1. Avian Influenza Poultry Pathology
Dr. Latif Ahmad,
Assistant Professor,
BCVS-BMU-Karachi

2. Avian influenza is caused by ortyhomyxoviruses. Several serotypes.
Contagious viral inf. and/or disease of many avian species including poultry, wild & exotic birds, ratites, shore birds & migratory waterfowl.
The highly pathogenic form of the disease is characterized by severe depression, decrease in egg prod., high mortality, edema, hem. & frank necrosis.
All H5 & H7 infections are reportable to World Organization for Animal Health (OIE).
Summary by Dennis Senne 2005

3. Avian Influenza Low pathogenic avian influenza (LPAI)
Associated with mild illness in poultry
Can evolve into highly pathogenic viruses
Associates poultry outbreaks worldwide
High pathogenic avian influenza (HPAI)
Causes high mortality in domestic poultry
Subtypes H5 and H7
Avian Influenza

4. H5N1 virus Electron micrograph of avian influenza H5N1 virus
This is the Highly Pathogenic Avian Influenza virus that is currently of major concern to domestic bird industry. There is currently no H5N1 infection in domestic poultry at this time although this virus has been cultured from migratory water fowl.
Avian Influenza

5. Host Range
Parakreets
Domestic Poultry
Avian Influenza

6. Peri-domestic species
Occasional isolations of avian influenza virus from starlings and house sparrows (in contact with infected poultry)
Replication of some avian influenza virus in these species (experimental)
Ja The ones most likely to be seen in contact with poultry
Avian Influenza

7. Natural Reservoirs of Influenza A Viruses
Wild aquatic birds
Majority are represented
by two Orders:
1. Anseriformes (ducks,
geese, and swans)
Avian Influenza

8. Natural Reservoirs of Influenza A Viruses
2.Charadriiformes (gulls,
terns, and shorebirds)
Usually show no
clinical disease
Dennis Senne
Avian Influenza

9. The Muscovy Ducks Natural Reservoir
Waterfowl and shorebirds (wild and domesticated) are the major natural reservoir of influenza viruses. Wild waterfowl are asymptomatic, may excrete virus in the feces for long periods, may be infected with more than one subtype, and often do not develop a detectable antibody response.
Avian Influenza

10. How are these viruses transmitted and maintained in these species?
Transmission: Fecal/Oral route
Heavy fecal shedding by infected ducks
Long term persistence in water
Isolation of AIVs from surface water
Maintenance: Bird to bird
Persistence in environment ja
Avian Influenza

12. Species Affected Wild birds Cage birds Poultry Mammals Waterfowl
Shorebirds
Cage birds
Passerines
Poultry
Mammals
Pigs, horses, mink, cats, dogs, ferrets, stone martens, palm civets & others
Avian influenza viruses mainly infect birds. In wild species, these viruses are especially common among birds that live in wetlands and other aquatic environments. Waterfowl and shorebirds appear to be the natural reservoirs for the influenza A viruses, and carry all of the known subtypes. Important reservoir hosts include ducks, geese, swans, gulls, terns and waders. The vast majority of viruses found in birds are LPAI; HPAI viruses are usually detected mainly in poultry. Among cage birds, most avian influenza virus infections have been recorded in passerine birds. Psittacine birds are rarely affected. Some strains of avian influenza viruses may occasionally cause disease in mammals including pigs, horses, mink, cats, dogs, ferrets, stone martens, palm civets, marine mammals and other species. The Asian lineage H5N1 (HPAI) viruses seem to have a particularly broad host range.
Photos: Chicks (USDA); Duck (Clint May, CFSPH).

13. Avian Influenza in Poultry
AIV is not normally found in domestic ducks, chickens and turkeys
Transmission of AIV from wild birds to domestic poultry species occurs commonly (ducks>turkeys> chickens)
AIV on rare occasions may become established in chickens and turkeys and result in serious disease outbreaks
AIV once adapted to chickens and turkeys can be difficult to eradicate

14. Clinical Signs Incubation period 3-5 days Severe depression
Decreased food and water consumption
Drastic decline in egg production
Many birds affected
Avian Influenza

15. Turkeys with Avian Influenza
Turkeys with Avian Influenza
Many birds are depressed and huddling
Avian Influenza

16. Note swollen head, and discharges. Wattle is cyanotic and necrotic.
Avian Influenza

17. Clinical Signs
Huddling
Avian Influenza

18. Clinical Signs Ruffled feathers S/C swelling of head & neck area
Swollen, cyanotic (blue) combs & wattles
Conjunctivitis with resp. signs
Dehydration
Huddling
Nasal & oral cavity discharge
Coughing
Sneezing
Diarrhea
Sudden death
Avian Influenza

