Preparing for Microbial Threats to Health: What Every Professional Should Know

Transcription

1 Preparing for Microbial Threats to Health: What Every Professional Should Know Tomás J. Aragón, MD, DrPH Health Officer, City & County of San Francisco Director, Population Health Division (PHD), SFDPH June 9, 2014 Tomás J. Aragón, MD, DrPH (SFDPH) Preparing for Microbial Threats to Health June 9, / 33

2 Acknowledgments Robert S. Nakao, Executive Publisher, Advantage Business Media SFDPH Population Health Division leadership and staff Association of Bay Area Health Officials (ABAHO) California Conference of Local Health Officers (CCLHO) Center for Infectious Disease & Emergency Readiness* Cal PREPARE Systems Research Center* California Department of Public Health (CDPH) National Association of County & City Health Officials (NACCHO) Centers for Disease Control and Prevention (CDC) * UC Berkeley School of Public Health Tomás J. Aragón, MD, DrPH (SFDPH) Preparing for Microbial Threats to Health June 9, / 33

3 Contagion The movie! vs. Contagion Your reality! Glass RJ, et al. Targeted social distancing design for pandemic influenza. Emerg Infect Dis Nov;12(11): PubMed: Tomás J. Aragón, MD, DrPH (SFDPH) Preparing for Microbial Threats to Health June 9, / 33

4 Middle East Respiratory Syndrome (MERS), June, 2014 Deadly Virus s Spread Raises Alarms in Mideast: Saudis Defend Approach to MERS Outbreak, Even as Cases Increase. Wall Street Journal Online, April 13, 2014 Saudi Ministry of Health, June 7, 2014 Tomás J. Aragón, MD, DrPH (SFDPH) Preparing for Microbial Threats to Health June 9, / 33

5 Overview 1 Challenge of complexity 2 Controlling microbial threats Transmission mechanisms Transmission dynamics Transmission containment 3 Integrated model for controlling microbial threats Tomás J. Aragón, MD, DrPH (SFDPH) Preparing for Microbial Threats to Health June 9, / 33

6 Well established cause of outbreaks! Tomás J. Aragón, MD, DrPH (SFDPH) Preparing for Microbial Threats to Health June 9, / 33

7 Well established response to outbreaks! Tomás J. Aragón, MD, DrPH (SFDPH) Preparing for Microbial Threats to Health June 9, / 33

8 Challenge of complexity SFDPH PHD Controlling Infectious Diseases (CID) Model Addressing complexity with a simple framework for action (Tomás J. Aragón, 2014) The PHD CID Model The PHD CID model is an integrated model for preventing and controlling infectious diseases. Also consider the following: (1) Is there asymptomatic infectiousness? (latent period is shorter than incubation period), (2) What is the generation time?, (3) What are the ethical considerations?, and (4) Do you have the political and logistical support to be successful? A) Microbial Agent in B) Reservoir or C) Source Reservoir / Source 1 Air 2 Water 3 Food 4 People 5 Animals & vectors 6 Vehicles 7 Soil & debris D) Portal of Exit E) Mode of Transmission Modes of transmission 1 Contact - direct 2 Contact - indirect 3 Droplets 4 Airborne 5 Vehicle-borne 6 Vector-borne 7 Vertical (mom-child) Transmission Containment Strategies 1 Reduce contact rate 2 Reduce fraction of population that is infectious 3 Reduce biological infectiousness F) Portal of Entry G) Susceptible Host The 7 Habits of Uninfected People 1. Safe consumption 2 Personal hygiene 3 Covering your cough 4 Getting vaccinated 5 Using protection 6 Reducing special risks 7 Basic infection control 4 Reduce biological susceptibility 5 Interrupt transmission (physical, chemical) 6 Reduce fraction of population that is susceptible Tomás J. Aragón, MD, DrPH (SFDPH) Preparing for Microbial Threats to Health June 9, / 33

9 Challenge of complexity Complexity and why it matters What is a complex system? 1 A population of diverse agents, all of which are 2 connected, with behaviors and actions that are 3 interdependent, and that exhibit 4 adaptation and learning. Why do we care? Often unpredictable Can produce large events Can withstand substantial trauma Can evolve along divergent pathways Can produce tipping points (e.g., epidemics) Can produce emergent phenomena (e.g., self-organization) Tomás J. Aragón, MD, DrPH (SFDPH) Preparing for Microbial Threats to Health June 9, / 33

