The A,B,C

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The A,B,Cs of Influenza

• Virginia Dato MD MPH
• Public Health Physician
• Bureau of Epidemiology Pennsylvania Department of
  Health

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A, B, Cs 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

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The Enemy - Influenza A
RNA Subject to lots of random errors.
Hemagglutinin Required for attachment to the
host cell membrane
polymerase (PB1) PB2, PA
Neuramindase Required for virus release
four amino acids of PA, one of PB1, and five of
PB2 that are found in human
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Antigenic drift (if a mutation allows it to jump
a species it is a shift)
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SHIFT
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Where did it come from?
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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.

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http//www.cdc.gov/flu/weekly/weeklyarchives2008-2
009/bigpi04.htm
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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 20053532209-2211
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Belshe, R. B. N Engl J Med 20053532209-2211
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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.
• Humans usually dont get either if they do tend
  to only get conjunctivitis from LPAI

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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.

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 http//www.pandemicflu.gov/ ( February, 13
2009)
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http//www.cidrap.umn.edu/cidrap/content/influenza
/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.
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http//www.fao.org/ag/againfo/subjects/en/health/d
iseases-cards/avian_hpairisk.html
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http//www.fao.org/ag/againfo/programmes/en/empres
/Images/maps/2009/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
  cant 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.
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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.
• Policys 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 cant
• Limit intimate contacts (human, animal, avian,
  infectious surface)
• Dont share (toothbrushes, glasses, towels, etc.)
• Watch what you eat or drink

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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. (Cant 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/