19. Ruffled feathers
Respiratory Symptoms
Avian Influenza

20. END Corrie
Avian Influenza
2006

21. Swollen blue, cyanotic combs and wattles
Avian Influenza

22. Swollen blue, cyanotic combs and wattles
Avian Influenza

23. Clinical Signs
Edema/necrosis of comb/wattle
Cyanosis
Avian Influenza

24. HPAI - Cyanotic comb of an infected chicken
on the left compared to a normal chicken on the right.
Avian Influenza

25. Clinical Signs
Subcutaneous hemorrhage
of shanks
Avian Influenza

26. Subcutaneous hemorrhage of shanks
Avian Influenza

27. Hemorrhage of the shanks and hocks
Avian Influenza

28. Clinical Signs
Neurological signs (nervous signs) similar to Exotic Newcastle Disease
Avian Influenza

29. EXD Corrie
Avian Influenza
2006

30. Neurological signs
Avian Influenza

31. Neurological signs
Cyanosis
Ruffled feathers
Avian Influenza

32. Neurological signs Hemorrhages on shanks Ruffled feathers
Corrie
Neurological signs
Hemorrhages on shanks
Ruffled feathers
Avian Influenza

33. Clinical Signs
Huddling
Sinusitis
Respiratory signs
Avian Influenza

34. END Corrie
Avian Influenza

35. Clinical Signs Sudden onset & high mortality Birds found dead
Avian Influenza

36. Post Mortem Lesions Lesions may be absent with sudden death
Avian Influenza

37. Lesions Head and neck edema Swollen and cyanotic combs and wattles
Petechial hemorrhages on internal membrane surfaces
Avian Influenza

38. Avian Influenza

39. Lesions
Excessive mucous exudate in the lumen of the trachea, or severe hemorrhagic tracheitis
Petechiae on the inside of the sternum, on the serosa and abdominal fat, serosal surfaces and in the body cavity
Avian Influenza

40. HPAI - Opened swollen wattle.
Lesions
HPAI - Opened swollen wattle.
Avian Influenza

41. Hemorrhages and edema
Avian Influenza

42. Edema
Avian Influenza

43. Petechial hemorrhages on internal membrane surfaces
Avian Influenza

44. Lesions
Hemorrhages of the trachea
Avian Influenza

45. Hemorrhages of the trachea
Avian Influenza

46. Avian Influenza

47. Lung hemorrhage and edema
Avian Influenza

48. Note hemorrhages and edema around the heart
Avian Influenza

49. Severe kidney congestion, sometimes with urate deposits in the tubules
Hemorrhages on the mucosal surface of the proventriculus, particularly at the juncture with the gizzard
Hemorrhages and erosions of the gizzard lining
Hemorrhagic foci on the lymphoid tissues in the intestinal mucosa
Avian Influenza

50. Hemorrhages of the intestine
From FAO
Avian Influenza

51. proventriculus, particularly at the juncture with the gizzard
Hemorrhages on the
mucosal surface of the
proventriculus, particularly
at the juncture with
the gizzard
Avian Influenza

52. Hemorrhage in intestinal serosa, mucosa
Avian Influenza

53. Hemorrhagic foci on the lymphoid tissues in the intestinal mucosa
Avian Influenza

54. Lesions
Severe congestion of the musculature
Avian Influenza

55. Intra-follicular tissue dark red.
BVs over ova: prominent & congested. Large, poorly demarcated red foci on follicles.
Intra-follicular tissue dark red.
No mature ova on ovary. Some follicles becoming paler & flaccid (atresia).
Depending on timing of lay cycle, lack of mature follicles & increased atresia indicate dis.
Avian Influenza

56. Differential Diagnosis
Clinically indistinguishable from virulent Newcastle Disease
Suspect with:
Sudden death
Drop in egg production
Facial edema, cyanotic combs and wattles
Petechial hemorrhages
Avian Influenza

57. Differential Diagnosis
Velogenic ND
Acute fowl cholera
Respiratory diseases, esp. ILT, Avian pneumovirus, IB
Chlamydia
Mycoplasma
Water deprivation
Heat exhaustion
Toxins – food or water borne
Avian Influenza

