Avian Flu Yurij Kobasa & Ambrish Patel Overview 1. Background Information 2. Brief overview of genome structure 3. Origin/History 4. Geographical Distribution 5. Pandemic Nature 6. Diseases Caused 7. Treatment & Vaccines Background Information • Envelope with surface proteins, a matrix protein, a nucleoprotein complex, a nucleocapsid, and a polymerase complex; can be spherical or filamentous Background Information • There are many different subtypes of type A influenza viruses, classified by their different surface proteins, Hemagglutinin [HA] and Neuraminidase [NA] • Hemagluttinin is the protein that allows the influenza virus to bind to cells; it is the major virulence factor for influenza. • Neuraminidase is a receptor destroying enzyme, also called sialidase. Background Information • There are 16 different HA proteins and 9 different NA proteins • All known subtypes of flu A viruses can be found in birds; usually don’t infect humans • There are only three known A subtypes of human flu viruses (H1N1, H1N2, and H3N2) • Influenza A viruses are constantly mutating and adapting over time to infect and spread among humans. Genomic Structure • Segmented • 8 linear, negative sensed, ssRNA segments, totaling for 10-14Kb • 5' and 3' terminal repeats of 11-14bp. • Each segment has its own nucleocapsid, all nucleocapsids are surrounded by one envelope. Origin/History • First H5N1 known crossover from birds to humans was in 1997 in Hong Kong - 18 people were infected and 6 died • In January of 2004 an outbreak occurred in poultry farms in Vietnam @ Thailand, and within weeks it spread to over 10 surrounding countries in Asia (including China, South Korea, Indonesia, Japan). • In February it was isolated in pigs, raising fears of new variant strains. It was contained by March, after 23 people died and over 40 million chickens were culled. Origin/History • Human to human transmission has been documented in Vietnam and Thailand, but only familial, or to nurses caring for these patients. • When the virus first infected humans the mortality rate was ~65%. • Since then it has gone down to ~35%. • This might indicate that the virus is now able to infect more people and spread more quickly through the population, and becoming a global pandemic with a very high number of deaths despite a low mortality rate. Geographical Distribution • August 2005 - Kazakhstan, Mongolia, western Russia report outbreaks of H5N1 in poultry • China reported over 1000 migratory birds were found dead, meaning it could now spread into Africa and the Middle East. • September 2005 - UN Health representative David Nabarro announced that a global pandemic could occur at any time, killing between 5 and 150 million people. (23% earth's population) • October 2005 - Dead ducks test positive in Romania 6000 birds culled • Dead turkeys test positive in Turkey and Greece - 5000 birds culled. • A fresh outbreak in Mongolia - 2600 birds tested positive. • Dead swans in Croatia test positive. • October 31st - An H5 strain was found in Canada, still being tested to see if it is H5N1 Geographical Distribution Geographical Spread Geographical Spread Migratory Bird Patterns Geographical Spread Movie Time! Control of Spread • In 1997, the government of Hong Kong destroyed its entire poultry population, 1.5 million birds. • Hong Kong has banned sale of duck, geese, and quail • Instituted bimonthly cleaning days and vaccination of all locally raised and imported poultry • Thailand limiting poultry movement and destroying infected birds • China and Indonesia using poultry vaccines and Vietnam has started testing poultry vaccines Pandemic Nature • In 2002, acquired characteristics that allowed it to kill its natural host, the waterfowl • H5N1 expanded host range to tigers, leopards and domestic cats • Recent Finding in Pigs • Two components of pandemic strain: (1)New recombinant strain is formed (2) Easily transmissible amongst humans. Symptoms • Normal flu symptoms such as high fever, headache, extreme tiredness, dry cough, sore throat, runny or stuff nose, muscle aches, nausea, vomiting, diarrhea, and other stomach symptoms. • Eye infections, pneumonia, severe respiratory diseases such as acute respiratory distress, and other severe and life-threatening symptoms are also associated with avian flu. Treatment & Vaccines • Currently available Tamiflu® (oseltamavir) and Relenza® (zanamavir), developed resistance to Symmetral® (amantadine) and Flumadine® (rimantadine). • Vaccines available for poultry however no vaccine for human use • Countries working on developing a vaccine for H5N1 and H9N2 New Technology References • • • • • • • • • • • • • • • http://www.voanews.com/english/2005-09-30-voa63.cfm http://en.wikipedia.org/wiki/H5N1 http://www.reference.com/browse/wiki/Avian_influenza http://www.nlm.nih.gov/medlineplus/birdflu.html http://www.cdc.gov/flu/avian/ http://pandemicflu.gov/news/press.html http://www.cnn.com/interactive/world/0511/ap.migratory.patterns/frameset.e xclude.html http://www.nigms.nih.gov/News/Results/08032005.htm http://www3.niaid.nih.gov/news/newsreleases/2005/H5N1QandA.htm http://www.who.int/csr/disease/influenza/pandemic/en/index.html http://www.vnn.vn/dataimages/original/images112355_flucoding.jpg http://www3.niaid.nih.gov/news/focuson/flu/research/prevention/kawaoka_re versegenetics.htm http://www.scidev.net/News/index.cfm?fuseaction=readNews&itemid=1627& language=1 http://www.upc-online.org/spring04/images/image598412x.jpg Nature: Vol 435|26 May 2005 Questions?