Transcript Influenza Presentation by Virginia Dato at MMRS13 Nov 10,2005

The A,B,C’s of Influenza
Virginia Dato MD MPH
Public Health Physician
Bureau of Epidemiology
Pennsylvania Department of Health
A, B, C’s of Influenza


Influenza A - A should stand for Avian (Believed
to originate in wild birds now wide range of
viruses infect a wide range of species.)
– H subtypes [1-16 ]
– N subtypes [1-9]
Influenza B
– Just humans, some epidemics, no pandemics

Influenza C
– Mild illness no epidemics
2
The Enemy - Influenza A
Hemagglutinin
– Required for
attachment to the
host cell
membrane
polymerase (PB1)
RNA –
Subject to
lots of
random
errors.
PB2, PA
four amino acids
of PA, one of
PB1, and five of
PB2 that are
found in human
Neuramindase
– Required for
virus release
3
Antigenic drift (if a mutation allows
it to jump a species it is a shift)
4
SHIFT
5
6
7
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Where did it come from?
9
Geographically – Possible Haskell
County, Kansas,
“There the smell of manure meant
civilization. People raised grains,
poultry, cattle, and hogs. Sod-houses
were so common that even one of the
county's few post offices was located
in a dug-out sod home. In 1918 the
population was just 1,720, spread
over 578 square miles. “ from John
Barry
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Could a virus this nasty happen
again?
Natural recombination/resortment of genes
 Accidental or Intentional
recombination/resortment of genes
 Release from the past - Accidental release
from a laboratory storing the 1918 virus or
other pandemic strains which humans no
longer have immunity to.

11
http://www.cdc.gov/flu/weekly/weeklyarchives20082009/bigpi04.htm
12
Other significant Influenza
pandemics
1957-1958 “Asian Flu” H2N2 – 70,000 US
deaths
 1968-1969 “Hong Kong flu” H3N2- 34,000
US deaths (H3N2 viruses still circulating
today)

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The Two Mechanisms whereby Pandemic Influenza Originates
Belshe, R. B. N Engl J Med 2005;353:2209-2211
14
Belshe, R. B. N Engl J Med 2005;353:2209-2211
15
HPAI vs LPAI – a poultry definition

high pathogenic avian influenza (HPAI)
– HPAI viruses can cause severe illness and high
mortality in poultry.

low pathogenic avian influenza (LPAI)
– LPAI viruses are usually associated with mild
disease in poultry.

Human’s usually don’t get either if they do
tend to only get conjunctivitis from LPAI
16
SO not all H5N1 are the same
H5N1 in Ducks in Crawford County –
The ducks were sampled August 28, 2006 in
Crawford County, Pennsylvania. THIS is
NOT the HPAI H5N1 that we are worried
about.

17
http://www.pandemicflu.gov/ ( February, 13 2009)
18
http://www.cidrap.umn.edu/cidrap/content/influ
enza/avianflu/news/feb0609avian.html
"So far, despite a large number of samples from poultry being
collected and laboratory tested, no evidence of infection in
poultry has been found to explain these human cases," Martin
said.
19
http://www.fao.org/ag/againfo/subjects/en/health/dis
eases-cards/avian_hpairisk.html
20
http://www.fao.org/ag/againfo/progr
ammes/en/empres/Images/maps/200
9/hpai_05jan_05feb_09.gif
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What about canine influenza?
H3N8
 Known to circulate in horses for 40 years.
 Probably jumped from a single horse to a
single greyhound. Evidence that it has been
in greyhounds at least as early as 2000 (or
earlier).
 First caught attention in deadly outbreaks
2004 in Florida racing greyhounds.

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Human Implications of Canine
Influenza




Morbidity and mortality for our pet and service
dogs.
No known human cases (which is why we are not
as worried about this as H5N1)
Recombination (shift) with another influenza A
theoretically possible if the same organism is
infected with H3N8 and another strain at the same
time (H5N1 ???)
H3N8 vaccination when available for dogs will
significantly decrease that chance.
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What about Swine Influenza?
The CDC typically receives about one report of a human
swine flu case a year, the SDDH statement said. In late
November the CDC, in one of its seasonal influenza activity
updates, reported on a patient from Texas who was infected
with swine influenza after exposure to pigs, including a sick
one.
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How does avian influenza
(H5N1) spread? (as of
4/04/2007)

Bird to Bird - very easy
– Through feces and other secretions
– Facilitated by crowded conditions and mixing of birds in bird
markets.

Bird to Mammal (human, cat,dog)
– Through eating uncooked bird
– Through extremely close contact (sleeping with birds in same
small area.)

