Basics of Avian and Pandemic Influenza

1. Basics of Avian and Pandemic Influenza

2. The Pandemic Clock is ticking…we just don’t know what time it is. Will pandemic flu strike again? • Edgar Marcus • University of Washington School of Medicine

3. The “Forgotten Pandemic” • The influenza pandemic of 1918-19 killed more humans than any other disease in a period of similar duration in the history of the world. Alfred W. Crosby, historian & author

4. Influenza pandemics in the20th century 1918: “Spanish Flu” 1957: “Asian Flu” 1968: “Hong Kong Flu” 50 million deaths 1-4 million deaths 1-4 million deaths

5. An Influenza Ward during the 1918: “Spanish Flu” Avian strain of influenza virus Virus was similar to current bird flu virus Spread around the globe in 4-6 months Infected between 25-30% of the world population Killed 40-100 million world-wide Majority of deaths in persons 18 to 40 years old

6. Influenza pandemics are recurring events • Influenza pandemic is NOT a one-off event. • They are regular events that occur a few times per century. • As long as the influenza virus continuestomutate we will continue to have influenza pandemics. • We cannot be sure exactly when the next one will be, but experts agree it will happen eventually. • The H5N1 Avian Influenza virus currently circulating in birds is the No.1 candidate for causing the next pandemic.

7. A Pandemic WILL occur: the question is “when and how severe will it be”?

8. WHO Situational Assessment as at May 2006 • Risk of Pandemic is great • The risk will persist • The evolution of the threat cannot be predicted • The early warning systems are weak • Reduction of morb/mort impeded by inadequate medical supplies • Preparation is the best protection

9. H5N1 - The Basics • Avian influenza H5N1 virus in poultry flocks • Aggressive infection - quickly kills whole flocks • Can infect humans - mainly only people living/working with poultry • Over 200 people infected - more than half have died (mortality rate >50%!!!!) • Cannot yet easily spread from person to person H5N1 has similarities to 1918-19 virus

10. THE DISEASE IN HUMANS • Influenza viruses are normallyhighly species-specific, meaning that viruses that infect an individual species (humans, certain species of birds, pigs, horses, and seals), and only rarely spill over to cause infection in other species. • Of the hundreds of strains of avian influenza A viruses, only four are known to have caused human infections: H5N1, H7N3, H7N7, and H9N2. In general, human infection with these viruses has resulted in mild symptoms and very little severe illness, with one notable exception: the highly pathogenic H5N1 virus.

11. H5N1--great concern for human health • First, the H5N1 virus has caused the greatest number of human deaths. • The virus has met all prerequisites for the start of a pandemic save one: an ability to spread efficiently among humans.

12. H5N1 - The Basics • An Influenza Virus must have three attributes to become a Pandemic Virus: • A novel (new) virus which humans have no immunity  • The virus causes significant human illness and death  • The virus can spread easily from person to person x • Avian Flu H5N1 has 2 out of 3 today…

13. H5N1 - The Basics • An Influenza Virus must have three attributes to become a Pandemic Virus: • A novel (new) virus which humans have no immunity  • The virus causes significant human illness and death  • The virus can spread easily from person to personx • Avian Flu H5N1 has 2 out of 3 today…

14. × × 禽流感在公共衛生的重要性 在20世紀時的三次重大「世界性大流行」均與其病毒來自「禽類」有關。若張三感染了「『禽』流感病毒（紅色基因）」而他的親友李四卻感染「『人』流感病毒（藍色基因）」，那重新洗牌八段藍色基因與八段紅色基因，容易產生一種『新』型病毒是原來人的抗體無法抵擋的，卻又可在人群中傳播。 禽流感病毒人流感病毒新型流感病

15. Genetic drift • A change that occurs on the molecular level to effect a change in the antigenic properties of a bacteria or virus. • Antigenic drift occurs naturally and more rapidly in certain viruses (for example HIV). • It is antigenic drift which complicates the development of an effective HIV (AIDS) vaccine.

16. As the human influenza strains are continually evolving via these mutations, the virus is able to escapefromthehumanimmune response and cause epidemics. For this reason, manufacturers must change the composition of the influenza vaccine on an annual basis in order to ensure an accuratematch is achieved with the circulatingviralstrains

17. Genetic shift • Antigenic shift is the process by which different strains of a virus, (or different viruses), combine to form a new subtype • having a mixture of the surface antigensof the two original strains.

18. What is the difference between Antigenic shift and antigenic drift? Antigenic drift is the natural mutation over time of known strains of influenza (or other things, in a more general sense) which may lead to a loss of immunity, or in vaccine mismatch. Antigenic drift occurs in all types of influenza including influenza A, B and C. Antigenic shift, however, occurs only in influenza A because it infects more than just humans.Affected species include other mammals and birds, giving influenza A the opportunity for a major reorganization of surface antigens

19. Antigenic shift vs antigenic drift: Antigenic drift is the natural mutation over time of known strains of influenza (or other things, in a more general sense) which may lead to a loss of immunity, or in vaccine mismatch. Antigenic drift occurs in all types of influenza including influenza A, B and C. Antigenic shift, however, occurs only in influenza A because it infects more than just humans.Affected species include other mammals and birds, giving influenza A the opportunity for a major reorganization of surface antigens.

20. How is Influenza Spread? • Infectivity period: 1 day before, 14 days after • 1. Contact transmission: • Direct - Kissing • Indirect – Sharing • 2. Mainly by “droplet” spread: • Coughing, sneezing and talking • Mucous membranes • Virus active on hard surfaces for 48 hours • 3. “Aerosol” spread: • Unusual but possible in very crowded conditions

21. WHO Classification of Pandemic Phases

22. H5N1 Avian Flu – where is it now? • Human infections (as at 8 May 2006): • Turkey (12 cases, 4 deaths) • Vietnam (93 cases, 42 deaths) • Indonesia (33 cases, 25 deaths) • Cambodia (6 cases, 6 deaths) • Thailand (22 cases, 14 deaths) • China (18 cases, 12 deaths) • Iraq (2 cases, 2 deaths) • Azerbaijan (8 cases, 5 deaths) • Egypt (13 cases, 5 deaths)

25. Prevention and control of Avian Flu

26. Vaccines: the first line of defence Annual influenza vaccination is now recommended for the following groups • persons at high risk for influenza-related complications • persons who live with or care for persons at high risk • health-care workers.

27. Depopulation of farms and markets

28. PILLARS OF THE STRATEGY • Preparedness and Communication • Surveillance and Detection • Response and Containment

29. H7N9 Influenza A(H7N9) is one of a subgroup of influenza viruses that normally circulate among birds. Until recently, this virus had not been seen in people. However, human infections have now been detected. The disease is of concern because most patients have been severely ill. There is no indication thus far that it can be transmitted between people, but both animal-to-human and human-to-human routes of transmission are being actively investigated. Dr Margaret Chan Director-General of WHO Courtesy of WHO Collaborating Centre for Reference and Research on Influenza, National Institute of Infectious Diseases, Japan

30. Hong Kong Quarantines 19 People After Second Case of H7N9 Disease Outbreak News • Hong Kong health officials have quarantined 19 people who had contact with an 80-year-old man confirmed to have the city’s second case of H7N9 influenza, which has killed 45 people in China this year. Bloomberg news Dec 8, 2013

31. SARS

32. Pandemic Influenza is different to SARS • Many institutions are using their SARS plan as the basis for their pandemic influenza plan. • But SARS is different to pandemic influenza:

33. 咳嗽禮節

34. Thank You