Vaccine Advisory Committee

37. SARS (SEVERE ACUTE RESPIRATORY SYNDROME)

38. A Novel Virus: SARS NEJM May 15, 2003

39. SARS-BASIC FACTS • SARS is an illness which can vary in severity and is caused by a Corona virus most likely of animal origin, e. g. civet • The disease is spread by large respiratory droplets from sneezing and coughing within a radius of 6 to 8 feet. • Incubation period-3 to 10 days • It can survive on surfaces up to 3 days but is easily killed by standard disinfectants

40. SARS: Summary Points - 1 • In retrospect epidemic started ~ November 2002 in Southern China • WHO issues “Global Alert” March 2002 • February 2003 very infectious patient infects many guests at Metropole Hotel in Hong Kong who in turn spread SARS to their own countries • World attention remained focused on SARS until global surveillance shows all chains of transmission interrupted ~ July 2003

41. MMWR March 28, 2003 / Vol. 52 / No. 12 Hong Kong Metropole Hotel index case. Example of a “super-spreader”.

42. Is there a small subset of SARS patients who account for a disproportionate share of transmission? MMWR May 9, 2003 / Vol. 52 / No. 18 - I Patients No: 1, 6, 35, 130&127 seemed to be “hypertransmitters”

43. SARS news: www.cnn.com ThursdayMay 15,2003 R. Ball, MD, MPH

44. WHO consensus document on the epidemiology of SARS : Selected conclusions • The report found no evidence that SARS is an airborne disease • Health Care Workers were at special risk, especially those involved with aerosol-generating procedures • The risk of transmission is greatest around day 10 of the illness • Children were rarely affected by SARS • The implications of the events at the Metropole Hotel are not yet fully understood

45. The Return of SARS--2004 • SARS reoccurred in China in 2004 • There were nine cases • WHO issued a Global Health Advisory • The outbreak was contained 5/18/04, but WHO advised continued vigilance

46. The return of SARS - 2004Summary Comments • SARS improved the ability of public health to conduct surveillance, investigate, and establish control measures for an infectious respiratory disease with (then) apparently pandemic potential • How extraordinary to have lived through the first global outbreak which was managed in real-time by means of public health measures, the Internet, and teleconferencing calls (e.g. between WHO, CDC, Hong-Kong, Singapore, Toronto, etc.)

47. The return of SARS - 2004Summary Comments • How extraordinary to have lived through the first global outbreak which was managed in real-time by means of public health measures, the Internet, and teleconferencing calls (e.g. between WHO, CDC, Hong-Kong, Singapore, Toronto, etc.)

48. SARS “over its peak” ? June 5 & 19,2003 R. Ball, MD, MPH

49. SARS: we’re “unprepared” www.gao.gov http://www.gao.gov/new.items/d031058t.pdf R. Ball, MD, MPH