1. بسم الله الرحمن الرحيم

2. AVIAN INFLUENZA Prof. Dr. SALAH M. HASSAN College Vet. Medicine
Mosul University

3. CLASSIFICATION Family: Orthomyxoviridae
Influenzavirus A
humans
horses
pigs
birds
marine mammals
Influenzavirus B
Influenzavirus C
swine

4. Avian influenza (AI) asymptomatic infection to respiratory disease
and drops in egg production to
severe, systemic disease with near 100% mortality

5. Etiology Orthomyxoviridae, genus Influenzavirus A single-stranded RNA
surface is covered by two types glycoprotein projections (HA), (NA).

6. Type A Influenza Orthomyxovirus Negative sense RNA Single stranded
Segmented
Enveloped
16 H
9 N

7. Influenza Subtypes 16 Hemagglutinin subtypes 9 Neuraminidase subtypes
144 possible antigenic subtypes

8. cause HPAI in susceptible
Avian Influenza
Only viruses of
H5 and H7 subtypes
have been shown to
cause HPAI in susceptible
species

9. Avian Influenza
HPAI emerges from LPAI

10. Avian Influenza
Not all H5 and H7
viruses are HPAI

11. Susceptibility to Chemical and Physical Agents
Unstable in the environment.
Physical factors such as
heat
extremes of pH
dryness

12. Reassortment (antigenic shift)
Major Antigen
AI Virion
RNA Segments

13. ‘Classical’ Model for Cross Species Spread of Flu
Reassortment in swine ? ?
Virus with new host specificity ?

14. In Waterfowl, Influenza Viruses Replicate preferentially in the
Intestinal tract. Virus transmission
Among aquatic birds is via
Contaminated water-oral
Route.

15. Of Influenza A Virus are (Ducks, Shorebirds and gulls)
Transmission and
Carriers
All 16 HA and 9 NA Subtypes
Of Influenza A Virus are
Maintained in aquatic
Bird populations
(Ducks, Shorebirds and gulls)

16. Major Outbreaks of Avian Influenza in Domestic Poultry Comments Impact
Location
Subtype
Year
A serologically identical but apparently mild virus had been circulating in poultry in the area for 6 mo (see References: Beard 1998). No human cases were identified.
Caused severe clinical disease and high mortality rates in chickens, turkeys, and guinea fowl.
17 million birds were culled.
Pennsylvania H5
1983
An LPAI virus mutated to an HPAI virus and caused an outbreak in The H5N2 strain has continued to circulate in Mexico since that time. No human cases have been identified.
Nearly a billion birds have been affected.
Mexico
H5N2
A vaccination campaign apparently ended the outbreak. No human cases were identified.
About 3.2 million birds died from avian influenza during initial outbreak in 1995.
Pakistan
H7N3
18 human cases with 6 deaths were recognized. Prior to this outbreak, H5N1 was not known to infect humans.
Virus was isolated from chickens; avian mortality rates were high. 1.5 million birds were culled in 3 days.
Hong Kong
H5N1
1997
Over 80 human cases were reported, and one veterinarian died (see References: Fouchier 2004, Stegeman 2004). Most of the human cases involved conjunctivitis.
30 million birds out of 100 million birds in country were killed; 255 flocks were infected. Disease spread to Belgium but was quite rapidly contained.
The Netherlands
H7N7
2003
More than 410 human cases have been recognized, with more than half of them fatal, in Azerbaijan, Bangladesh, Cambodia, China, Djibouti, Egypt, Indonesia, Iraq, Lao People's Democratic Republic, Myanmar, Nigeria, Pakistan, Thailand, Turkey, and Vietnam.
Panzootic avian influenza, with outbreaks occurring in many countries around the globe. By August 2006, an estimated 220 million birds had died or been culled (see References: FAO 2006: Caucasus, Balkans at high risk for deadly H5N1 virus).
Asia, Europe, Africa
(ongoing)
Two human cases were recognized; both patients had conjunctivitis.
Over 19 million birds were culled.
British Columbia
2004
No human cases were identified.
About 200,000 birds were culled.
North Korea H7
2005
aAdditional outbreaks of HPAI have been identified in a variety of countries.
Adapted from Capua 2004 (see References).

17. Countries Affected by H5N1 in Poultry and Wild Birds as of March 2009
Africa
Siberia, Central Asia, Middle East
Europe
East Asia, Southeast Asia
Benin Burkina Faso Cameroon Djibouti Egypt Ghana Ivory Coast Niger Nigeria Sudan Togo
Afghanistan Azerbaijan Bangladesh Cyprus Georgia India Iran Iraq Israel Jordan Kazakhstan Kuwait Nepal Pakistan Turkey Ukraine Russia (Siberia) Saudi Arabia West Bank and Gaza Strip
Albania Austria Bosnia-Herzegovina Bulgaria Croatia Czech Republic Denmark England France Germany Greece Hungary Italy Poland Romania Russia (European Russia) Scotland Serbia Slovakia Slovenia Spain Sweden Switzerland
Cambodia China Hong Kong Indonesia Japan Lao PDR Malaysia Myanmar Mongolia South Korea Thailand Vietnam

19. 2005

20. 2006

21. 2007

22. 2008

23. 2009

24. How is the disease transmitted and spread?
Several factors can contribute to the spread of AI viruses including globalization and international trade (legally and illegally), marketing practices (live bird markets), farming practices and the presence of the viruses in wild birds.

25. Mechanism for pathogenicity in poultry
Sequences in HP viruses can be cleaved in many tissue types resulting in systemic infection (arginin + lysine) cleavage by protease. HP

26. Mechanism for pathogenicity in poultry
Some sequences can only be cleaved by enzymes in the respiratory tract or intestinal tract arginin.( trypsin like enzymes) LP LP

27. Incubation Period 3 up to 14 days dose of virus route of exposure
species exposed
ability to detect clinical signs

28. Morbidity and Mortality
LP AI less than 5% unless
HP AI 50—89% and can reach 100%

29. Properties of virulent and avirulent AI
Property
Avirulent strains
Virulent strains
HA subtype
H1-H16
H5, H7
Replication
Respiratory and/or intestinal tracts
Most organs.
Disease
Inapparent or mild Respiratory signs)
systemic or "fowl plague" symptoms
Mortality
Low
High (up to 100%)
Plaque formation in cell culture without exogenous protease No
Yes
HA cleavage by intracellular proteases
HA cleavage site sequence
Single
Multiple basic amino acids

39. Sinusitis
Sinusitis

40. Tracheitis

48. Hemorrhagic- necrotic Pancreatitis

51. Gross lesions

52. In layers and breeders, reduce egg production

53. (First) Diagnosis of AIV
- isolation of hemagglutinating agent in
embryonated eggs; daily candling of eggs
- determine H-subtype by HI-ab
- determine virulence with IVPI
- sequencing cleavage site hemagglutinin: (Note mixtures of LP and HP)

65. Thank you