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Swine flu

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Swine flu 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 ... – PowerPoint PPT presentation

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Title: Swine flu


1
Swine flu
2
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).

3
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
4
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
5
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.

6
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

7
  • 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

8
Influenza Reassortment
New Strain
Domestic Duck or Chicken
New Reassortment of Influenza virus gene
segments arises in a pig
Mixed infection of a pig
9
Many H5N1-infected chickens
Few H5N1-infected humans No human-to-human
transmission
10
Many H5N1-infected chickens
Reassort genes
Many H5N1-infected humans Moderately efficient
human-to-human
11
Elements of a pandemic Many H5N1-infected
humans Good human-to-human transmission
12
Stable Species Jumps or Evolutionary
Transmissions
13
Stable Species Jumps or Evolutionary
Transmissions
14
MAP of H1 N1 Swine Flu
15
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
16
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.

17
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.

18
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.

19
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

20
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

21
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

22
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.

23
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

24
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