Swine flu

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Swine flu
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Etiology

• influenza virus is an orthomyxovirus.
• This type of virus is divided into three groups
  type A, type B or type C.
• Type A viruses are further divided into subtypes
  based on their hemaglutinin (H) and
  neuraminidases (N).

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Influenza virus structure
A ssRNA enveloped virus with 8 pieces (genes)
of RNA With 2 surface glycoprotein Spikes
H and N And hemispheric clades of 15 H genes,
9 N genes E.g. H5N1 Bird flu . U.S. orders
200 million in H5N1 bird flu vaccine
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Influenza changes 1. by antigenic drift of HA
and NA,2. by cleavage of the HA,3. by HA
changing to bind to different
receptors and, further by shift through
Genetic Reassortment
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Swine Flu and Virus

• Swine Influenza (swine flu) is a respiratory
  disease of pigs caused by type A influenza virus
  that regularly causes outbreaks of influenza in
  pigs. Swine flu viruses cause high levels of
  illness and low death rates in pigs. Swine
  influenza viruses may circulate among swine
  throughout the year, but most outbreaks occur
  during the late fall and winter months similar to
  outbreaks in humans. The classical swine flu
  virus (an influenza type A H1N1 virus) was first
  isolated from a pig in 1930.

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Swine Flu differs from Human Flu

• At this time, there are four main influenza type
  A virus subtypes that have been isolated in pigs
  H1N1, H1N2, H3N2, and H3N1. However, most of the
  recently isolated influenza viruses from pigs
  have been H1N1 viruses. The H1N1 swine flu
  viruses are antigenically very different from
  human H1N1 viruses and, therefore, vaccines for
  human seasonal flu would not provide protection
  from H1N1 swine flu viruses

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• Why Pigs?
• 1-Ducks and pigs are raised by humans in close
  proximity.
• 2-Pig cells have virus receptors (virus binding
  capability) for both avian and mammalian
  influenza strains

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Influenza Reassortment
New Strain
Domestic Duck or Chicken
New Reassortment of Influenza virus gene
segments arises in a pig
Mixed infection of a pig
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Many H5N1-infected chickens
Few H5N1-infected humans No human-to-human
transmission
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Many H5N1-infected chickens
Reassort genes
Many H5N1-infected humans Moderately efficient
human-to-human
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Elements of a pandemic Many H5N1-infected
humans Good human-to-human transmission
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Stable Species Jumps or Evolutionary
Transmissions
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Stable Species Jumps or Evolutionary
Transmissions
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MAP of H1 N1 Swine Flu
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Summary
Year U.S. Deaths pop Global deaths global pop
1918 660,000 0.60 20-40 M 1.3-2.5
1957 70,000 0.04
1968 34,000 0.02
Next low estimate 102,086 0.04 2.0 M 0.03
Next high estimate 315,200 0.11 7.4 M 0.12
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Transmission

• Swine flu is contagious and is spreading from
  human to human. However, at this time, it is not
  known how easily the virus spreads between
  people.
• Swine flu is thought to be spread from person to
  person in the same way seasonal influenza and
  other common respiratory infections spread.
• Being in close contact (eg. within a metre) with
  an infected person while they are talking,
  coughing or sneezing puts
• you at risk of becoming infected.
  Virus-containing droplets can land on the
  surfaces of the mouth, nose and throat of people
  close by. The virus may also be spread through
  contact with infectious respiratory secretions on
  the hands of an infected person or other objects
  and surfaces.

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How long can viruses live outside the body?

• We know that some viruses and bacteria can live 2
  hours or longer on surfaces like cafeteria
  tables, doorknobs, and desks. Frequent hand
  washing will help you reduce the chance of
  getting contamination from these common surfaces.

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Infectious Period

• People with swine influenza virus infection
  should be considered potentially contagious as
  long as they are symptomatic and possibly for up
  to 7 days following illness onset. Children,
  especially younger children, might potentially be
  contagious for longer periods.

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How Swine Flu presents in Humans

• The symptoms of swine flu in people are expected
  to be similar to the symptoms of regular human
  seasonal influenza and include fever, lethargy,
  lack of appetite and coughing. Some people with
  swine flu also have reported runny nose, sore
  throat, nausea, vomiting and diarrhea

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Seek emergency medical care.IF - in Children

• In children emergency warning signs that need
  urgent medical attention include
• Fast breathing or trouble breathing Bluish skin
  color.Not drinking enough fluids
• Not waking up or not interacting
• Being so irritable that the child does not want
  to be held
• Flu-like symptoms improve but then return with
  fever and worse cough
• Fever with a rash

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Diagnosis

• To diagnose swine influenza A infection, a
  respiratory specimen would generally need to be
  collected within the first 4 to 5 days of illness
  (when an infected person is most likely to be
  shedding virus). However, some persons,
  especially children, may shed virus for 10 days
  or longer. Identification as a swine flu
  influenza A virus

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No Vaccines to HumansBut available to PIGS

• Vaccines are available to be given to pigs to
  prevent swine influenza. There is no vaccine to
  protect humans from swine flu. The seasonal
  influenza vaccine will likely help provide
  partial protection against swine H3N2, but not
  swine H1N1 viruses.

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Drugs which are effective in Swine Flu

• There are four different antiviral drugs that are
  licensed for use in the US for the treatment of
  influenza Amantidine, rimantadine, oseltamivir
  and zanamivir. While most swine influenza viruses
  have been susceptible to all four drugs

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• Thanks