Mammal to Mammal
– Very rare human to human associated with extremely close
intimate contact. No known cat to human.
– Will the virus mutate to make spread easier???????
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How will Pandemic Influenza
Spread?
 Droplet
like seasonal influenza?
 Direct or Indirect contact like seasonal
influenza?
 Feces and other secretions like avian
influenza?
 Airborne like measles?
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Seasonal Influenza Spreads Via
Droplet Transmission
Courtesy of Centers for Disease Control and Prevention
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Direct exposure to droplets

Direct mucous membrane (eyes, mouth, nose) exposure to
flu virus. Since droplets fall out of the air quickly this
usually happens if you are in the path of a cough, sneeze or
breath..
Stay out of the droplet zone
Courtesy of Centers for Disease
Control and Prevention
The Droplet zone
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Seasonal Influenza spreads via
Indirect Exposure

Indirect contact via your hands or
something else picking up virus and getting
it onto your mouth, eyes or nose.
Courtesy of
Centers for
Disease
Control
and
Prevention
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Airborne Transmission
Tiny Infectious droplet nuclei less than 5
microns.
 The small virus particles hang in the air –
sometimes for hours. Important for
smallpox, measles, chicken pox.
 Less important for SARS and most
Influenza (but if you are trying to contain a
rare or highly fatal disease every little bit
counts.)

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Foodborne or Fecal-Oral
Transmission?





Existing commercial precautions already excellent
Restaurants have hand washing sinks in kitchens
Poultry and eggs already need to be well cooked
No bare hand contact with ready to eat food
already in place.
Good agriculture practices related to produce
being put in place
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Vaccination – The Best Defense


Vaccination is the best defense because it prepares
the immune system to rapidly respond when
exposed to the virus.
This rest of this lecture is for when a person can’t
get a vaccine because:
– an effective safe vaccine does not exist or there are
shortages
– the person has a medical reason that keeps him/her from
getting vaccinated.
– The person has an immune deficiency that makes the
vaccine less effective.
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Anti- viral/anti-microbial agents are
nice but…
Can there be an adequate supply?
 Will the agents develop resistance?
 Can people afford them?

Single drug agent resistance is
currently widespread.
33
Results as of 2/13 Nationwide
H1N1 190 tested 185 (97.4%) resistant to Oseltamivir, 2
(1.1% resistant to the Adamantanes)
H3N2 41 tested 0 resistant to oseltamivr, 41 (100% resistant to
the adamantanes)
Influenza B – The adamantanes have never had activity against B
No known zanamivir resistance,
No known double resistance – yet
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NON-Pharmaceutical Interventions
Things people can do to keep from getting
and giving infections.
 Policy’s institutions can make to decrease
infections
 Engineering changes institutions can make
to decrease infections.

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Individuals can decrease
personal exposure
Keep hands clean
 Stay out or get out of the air space of the
infectious or potentially infectious – wear a
protective mask if you can’t
 Limit intimate contacts (human, animal, avian,
infectious surface)
 Don’t share (toothbrushes, glasses, towels,
etc.)
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 Watch what you eat or drink

What about Masks?

Basic surgical masks for the person who is
sick.
– These masks catch the droplets of virus even if
the person is not fast enough to cover their
cough themselves. In Japan many people wear
masks to work when they have a cold as a
curtsey to those around them. (Can’t find one
to buy – making one probably works too. – 2
ply T-shirt material tested by the military)
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For the individual who is well
– Surgical mask will keep you from getting
droplets directly on your face and nose, but not
your eyes (consider glasses) if you are in the
droplet zone and get a direct hit.
– Surgical masks will NOT keep you from
breathing in droplets so move back if you are
in the droplet zone. Or make sure you get a
mask that filters all of the air you breath. (Fit is
most important. When you breath in you pull
air around a typically fitting surgical mask. )
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Examples of Institutional Policy
Changes
Make sure that supplies are in place to help
stop the spread of respiratory infections
(tissues, hand sanitizer, soap)
 Educate employees about disease
transmission.
 Liberal tele-commuting/ sick leave policies
 Extend hours.

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Institutional Engineering Changes
Increase building air exchanges
 Air filtration systems
 Air flow away from potentially sick
individuals
 Clear plastic or other barriers that separate
individuals
 Spread desks to increase spacing between
individuals

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Stay informed; be prepared to
change.

Multiple websites are available with the
latest information including
– http://www.pandemicflu.gov
– www.cdc.gov
– http://www.pandemicflu.state.pa.us/
– www.promedmail.org
– http://www.cidrap.umn.edu/
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