Transcript Avian Influenza

Avian Influenza:
A Zoonotic Disease of International
Importance
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WHAT IS INFLUENZA?
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What is influenza?
• Influenza (or the flu) is a disease caused by a
VIRUS
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What are the symptoms of influenza?
Once people are infected with an influenza virus, they can
develop the following symptoms:
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Fever
Cough
Sore throat
Stuffy nose
Body aches
Headaches
Fatigue (very tired)
Some people may have vomiting and diarrhea, although this is
more common in children than adults.
Vaccinations are available to help prevent you from being infected
with influenza.
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What is a virus?
• What is a virus?
– An infectious
agent that can
replicate only
INSIDE a HOST
CELL
What are the names of some
common viruses?
•Rabies virus
•Influenza virus
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How big is a virus?
• If a human cell were the size of the SUN, a
virus would be about the size of the EARTH!
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What does a virus look like?
RABIES
POLIO
Common cold
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What does a virus look like?
Attachment Molecules
Protein coat
Genetic Material
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SPREAD OF INFLUENZA
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Seasonal epidemic influenza
• An epidemic occurs when substantially more
cases of a disease (such as the flu) occur in a
place during a certain time period than
would normally be expected.
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Pandemic influenza
• A pandemic is an epidemic of infectious
disease (such as influenza) that affects
populations across a large region.
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How is influenza spread?
• Influenza spreads easily from person to
person through coughing and sneezing.
• Influenza is also spread by touching an
infected person or an item contaminated
with the virus and then touching your eyes,
nose, or mouth.
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Why you should cover your mouth
when you sneeze!
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Some influenzas are more
dangerous than others!
Versus
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Influenza viruses
Influenza viruses are of three main types:
– A viruses
• Infect birds and other animals as well as humans
• Are a source of seasonal influenza epidemics and all pandemics
– B viruses
• Infect humans only and do not cause pandemics (can cause
epidemics, but generally less severe than “A”)
– C viruses
• Infect humans and swine (pigs) and do not cause pandemics
• Usually cause only mild disease
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HISTORICAL OUTBREAKS
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1918—Spanish flu
 This outbreak caused 20-40 million deaths worldwide.
– 675,000 Americans died during this outbreak.
– 43,000 U.S. soldiers died during this outbreak.
 During World War I, this outbreak was called the Spanish flu
mainly because the pandemic received more attention in the
news after it moved from France to Spain in November 1918.
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1918—Spanish flu
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Other influenza pandemics
• 1957- Asian flu
– 1 million deaths worldwide
– Approximately 70,000 U.S. deaths
• 1968- Hong Kong flu
– 1 million deaths worldwide
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AVIAN INFLUENZA
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Avian influenza
• “Avian influenza”
– Means influenza A viruses that occur naturally in
wild water birds
– Can spread to people and other types of animals
Bar-headed Geese
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Why are some influenzas more
severe than others?
Avian influenza viruses are classified by surface
molecules on the virus.
◦ Hemagglutinin (H)
 H1-H16
 Sites for attachment to infect cells of the host (for
example, bird or person)
◦ Neuraminidase (N)
 N1-N9
 Assists in the release of newly formed virus particles from
the surface of an infected cell
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Why are some influenzas worse than
others?
• Viruses with certain combinations of “H” and “N”
cause more severe disease in both people and
poultry (for example, chickens).
• These viruses are called highly pathogenic avian
influenza (HPAI) viruses
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Avian influenza (H5N1)
• A highly pathogenic avian influenza virus (H5N1) first
showed up in Hong Kong in 1997. This virus is now
circulating in birds in many countries in Asia and the
Middle East.
• This influenza virus is very dangerous to domestic
poultry (for example, chickens). This virus and can also
make people very sick.
• So far, the virus doesn’t spread very easily from person
to person. However, people can become sick after
contacting an infected bird.
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Avian influenza (H5N1)
• What do you
think would
happen if one of
these chicks got
sick with H5N1
avian influenza?
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Avian influenza (H5N1)
How is H5N1 avian
influenza spread
from birds to
humans?
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Spread of H5N1 avian influenza
• H5N1 avian
influenza can
be spread by
inhaling dried
bird droppings.
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Spread of H5N1 avian influenza
• H5N1 avian influenza can spread through the
butchering process and handling of infected birds.
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Spread of H5N1 avian influenza
• Remember that H5N1 avian influenza DOES NOT
spread easily between humans like the seasonal flu.
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How do you stop the spread of H5N1
avian influenza?
• One solution is to get
rid of all of the
poultry (for example,
chickens) that might
be infected.
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How do you stop the spread of H5N1
avian influenza?
• We can also stop the
spread of H1N1 avian
influenza by providing
protection for poultry
workers, including:
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Mask
Gloves
Eye shield
Disposable suit
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Why is H5N1 avian influenza important?
• The danger is that avian influenza viruses change
very frequently.
– Humans can’t transmit the current H1N1 avian influenza
between themselves very well.
– However, the virus could change into a form that could be
transmitted between people.
– If this happened, the virus could cause a global pandemic
with lots of people becoming sick.
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Do we have H5N1 avian influenza in
the USA?
• No, we currently don’t have H5N1 avian influenza in
the USA.
• However, in the USA some influenzas with other “H”
and “N” combinations have killed poultry and
severely affected people.
• The US government is very careful about monitoring
influenza viruses and quickly making efforts to
eliminate dangerous virus forms.
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Conclusions
• Influenza viruses cause the flu.
• Influenza viruses are spread from person to person
by coughing and sneezing.
• Avian influenza viruses occur naturally in birds, but
can sometimes be transmitted to humans and other
animals.
• Highly pathogenic avian influenza viruses can be
very dangerous to poultry and humans.
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