Where Health Care Meets Policy. with Dr. Mike Magee

Transcription

1 Where Health Care Meets Policy with Dr. Mike Magee

2 The Threat of Bird Flu

3 Understanding Bird Flu and the Influenza Virus 3 types of the influenza virus: A, B and C reflect differences in the M protein on the envelope that contains the virus A influenza viruses cause human and bird flu outbreaks contain 8-segment RNA strand segments break apart during replication to mix and reassort potential for constant evolution is built in sub-typed based on activity in envelope s glycoproteins: 1] hemagglutinin activity (H): 16 known varieties 2] neuraminidase activity (N): 9 known varieties Shorthand names have an H and N number (H1N1) Sources: Infectious Diseases Society of America Web site. Avian Influenza (Bird Flu): Implications for Human Disease. Centers for Disease Control and Prevention Web site. Information about Avian Influenza (Bird Flue) and Avian Influenza A (H5N1) Virus. Hien TT. De Jong M, Farrar J. Avian influenza a challenge to global health care structures. NEJM. 2004;351:

4 Bird Flu and Human Flu Have a Complex and Inter-related Story 3 influenza A viruses associated with 20 th century human pandemics all have genetic components originally housed in viruses in birds 1918 H1N1 virus killed 20 to 40 million people worldwide 1957 H2N2 and 1968 H3N2 viruses each responsible for more than 1 million deaths Now, in 2005, all eyes are focused on H5N1 bird flu Source: Hien TT. De Jong M, Farrar J. Avian influenza a challenge to global health care structures. NEJM. 2004;351: Hastings M, Guteri F. Bird-Flu Challenge. MSNBC.com. Dec. 13, 2004.

5 The Influenza A Virus Appears Most In Wild Bird Populations Spreads rapidly through exchange of mucus or feces, without creating sickness or death in these species Once transferred to domestic birds (chickens, ducks and turkeys), spreads explosively is frequently lethal Virus mutates rapidly in large groups of closely contained birds Has ability to jump to other species, such as pigs Secondary carriers become mixing pots for more varieties, increasing chances that other mammals, including humans, will become vulnerable. Sources: Centers for Disease Control and Prevention Web site. Information about Avian Influenza (Bird Flue) and Avian Influenza A (H5N1) Virus. Fouchier R, Kuiken T, Rimmelzwaan G, Osterhaus A. Global task force for influenza. Nature. 2005;435:

6 The H5N1 Bird Flu Has Infected Humans and Continues to Evolve First identified in South African wild terns in 1961 Spread naturally among global bird populations over 4 decades Appeared in poultry populations in 2003 outbreak in 8 countries in Asia: Cambodia, China, Indonesia, Japan, Laos, South Korea, Thailand, and Vietnam loss of more than 100 million domestic birds Outbreak appeared under control until June of 2004 when it reappeared in 4 of the same countries and Malaysia Sources: Infectious Diseases Society of America Web site. Avian Influenza (Bird Flu): Implications for Human Disease. Centers for Disease Control and Prevention Web site. Information about Avian Influenza (Bird Flue) and Avian Influenza A (H5N1) Virus. WNYC. The Leonard Lopate Show. Underreported: Avian Flu. July 14, 2005.

7 Sources: Infectious Diseases Society of America Web site. Avian Influenza (Bird Flu): Implications for Human Disease. Centers for Disease Control and Prevention Web site. Information about Avian Influenza (Bird Flue) and Avian Influenza A (H5N1) Virus. Hien TT. De Jong M, Farrar J. Avian influenza a challenge to global health care structures. NEJM. 2004;351: Bird Flu in Humans H5N1 first infected a human population in Hong Kong in documented cases, 6 deaths reappeared in 2 cases, causing 1 death in 2003 soon broke out in Vietnam, Thailand and Cambodia As of June 2005: 100 documented human cases 54 percent mortality rate transmission is result of direct contact with infected poultry What constitutes a pandemic? 1] highly virulent organism 2] lack of human immunity to the organism 3] ability to easily transmit from human to human H5N1 has the first two, but not the third (at least not yet)

8 Concerns Are High: Studies Demonstrate Continued Evolution Host range of H5N1 is expanding includes pigs, horses, cats, tigers, leopards, whales and seals Expansion of the domestic bird population in Asia China: domestic chicken population increase: 8 million to 13 billion More domestic pigs, which are catalytic mixers of genetic brews Human-to-human transmission has occurred in a documented case of child to mother to aunt in Thailand Spread stopped there, suggesting virus does not yet have capability to readily jump from one human to the next. Sources: Infectious Diseases Society of America Web site. Avian Influenza (Bird Flu): Implications for Human Disease. Hien TT. De Jong M, Farrar J. Avian influenza a challenge to global health care structures. NEJM. 2004;351: WNYC. The Leonard Lopate Show. Underreported: Avian Flu. July 14, Ungchusak K, Auewarakul P, Dowell SF, Kitphati R, Auwanit W, et al. Probable person-to-person transmission of avian influenza A (H5N1). NEJM. 2005;352:

9 Our Capacity to Diagnose and Manage an H5N1 Pandemic is Less than Adequate Needs Excellent surveillance: clinical, scientific and technologic capacity Knowledge sharing The will to act (quickly) at first sign of human-to-human transmission Concerns H5N1 is already resistant to two of four common anti-viral drugs Our supply of the two non-resistant drugs is woefully inadequate Sources: Centers for Disease Control and Prevention Web site. Information about Avian Influenza (Bird Flue) and Avian Influenza A (H5N1) Virus. World Health Organization. Report by the Secretariat. Avian influenza and human health. April 8, 2004.

10 The Good News Aug. 7: Health officials announced success in an initial test of a human vaccine Realities Existence of vaccine is not enough to prevent a worldwide pandemic More testing is required before vaccine can be offered to public Vaccine made in chicken eggs: successful mass production dependent on available eggs Obstacles include organizational system for distribution Sources: Altman LK. Avian Flu Vaccine Called Effective in Human Testing. The New York Times. Aug. 7, Altman LK, Bradsher K. A Successful Vaccine Alone Is Not Enough to Prevent Avian Flu Epidemic. The New York Times. Aug. 8, 2005.

11 Managing the Real Risk of Bird Flu Requirements Global cooperation Expanded surveillance Expanded capacity H5N1 tracking worldwide Agree on a research plan Share knowledge Be ready to intervene Poultry Surveillance of all subtypes Modifying production and distribution, and strict enforcement Humans Broad surveillance / detection Cluster investigation Contact tracking Targeted use of anti-virals Continued vaccine R&D Travel restrictions when appropriate Human transmission of bird flu is predictable and therefore manageable. Failure to take action could be a mistake of historic proportions.

12 The Threat of Bird Flu Release Date: 8/24/2005 with Dr. Mike Magee