This document discusses avian influenza viruses and their role in inter-species transmission. It notes that influenza A viruses can infect multiple species including humans, birds, pigs, and other animals. These viruses are classified into subtypes based on their surface glycoproteins HA and NA. The virus is transmitted through contact with infected bird secretions or contaminated surfaces. It also discusses how low pathogenic avian influenza viruses can mutate into highly pathogenic forms, and how pigs may serve as an intermediate host for genetic reassortment between avian and human viruses, increasing pandemic potential in humans.

1. Avian Influenza Viruses and its
role in inter-species Transmission
Rokshana Parvin and T.W. Vahlenkamp
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2. Influenza virus
Influenza viruses causes highly contagious respiratory
disease with potentially fatal outcomes.
Family: Orthomyxoviridae
Three main types
 Type A
Multiple species
 Type B
Humans
 Type C
Humans and swine
http://www.uct.ac.za/depts/mmi/stannard/fluvirus.html
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3. Influenza virus genome
The influenza A genome consists of eight single-stranded negative-
sense RNA molecules encoded 10 proteins within viral envelope
HA - hemagglutinin
NA - neuraminidase HA
NA
M
helical nucleocapsid (RNA plus NS
NP protein) NP
PA
lipid bilayer membrane PB1
PB2
polymerase complex
M1 protein
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4. Influenza virus Type A
 Influenza A viruses are further classified into subtypes based on the
antigenicity of their surface glycoproteins (HA & NA )
Hemagglutinin (HA) Neuraminidase (NA)
H1, H2, H3, H4, H5, H6, H7, H8, N1, N2, N3, N4, N5, N6, N7, N8,
H9, H10, H11, H12, H13, H14, N9
H15, H16
So far at least 84 serotypes (HA &NA combination) are found in
resivour
 Infect multiple species
Humans
Birds (wild birds, domestic poultry)
Other animals: pigs, horses, dogs, marine mammals (seals,
whales)
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5. H5
H5, H7, H9
H3, H7
HA 1-16
NA 1-9
H4, H7, H13
H1 - H3 H1 - H3 H3, H7
H5, H7, H9 H5
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6. How they transmitted ??????????????
The virus is contracted through
 Contact with saliva, nasal secretions and feces of the wild birds.
 Contaminated surfaces or materials.
 Contaminated water
* Direct or indirect contact
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7. True influenza
influenza virus A or influenza virus B
Febrile respiratory disease with systemic symptoms
caused by a variety of other organisms often called „flu‟
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8. Influenza descriptions
Influenza name Strain Host affected Outbreak year
Seasonal Flu H3, H1 humans yearly
Spanish Flu H1N1 humans 1918
Asian Flu H2N2 humans 1957
Hong Kong Flu H3N2 humans 1968, 1970-72
bird flu H5N1 Poultry, 1997,
(endemic in 2003………..
avian), human,
& cat
Swine flu H1N1 Humans, swine 2009
* H1N2 is currently endemic in humans and pigs
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9. Bird Flu:
H5N1, H7N7,H9N2…
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10. HPAI LPAI
H5, H7 H9, H7
H5N1 H9N2
Highly pathogenic viruses result in high Low pathogenicity viruses also cause
death rates (up to 100% mortality within outbreaks in poultry but are not
48 hours) in some poultry species generally associated with severe clinical
disease
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11. transmitted to poultry
LPAI virus circulates in
Natural reservoir of
poultry with mild disease
LPAI (H9, H5, H7) virus
LPAI Virus Mutates to
HPAI with severe disease
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13. • The current outbreaks of highly pathogenic avian
influenza, which began in South-East Asia in mid-2003,
are the largest and most severe on record
• Never before in the history of this disease have so many
countries been simultaneously affected, resulting in the
loss of so many birds
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14. Outbreaks map of HPAI H5N1 in
poultry (2003 – March 2012)
≥ 100 outbreaks
≥ 10 outbreaks
≥ 1 outbreaks
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15. Bird flu: Why is there a risk for humans?
Role of pigs as an intermediate host
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16. Differences between Pandemics and
Epidemics
 Pandemics are different from seasonal outbreaks or
“epidemics” of influenza
 Seasonal outbreaks are caused by subtypes of influenza
viruses that are already in existence among people
 Pandemic outbreaks are caused by new subtypes or by
subtypes that have never circulated among people or
that have not circulated among people for a long time
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17. Seasonal Epidemics vs. Pandemics
Seasonal Influenza Influenza Pandemics
– A public health problem – Appear in the human
each year population rarely and
unpredictably
– Usually some immunity
built up from previous – Human population lacks
exposures to the same any immunity
subtype
– Infants and elderly most – All age groups, including
at risk healthy young adults
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18. If a new subtype of influenza A virus is introduced into
the human population, most people have little or no
protection against the new virus, and if the virus can
spread easily from person to person, a PANDEMIC
(worldwide spread) may occur
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19. Prerequisites for pandemic influenza
A new influenza virus emerges to which
the general population has little/no
immunity
The new virus must be able to replicate
in humans and cause disease
The new virus must be efficiently
transmitted from one human to another
Ingredients for a pandemic are abundantly available
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20. Influenza A viruses are renowned for their rapid
evolution in aberrant hosts including humans
Antigenic drift occurs when single Antigenic shift takes place when two
nucleotides are replaced over time different viruses infect the same cell and
through mutations new viral particles are created with new
combinations or assortments of the 8
influenza molecules
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22. Antigenic
shift
Sick Pig with both Strands of Influenza
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23. 1st pandemics of 21th century
Pandemic Year Influenza virus People infected Estimated deaths
type worldwide
Swine flu 2009– Pandemic > 622,482 (lab- 14,286 (lab-confirmed;
2010 H1N1 confirmed) ECDC
18,036 (lab-
confirmed;WHO)
The pandemic that began in March 2009 was caused by an H1N1
influenza A virus that represents a quadruple reassortment of two swine
strains, one human strain, and one avian strain of influenza; the largest
proportion of genes came from swine influenza viruses.
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24. History of Reassortment Events in the
Evolution of Influenza A H1N1/09
H1N1/ 09
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26. 20th century flu pandemics
Spanish flu Asian flu Hong Kong Flu
Emergency military hospital Children's ward during Hong Kong Flu Pandemic
during Spanish flu pandemic Asian flu pandemic (1968,1970-1972)
(1918) (1957)
A(H1N1) A(H2N2) A(H3N2)
20-40 m deaths 1-4 m deaths 1-4 m deaths
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28. Now literature says…
Bird flu can transmitted directly from birds to humans
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29. Possible mechanisms for the generation of
pandemic influenza viruses
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30. Current situation
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33. http://www.who.int/csr/don/2012_04_12/en/index.html
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34. http://www.oie.int/fileadmin/Home/eng/Animal_Health_in_the_World/docs/pdf/gr
aph_avian_influenza/graphs_HPAI_31_03_2012.pdf
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36. http://www.fao.org/ag/againfo/programmes/en/empres/maps_cum_archive.html
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37. Next warning
?
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39. For your kind attention!!!!
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