10 Challenge of complexity Spread of novel influenza A (H1N1) via global air travel Destination cities and corresponding volumes of international passengers arriving from México between March 1 and April 30, A total of 2.35 million passengers flew from México to 1018 cities in 164 countries. Source: Khan et al. (2009), PMID Tomás J. Aragón, MD, DrPH (SFDPH) Preparing for Microbial Threats to Health June 9, / 33

11 Challenge of complexity Mitigating complexity Be humble Expect to fail Expect the unexpected Expect unintended consequences Expect big events and tipping points (e.g., epidemics) Beware of pathway dependence (irreversible evolutionary divergence) Harnessing complexity Balance exploration (learning) and exploitation (execution) Develop/use simple frameworks for action (this talk!) Design for agility, adaptability, and responsiveness Develop/use simple rules that spread Every failure is a learning opportunity Tomás J. Aragón, MD, DrPH (SFDPH) Preparing for Microbial Threats to Health June 9, / 33

12 Concepts for controlling infectious diseases Transmission mechanisms 1 Chain model of infectious diseases 2 Natural history of infection and infectiousness 3 Convergence model of microbial threats Transmission dynamics 1 Reproductive number 2 Infection rate among susceptibles 3 Generation time Transmission containment 1 Control points, strategies, and measures Tomás J. Aragón, MD, DrPH (SFDPH) Preparing for Microbial Threats to Health June 9, / 33

13 Transmission mechanisms Chain model of infectious diseases Chain model A) Microbial agent B) Reservoir / Source C) Portal of exit D) Mode of transmission E) Portal of entry F) Susceptible host A) Microbial Agent in B) Reservoir or C) Source D) Portal of Exit E) Mode of Transmission F) Portal of Entry G) Susceptible Host Tomás J. Aragón, MD, DrPH (SFDPH) Preparing for Microbial Threats to Health June 9, / 33

14 Transmission mechanisms Chain model Reservoir / Source Reservoir / Source Humans Animals Environment A) Microbial Agent in B) Reservoir or C) Source D) Portal of Exit E) Mode of Transmission F) Portal of Entry G) Susceptible Host A reservoir can always be a source, but not all sources are reservoirs. Reservoir / Source 1 Air 2 Water 3 Food 4 People 5 Animals & vectors 6 Vehicles 7 Soil & debris Modes of transmission 1 Contact - direct 2 Contact - indirect 3 Droplets 4 Airborne 5 Vehicle-borne 6 Vector-borne 7 Vertical (mom-child) The 7 Habits of Uninfected People 1. Safe consumption 2 Personal hygiene 3 Covering your cough 4 Getting vaccinated 5 Using protection 6 Reducing special risks 7 Basic infection control Tomás J. Aragón, MD, DrPH (SFDPH) Preparing for Microbial Threats to Health June 9, / 33

15 Transmission mechanisms Chain model Modes of Transmission Modes of transmission 1 Contact direct D) Portal of Exit E) Mode of Transmission F) Portal of Entry 2 Contact indirect 3 Droplet 4 Airborne 5 Vehicle-borne (food) A) Microbial Agent in B) Reservoir or C) Source G) Susceptible Host 6 Vector-borne (bugs) 7 Vertical (mom-child) Reservoir / Source 1 Air 2 Water 3 Food 4 People 5 Animals & vectors 6 Vehicles 7 Soil & debris Modes of transmission 1 Contact - direct 2 Contact - indirect 3 Droplets 4 Airborne 5 Vehicle-borne 6 Vector-borne 7 Vertical (mom-child) The 7 Habits of Uninfected People 1. Safe consumption 2 Personal hygiene 3 Covering your cough 4 Getting vaccinated 5 Using protection 6 Reducing special risks 7 Basic infection control Tomás J. Aragón, MD, DrPH (SFDPH) Preparing for Microbial Threats to Health June 9, / 33

16 Transmission mechanisms Chain model The 7 Habits of Uninfected People The 7 Habits of Uninfected People 1 Safe consumption 2 Personal hygiene 3 Covering your cough A) Microbial Agent in B) Reservoir or C) Source D) Portal of Exit E) Mode of Transmission F) Portal of Entry G) Susceptible Host 4 Getting vaccinated 5 Using protection 6 Reducing special risks 7 Basic infection control Reservoir / Source 1 Air 2 Water 3 Food 4 People 5 Animals & vectors 6 Vehicles 7 Soil & debris Modes of transmission 1 Contact - direct 2 Contact - indirect 3 Droplets 4 Airborne 5 Vehicle-borne 6 Vector-borne 7 Vertical (mom-child) The 7 Habits of Uninfected People 1. Safe consumption 2 Personal hygiene 3 Covering your cough 4 Getting vaccinated 5 Using protection 6 Reducing special risks 7 Basic infection control Tomás J. Aragón, MD, DrPH (SFDPH) Preparing for Microbial Threats to Health June 9, / 33

