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Influenza A Zoonosis

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Influenza A Zoonosis. Saad Gharaibeh BVM, PhD, Dip ACPV. Dept. of Pathology and Animal Health ... Dr. Gary Butcher specializing in avian diseases, and has a Ph. ... – PowerPoint PPT presentation

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Title: Influenza A Zoonosis


1
Influenza A Zoonosis
  • Saad Gharaibeh BVM, PhD, Dip ACPV
  • Dept. of Pathology and Animal Health
  • Faculty of Veterinary Medicine
  • Jordan University of Science and Technology
  • Irbid 22110, Jordan

2
NI test
HI test
AGP test
ELISA test
Jong et al., 2000, Journal of Infection
3
Dr. Gary Butcher specializing in avian diseases,
and has a Ph.D. in poultry virology.
  • "The threat is basically zero,
  • "We're spending all of our attention on this
    virus, and another one may sneak up on us."

4
http//news.bbc.co.uk/2/hi/americas/8021547.stm
5
Influenza History
  • Avian influenza was first described in 1878 as
    fowl plaque disease in Italy. The causative agent
    was isolated in 1902 (A/chicken/Brescia/1902
    H7N7). By 1955, it was characterized as
    influenza virus.
  • In 1930, influenza virus, A/swine/Iowa/30, was
    isolated.
  • In 1933, the first human virus was isolated in
    London, England.

6
Previous Influenza Pandemics
  • Spanish flu (1918-1919) H1N1
  • Asian flu (1957) H2N2
  • Hong Kong flu (1968) H3N2
  • Russian flu (1977) H1N1

7
http//en.wikipedia.org/wiki/Swine_influenza
8
Fields virology, 3rd ed
9
(No Transcript)
10
Pig Involvement
  • A number of findings have suggested a role for
    pigs in the emergence of pandemic influenza
    viruses
  • Pigs can be naturally or experimentally infected
    with avian viruses.
  • Epithelial cells in pig trachea contain both
    human- and avian-type receptors
  • In nature, continued replication of an avian
    virus in pigs leads to variants that
    preferentially recognize human-type receptors
  • Swine viruses and avian-human reassortant viruses
    can infect humans and, in some cases, cause fatal
    disease
  • Interspecies transfer and reassortment events
    have led to the establishment of two new lineages
    of pig viruses since 1979, demonstrating that
    pigs can host genetically diverse viruses

11
Pig Involvement
  • Swine influenza is enzootic in pigs and is the
    most prevalent respiratory disease in these
    animals
  • in 1918 and 1919, pigs presented with symptoms
    similar to those observed in humans, that is,
    nasal discharge, coughing, fever, labored
    breathing, and conjunctivitis.
  • Phylogenetic analyses indicated that the
    1918/1919 human and swine viruses were
    genetically similar and likely originated from a
    common ancestor.

12
Main Influenza Groups in Pigs
  • Classical swine viruses H1N1 (1918-1976) America
    and Europe
  • Avian-like H1N1 (after 1979) America and Europe
  • Human-like viruses H3N2 after 1970 in Taiwan.
  • Reassortant Viruses H1N2 viruses (after 1978 in
    Japan) that resulted from reassortment of
    classical H1N1 swine viruses and human H3N2
    viruses
  • H3N2 triple human/avian/swine reassortant viruses
    emerged in North America (1998)

13
Fields virology, 5th ed
14
Swine-Human Virus Exchange
  • 1938, serologic evidence for the transmission of
    a human virus to pigs.
  • 1976, an H1N1 swine virus was isolated from a
    soldier who had died of influenza at New Jersey.
    This virus was subsequently isolated from five
    other soldiers, and serologic studies suggest
    that more than 500 personnel were infected.
  • Numerous other reports have described the
    transmission of swine viruses to humans, and
    transmission of human viruses to pigs.
  • Avian H9N2 and H5N1 viruses have from Southeast
    Asia.

15
Done and Brown, 1999
16
Pathogenesis in Pigs
  • Morbidity may be up to 100
  • Mortality rate is low and recovery is rapid
  • Secondary bacterial infections can increase the
    severity of illness and may result in
    complications such as pneumonia.
  • Once a herd is infected, the virus is likely to
    persist through the production of young
    susceptible pigs and the introduction of new
    stock.
  • Outbreaks of disease occur throughout the year
    but usually peak in the colder months.

17
Pathogenesis in Pigs
  • Infection is often subclinical and typical signs
    are seen in only 25 to 30 of a herd.
  • Disease transmission is primarily direct and
    occurs via the nasopharyngeal route through the
    dispersal of aerosols.
  • Nasal secretions are laden with virus during the
    acute febrile stages of infection and virus
    excretion lasts for approximately 6 days.
  • The severity of clinical disease is influenced by
    many factors but most importantly by
  • maternal immunity
  • virus strain
  • route of inoculation
  • secondary bacterial infections.

18
Clinical Signs in Pigs
  • Influenza is an acute febrile, respiratory
    disease characterised by
  • Fever
  • Apathy
  • Anorexia
  • Laboured breathing
  • Coughing may be apparent during the later stages
    of disease
  • Clinical signs seen less frequently include
    sneezing, nasal discharge and conjunctivitis.

19
Pathological Lesions
  • Typical viral pneumonia (interstitial)
  • Most often limited to the apical and cardiac
    lobes of the lungs, although in severe cases more
    than half of the lung may be affected.
  • The altered lung areas are depressed and
    consolidated and are dark red or purple-red in
    color, contrasting sharply with normal tissue.
  • The airways are likely to be dilated and filled
    with blood-tinged, fibrinous exudate.
  • The associated bronchial and mediastinal lymph
    nodes are usually enlarged.

20
Histopathological Lesions
  • Microscopic lesions usually consist of airways
    filled with exudate.
  • Widespread alveolar atelectasis, interstitial
    pneumonia and emphysema.
  • Peribronchial and perivascular cellular
    infiltration is also seen.

21
Avian Influenza Infections in Humans
http//www.mayoclinicproceedings.com/
22
Public health
(Capua Alexander, 2005)
23
AI in Human
H5N1
24
Courtesy of Dr. Hafez
25
Thank You
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