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 further divided into subtypes based on their hemaglutinin (H) and neuraminidases (N). … A ssRNA enveloped virus
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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).
… A ssRNA enveloped virus
with 8 pieces (genes)
… 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
Influenza virus structure
Influenza changes 1. by antigenic drift of HA and NA,2. by cleavage of the HA,3. by HA changing to bind to different receptorsand, further by “shift” through Genetic Reassortment
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.
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
Duck or Chicken
of Influenza virus
gene segments arises
in a pig
Mixed infection of a pig
Many H5N1-infected chickens
Few H5N1-infected humans
No human-to-human transmission
Many H5N1-infected chickens
Many H5N1-infected humans
Moderately efficient human-to-human
Elements of a pandemic: Many H5N1-infected humans
Good human-to-human 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.
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.