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
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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
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