1. Someday in the Spring, an Army private reported to the camp hospital before breakfast. He had a fever, sore, throat, headache... nothing serious. One minute later, another soldier showed up. By noon, the hospital had over a hundred cases; in a week, 500...

2. H1N1 Facts Are we facing another deadly pandemic? Carlos A. Aguilar

3. H1N1 Facts Introduction Introduction Influenza facts Influenza facts Glossary Glossary Background of previous pandemics Background of previous pandemics Viral evolution Viral evolution Conclusion Conclusion

4. Glossary Influenza. Colloquial flu/grippe. Acute infectious respiratory disease caused by Influenza viruses manifested by fatigue, fever and chills, a hacking cough, and body aches. Common cold. Upper respiratory infection caused by Coronavirus or Rhinovirus, manifested with nasal congestion, sore throat, itchy eyes.

5. Glossary Influenza A. Most common type of Influenza. Strains with high propensity of mutations, partly because they can infect various animals. Influenza virus. Mosaic of surface antigens: Hemagglutinin (19) and Neuraminidase (9) are used for nomenclature of strains. i.e. Avian strain H5N1 H1N1. Influenza A strain responsible for most seasonal outbreaks and comprises also the “Swine strain”

6. Glossary Seasonal influenza. Is a regularly recurring time period characterized by the prevalence of outbreaks of influenza during the cold half of the year in each hemisphere. Pandemic. Disease affecting the population of an extensive region, country, continent or global

7. Pandemic virus in 20 th Century 1918 “Spanish influenza” (H1N1) 40-50 million people died (675,000 in US) Cedar Rapids swine show 1957 “Asian influenza” (H2N2) Disappearance of H1N1 until 1977 70,000 deaths in the US 1968 “Hong Kong influenza” (H3N2) 34,000 deaths in the US

8. Viral background Viral adaptation to a new host species is a complex process Influenza A (H1N1) virus overcame barriers in 1918 to emerge from an avian source simultaneously in swine and humans 1931 R. Shoppe: adult human serum could neutralize the swine flu virus in mouse model 1931 R. Shoppe: adult human serum could neutralize the swine flu virus in mouse model

9. Robert B. Belshe, M.D. NEJM 353;21. Nov 24, 2005

10. Swine influenza in humans 1974: swine influenza isolation from a human, a patient with Hodgkin’s disease who lived on a pig farm 1976: Fort Dix outbreak, 230 cases/1 death triggered 40 million civilian vaccinations and 532 cases of the Guillain–Barré syndrome, including 32 deaths

11. Swine influenza in humans 1977: H1N1 reemergence in Soviet Union, Hong Kong, and northeastern China 1977 to present: Seasonal influenza predominant with 2 serotypes cocirculating: H1N1/H3N2 1979 to present: Reemergence of new swine virus 1998 triple reassortant swine influenza virus in 17- year-old boy in Wisconsin April 2009, the first cases of S-OIV

12. Shanta M. Zimmer, M.D., and Donald S. Burke, M.D. NEJM; 361:279-85. Jul 16, 2009

13. 2009 Lineage Virus Descent from the 1918 virus Survivors of 1918 pandemic protected Previous exposures to H1N1 may provide partial protection (1947 attenuated outbreak) Importance of vaccination Cell-mediated immunity may also play a role in competition among influenza strains

14. Shanta M. Zimmer, M.D., and Donald S. Burke, M.D. NEJM; 361:279-85. Jul 16, 2009

15. Conclusions Emergence of influenza A (H1N1) 91 years ago led to a disastrous global pandemic Virus is thought to have emerged simultaneously from birds into humans and swine

16. Conclusions In contrast, S-OIV probably emerged from swine into humans S-OIV shares three gene segments with current seasonal human influenza A (H1N1) virus and three segments with human seasonal influenza A (H3N2) virus. By inference this outbreak may not have the same impact as 1918