Title: Influenza A Zoonosis
1Influenza 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
2NI test
HI test
AGP test
ELISA test
Jong et al., 2000, Journal of Infection
3Dr. 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."
4http//news.bbc.co.uk/2/hi/americas/8021547.stm
5Influenza 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.
6Previous Influenza Pandemics
- Spanish flu (1918-1919) H1N1
- Asian flu (1957) H2N2
- Hong Kong flu (1968) H3N2
- Russian flu (1977) H1N1
7http//en.wikipedia.org/wiki/Swine_influenza
8Fields virology, 3rd ed
9(No Transcript)
10Pig 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
11Pig 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.
12Main 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)
13Fields virology, 5th ed
14Swine-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.
15Done and Brown, 1999
16Pathogenesis 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.
17Pathogenesis 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.
18Clinical 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.
19Pathological 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.
20Histopathological 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.
21Avian Influenza Infections in Humans
http//www.mayoclinicproceedings.com/
22Public health
(Capua Alexander, 2005)
23AI in Human
H5N1
24Courtesy of Dr. Hafez
25Thank You