17 Transmission mechanisms Good infection control starts with common sense: Cover the source! Source: American Society of Microbiology Tomás J. Aragón, MD, DrPH (SFDPH) Preparing for Microbial Threats to Health June 9, / 33

18 Transmission mechanisms Disease scare at San Jose airport: 5 on flight from Asia examined none found with SARS I San Francisco Chronicle, Wednesday, April 2, 2003 In a false alarm heard round the world, the Santa Clara County health system jumped into high alert Tuesday morning when an American Airlines flight from Tokyo radioed that it might have five cases of the mysterious flulike illness known as SARS on board. [Joan] Krizman said she had no hard feelings about being treated as a potential health threat. The couple had just completed an exhausting, monthlong journey that included stops in Vietnam, Thailand and Hong Kong three Southeast Asian hot spots for SARS. There were four fire trucks and eight police cars and four or five ambulances, she recalled. I couldn t believe it. I thought, Wow! What s going on here? Little did I know that we were to be the victims. Tomás J. Aragón, MD, DrPH (SFDPH) Preparing for Microbial Threats to Health June 9, / 33

19 Transmission mechanisms Disease scare at San Jose airport: 5 on flight from Asia examined none found with SARS II The couple were asked twice to go to Valley Medical Center, and twice they politely declined. And then, Krizman said, they soon opened up the ambulance doors and said, sorry, we re taking you to the hospital. At the hospital, according to Krizman, we were the only ones there not wearing masks. When word got out just who they were, she said, People started running like crazy, like we were the bubonic plague. They put us in a room full of people with plastic boots and face shields and masks. Tomás J. Aragón, MD, DrPH (SFDPH) Preparing for Microbial Threats to Health June 9, / 33

20 Transmission mechanisms Nurse wearing N-95 respirator outside of intensive care unit Associated Press: In a ward at Sunnybrook and Womens Hospital in Toronto, a nurse waits outside the door of a patient diagnosed with the illness [SARS]. Tomás J. Aragón, MD, DrPH (SFDPH) Preparing for Microbial Threats to Health June 9, / 33

21 Transmission mechanisms Public-devised infection control, SARS outbreak, 2003 Tomás J. Aragón, MD, DrPH (SFDPH) Preparing for Microbial Threats to Health June 9, / 33

22 Transmission mechanisms Infection control practices, SARS outbreak, 2003 Reuters: An Indian woman diagnosed with SARS sits on her bed at the Doctor Naidu Infectious Diseases Hospital in the western city of Pune. Doctors reported India s first case of the disease in a marine engineer from the western coastal state of Goa on Friday, April 18, Tomás J. Aragón, MD, DrPH (SFDPH) Preparing for Microbial Threats to Health June 9, / 33

23 Transmission mechanisms WHO: Infection control gaps helped fuel UAE MERS surge CIDRAP News, June 6, 2014 Infection control breaches led a list of factors that contributed to the April surge of MERS-CoV cases in the United Arab Emirates (UAE), the World Health Organization (WHO) said today after a team of WHO and partner experts spent 5 days assessing the situation there. Source: WHO finds hospital breaches worsened MERS outbreak in UAE. Source: ArabianBusiness.com, June 7, 2014 Tomás J. Aragón, MD, DrPH (SFDPH) Preparing for Microbial Threats to Health June 9, / 33

24 Transmission mechanisms Natural history of infection and infectiousness (A vs. B) A Time of infection Symptomatic, Not infectious Susceptible Latent period Infectious period Non-infectious Incubation period Symptomatic period Non-diseased B Time of infection No symptoms, Infectious Susceptible Latent period Infectious period Non-infectious Incubation period Symptomatic period Non-diseased When the latent period is shorter than the incubation period (B), an infected person becomes infectious before symptom onset. Tomás J. Aragón, MD, DrPH (SFDPH) Preparing for Microbial Threats to Health June 9, / 33

25 Transmission mechanisms Convergence model for human-microbe interaction Institute of Medicine. Microbial threats to health: Emergence, Detection, and Response. National Academy Press, 2003 Tomás J. Aragón, MD, DrPH (SFDPH) Preparing for Microbial Threats to Health June 9, / 33

