1. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings PowerPoint® Lectures Lectures by Greg Podgorski, Utah State University Preparing for a Pandemic Current Issues in Biology, Volume 4 Scientific American

2. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Concept Review Preparing for a Pandemic The occurrence of the next flu pandemic is not a question of if but of when. Pandemic flu bears little resemblance to common seasonal flu outbreaks. Influenza pandemics occur when influenza virus present in birds mutates into a strain that can infect and be transmitted among people.

3. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Concept Review Preparing for a Pandemic Flu pandemics emerge unpredictably, with the last three striking in 1918, 1957, and 1968. If the influenza virus replicates faster than our immune systems defend against it, the virus will cause severe and sometimes fatal illness. Scientists are concerned that the H5N1 strain of influenza that now infects birds and only a few people could mutate into the next pandemic strain.

4. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Concept Review Preparing for a Pandemic There are four lines of defense against pandemic flu: surveillance, vaccination, containment, and treatment. A troubling question is how well these measures could be deployed if public health workers are downed by the flu.

5. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Concept Review Preparing for a Pandemic Surveillance The spread of each outbreak and the evolution of the influenza virus must be monitored constantly. Three international organizations lead the surveillance effort for pandemic influenza. The next pandemic is most likely to start in Asia, where surveillance remains spotty.

6. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Concept Review Preparing for a Pandemic Surveillance The U.S. has a sophisticated surveillance system that funnels information to the Centers for Disease Control and Prevention (CDC). Even so, the CDC director acknowledges that “the system is not fast enough to take the isolation or quarantine action needed to manage avian flu.”

7. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Concept Review Preparing for a Pandemic Vaccines Economics, complacency, and influenza’s rapid mutation rate conspire against having an adequate supply of vaccine for emergent influenza strains. Influenza presents a moving target because of its rapid evolution through random mutations and the exchange of genes when two strains infect a single host. Many influenza strains circulate together, with each constantly evolving.

8. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Concept Review Preparing for a Pandemic Vaccines Vaccines must be matched against a specific strain and they require at least six months to produce. Two vaccinations given four weeks apart are needed for protection from pandemic flu. This means that effective protection for those first vaccinated requires at least 7 months from the start of vaccine development.

9. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Concept Review Preparing for a Pandemic Vaccines Vaccine supplies will be severely limited, so national pandemic plans need to prioritize who will be vaccinated and in what order. Economic factors partially account for vaccine shortage: There is little economic incentive for manufacturers to develop and stockpile vaccines against strains that may or may not turn into the next pandemic strain.

10. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Concept Review Preparing for a Pandemic Containment Time is of the essence in preventing the spread of a pandemic: to contain a pandemic strain, flu transmission must be controlled within 30 days of the first case. Flu moves with extraordinary speed because of its short incubation period: one day after infection, even before showing symptoms, a person may be infectious. Influenza’s speed means that it can never be stopped by isolating infected individuals and tracing their contacts.

11. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Concept Review Preparing for a Pandemic Containment A glimmer of hope comes from models that suggest that under particular conditions pandemic flu might be contained. One set of favorable conditions is widespread availability of a vaccine and antiviral drugs, and a rapid, aggressive, nationwide effort to control transmission within 30 days of the first case. Unfortunately, it is uncertain that these conditions could be met in a real-world outbreak, especially in areas where surveillance is poor.

12. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Concept Review Preparing for a Pandemic Containment If a pandemic strain is not contained, it is likely to circle the globe in two or three waves, each lasting several months, with peak impact in individual communities occurring about five weeks after the first outbreak. In a pandemic, non-pharmaceutical measures will be the primary defense.

13. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Concept Review Preparing for a Pandemic Containment The World Health Organization recommends surgical masks for patients and health workers, hand washing for the healthy, and a wait-and-see approach to implementing social distancing measures such as closing mass transit systems and schools.

14. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Concept Review Preparing for a Pandemic Treatment The death toll of the next pandemic will depend largely on the severity of the influenza strain. Common estimates are 10 million deaths for a mild strain and 100 million deaths for a severe strain. Rules of thumb are that 50% of people will be infected and between one- and two-thirds of these will fall ill. An estimated 4.7 million Americans will require hospitalization in a pandemic, this in a country with 1 million hospital beds.

15. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Concept Review Preparing for a Pandemic Treatment Different flu strains predominantly affect different groups. For example, annual flu has the greatest impact on the very young and old, those with chronic disease, and those with weakened immune systems. In contrast, the severe 1918 pandemic flu was most lethal to otherwise healthy adults in their 20’s and 30’s. If H5N1 becomes a pandemic influenza strain, it gives every indication of being a severe one.

16. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Concept Review Preparing for a Pandemic Treatment Little is known about the susceptibility of H5N1 to antiviral drugs. Even if a pandemic derivative of H5N1 could be treated effectively with antiviral drugs, the current drug supply is far too low to treat the estimated 25% of the U.S. population that would need them.

17. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Concept Review Preparing for a Pandemic Perspective We are better able to understand, monitor, contain, and treat pandemic influenza than at any time in the past. Even so, existing measures may be insufficient to diminish the next pandemic. The stronger our defenses, the better we will weather the storm when it strikes. “We have only one enemy, and that is complacency.” (Julie Gerberding, CDC Director)

18. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Preparing for a Pandemic Testing Your Comprehension Influenza’s rapid evolution is due in part to a) its use of DNA instead of RNA to encode genetic information b) the exchange of genes that occurs when two strains infect a single host c) the tightness of the protein coat that surrounds the influenza genome d) the ability of all influenza strains to be rapidly transmitted from one individual to another

19. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Preparing for a Pandemic Testing Your Comprehension Influenza’s rapid evolution is due in part to b) the exchange of genes that occurs when two strains infect a single host

20. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Preparing for a Pandemic Testing Your Comprehension The next pandemic is most likely to start in a) Asia b) Africa c) North America d) South America

21. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Preparing for a Pandemic Testing Your Comprehension The next pandemic is most likely to start in a) Asia

22. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Preparing for a Pandemic Testing Your Comprehension Epidemiologists estimate that a severe influenza pandemic may kill as many as people worldwide. a) 100s of thousands of b) 1–2 million c) 100s of millions of d) 2–3 billion

23. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Preparing for a Pandemic Testing Your Comprehension Epidemiologists estimate that a severe influenza pandemic may kill as many as people worldwide. c) 100s of millions of

24. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Preparing for a Pandemic Testing Your Comprehension For most people, the primary line of defense against a flu pandemic will be a) vaccination b) antiviral drugs c) antibiotics d) non-pharmaceutical measures

25. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Preparing for a Pandemic Testing Your Comprehension For most people, the primary line of defense against a flu pandemic will be d) non-pharmaceutical measures

26. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Preparing for a Pandemic Biology and Society In the likely case that influenza vaccines and antiviral drugs are in short supply, the elderly and chronically ill should not be first in line for these protective treatments. Strongly Agree Strongly Disagree A. E. C. B. D.

27. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Preparing for a Pandemic Thinking About Science Imagine that the influenza virus H gene is on one strand of RNA and that the N gene is on a separate strand of RNA. The H gene comes in two forms, H1 and H2, and the N gene comes in the N1 and N2 forms. Two strains of influenza virus infect a cell. One strain is H1N1 and the other is H2N2. If influenza viruses always contain one N and one H gene, how many different kinds of influenza viruses can be produced from the infected cell? a) 1 b) 2 c) 4 d) 8

28. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Preparing for a Pandemic Thinking About Science Imagine that the influenza virus H gene is on one strand of RNA and that the N gene is on a separate strand of RNA. The H gene comes in two forms, H1 and H2, and the N gene comes in the N1 and N2 forms. Two strains of influenza virus infect a cell. One strain is H1N1 and the other is H2N2. If influenza viruses always contain one N and one H gene, how many different kinds of influenza viruses can be produced from the infected cell? c) 4

29. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Preparing for a Pandemic Interpreting Data and Graphs What is one likely explanation for regions of the country with a low flu incidence 60 days after the outbreak began? a) The outbreak began in these regions and the disease has run its course. b) No people live in these regions. c) Low population density. d) A high frequency of resistant individuals.

30. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Preparing for a Pandemic Interpreting Data and Graphs What is one likely explanation for regions of the country with a low flu incidence 60 days after the outbreak began? c) Low population density.