26 Transmission dynamics Epidemic curve in action, SARS outbreak, 2003 Number of probable cases of severe acute respiratory syndrome, by date of fever onset and reported source of infection, Singapore, Feb 25-Apr 30, Source: CDC MMWR (2003) PMID: Tomás J. Aragón, MD, DrPH (SFDPH) Preparing for Microbial Threats to Health June 9, / 33

27 Transmission dynamics Reproductive number in action, SARS outbreak, 2003 Probable cases of severe acute respiratory syndrome, by reported source of infection, Singapore, Feb 25-Apr 30, Source: CDC MMWR (2003) PMID: Tomás J. Aragón, MD, DrPH (SFDPH) Preparing for Microbial Threats to Health June 9, / 33

28 Transmission dynamics In Contagion, Dr. Erin Mears (Kate Winslet) explains R 0 Contagion is a 2011 public health thriller directed by Steven Soderbergh. Source (figure): PMID: Tomás J. Aragón, MD, DrPH (SFDPH) Preparing for Microbial Threats to Health June 9, / 33

29 Transmission dynamics Dynamics: Reproductive number and infection rate Basic reproductive number R 0 = d c p Transmission probability (p) Biologic infectiousness Biologic susceptibility Interruptors (e.g., PPE) Effective reproductive number R(t) = R 0 x(t) Infection rate among susceptibles I(t) = c p P (t) Source (figure): PMID: d = duration of infectiousness c = contact rate p = transmission probability x = fraction of population that is susceptible P = fraction of population that is infectious Tomás J. Aragón, MD, DrPH (SFDPH) Preparing for Microbial Threats to Health June 9, / 33

30 Transmission dynamics Reproductive number vs. Infection rate in susceptibles D) Portal of Exit E) Mode of Transmission F) Portal of Entry d = duration of infectiousness c = contact rate p = transmission probability A) Microbial Agent in B) Reservoir or C) Source Transmission probability (p) G) Susceptible Host x = fraction of population that is susceptible P = fraction of population that is infectious Fraction of population that is infectious (P) Duration of infectiousness (d) Contact rate (c) Fraction of population that is susceptible (x) Tomás J. Aragón, MD, DrPH (SFDPH) Preparing for Microbial Threats to Health June 9, / 33

31 Transmission containment Transmission containment Control strategies 1 Reduce contact rate (c) 2 Reduce fraction of population that is infectious (P ) 3 Reduce biological infectiousness (affects p) 4 Reduce biological susceptibility (affects p) 5 Interrupt transmission (physical, chemical) (affects p) 6 Reduce fraction of population that is susceptible (x) Control measures... are interventions designed to address control strategies. Always consider mutliple perspectives: host, agent, infectious sources, and environment (physical, social, economic, political, etc.) Tomás J. Aragón, MD, DrPH (SFDPH) Preparing for Microbial Threats to Health June 9, / 33

32 Integrated model for controlling microbial threats SFDPH PHD Controlling Infectious Diseases (CID) Model Transmission mechanisms, dynamics, and containment (Tomás J. Aragón, 2014) The PHD CID Model The PHD CID model is an integrated model for preventing and controlling infectious diseases. Also consider the following: (1) Is there asymptomatic infectiousness? (latent period is shorter than incubation period), (2) What is the generation time?, (3) What are the ethical considerations?, and (4) Do you have the political and logistical support to be successful? A) Microbial Agent in B) Reservoir or C) Source Reservoir / Source 1 Air 2 Water 3 Food 4 People 5 Animals & vectors 6 Vehicles 7 Soil & debris D) Portal of Exit E) Mode of Transmission Modes of transmission 1 Contact - direct 2 Contact - indirect 3 Droplets 4 Airborne 5 Vehicle-borne 6 Vector-borne 7 Vertical (mom-child) Transmission Containment Strategies 1 Reduce contact rate 2 Reduce fraction of population that is infectious 3 Reduce biological infectiousness F) Portal of Entry G) Susceptible Host The 7 Habits of Uninfected People 1. Safe consumption 2 Personal hygiene 3 Covering your cough 4 Getting vaccinated 5 Using protection 6 Reducing special risks 7 Basic infection control 4 Reduce biological susceptibility 5 Interrupt transmission (physical, chemical) 6 Reduce fraction of population that is susceptible Tomás J. Aragón, MD, DrPH (SFDPH) Preparing for Microbial Threats to Health June 9, / 33

33 Integrated model for controlling microbial threats Thank you! Any questions? Tomás J. Aragón, MD, DrPH (SFDPH) Preparing for Microbial Threats to Health June 9, / 33