58. Disease Summary
Avian influenza is a contagious viral dis. of birds characterized by:
Respiratory signs,
Depression and
Reduced feed and water intake.
In layers, decline in egg prod. & quality.
Two pathotypes:
Most common is low pathogenic AI (LPAI) &
Other is highly pathogenic AI (HPAI).
Avian Influenza

59. Disease Summary Most virulent HPAI was once called fowl plague.
At “1981 International Symposium on Avian Influenza”, term fowl plague was replaced with term "highly virulent" influenza virus inf.
Avian Influenza epidemic of required yet new terms to describe relative pathogenicity of dif. isolates of same serotype:
Nonpathogenic,
Low-pathogenic &
Highly pathogenic).
Avian Influenza

60. Disease Summary Avian Influenza outbreaks … throughout world.
LPAI is common in large turkey-producing areas, particularly where semi-confinement or range-rearing is still widely practiced.
In the United States, most outbreaks have been in turkeys. A few outbreaks have occurred in chickens.
Humans, horses, pigs, and some wildlife species may be infected with influenza viruses, and a cycle between birds and swine exists.
Avian Influenza

61. Disease Summary
A chicken outbreak of LPAI in 1983 mutated into HPAI in resulting in a federal-state eradication program that required the depopulation of 17 million birds. Similar outbreaks of LPAI in Mexico in 1992 and Italy in 1999 also mutated into HPAI causing severe losses.
Avian Influenza

62. Disease Summary
Influenza viruses vary widely in pathogenicity and ability to spread among birds. Two pathotypes are recognized: LPAI and HPAI. These pathotype designations are derived from laboratory inoculation of 8 susceptible chickens; LPAI isolates cause death in 0 to 5 of 8 chickens and HPAI isolates cause death in 6 or more. Although most H5 and H7 isolates are low path viruses, so far all HPAI outbreaks have been due to H5 or H7 viruses.
Avian Influenza

63. Corrie
Avian Influenza

64. MCQs
Choose the MOST CORRECT or THE ONLY CORRECT answer for the following questions:
Which type of influenza virus does cause AI?
Type A
Type B
Type C
Types A & B
Types B & C
Avian Influenza (AI)

65. ILTV, vNDV and IBV and Mycoplasma gallisepticum
2. Which of the following tests is used to confirm that and isolated virus is Type A influenza virus?
3. Which of the following virus is known to induce haemorrhagic tracheitis in chickens? HA HI
ILTV
AGIDT
vNDV
VN test
ILTV, vNDV and AIV
ILTV, vNDV and IBV
ILTV, vNDV and IBV and Mycoplasma gallisepticum
Avian Influenza

66. Haemagglutinin antigen Matrix antigen and Nucleocapsid antigen
4. The double immunodiffusion test is used to define the type of influenza virus. This serological test identifies which of the following antigens of influenza virus?
Matrix antigen
Nucleocapsid antigen
Haemagglutinin antigen
Matrix antigen and Nucleocapsid antigen
Haemagglutinin antigen and neuraminidase antigen
Avian Influenza

67. 5. Migratory waterfowl are considered as an important source of infection of poultry with which of the following viral diseases.
6. How many dif. haemagglutinins & neuraminidase antigens have been defined in type A influenza virus? AI
8 & 6, respectively ND
9 & 6 , respectively AE
c. 13 & 8, respectively IB
d. 13 & 9, respectively
ILT
e. 15 & 9, respectively
Avian Influenza

68. NDV &Cryptosporidium bailey AIV & Cryptosporidium bailey
7. Type A influenza virus is subtyped on the basis of which type of the following antigens?
8. 14 wk old range turkeys had markedly swollen sinuses. Birds were seronegative for Mycoplasma gallisepticum, M. synoviae and M. meleagridis. & attempts to isolate Mycoplasma were unsuccessful. Which of the following inf. agents should be considered as possible cause of the problem?
Haemagglutinins
Neuraminidase
Nucleocapsid and Matrix antigens
Haemagglutinins and Neuraminidase
Haemagglutinins and Matrix antigens
NDV and AIV
NDV &Bordetella avium
AIV &Bordetella avium
NDV &Cryptosporidium bailey
AIV & Cryptosporidium bailey
Avian Influenza
2006

69. 10. What is the classical cl. manifestation of AI in turkeys & chickens?
Resp. signs
Neurological signs
Diarrhoea
Only mortality
11. All isolates of “highly pathogenic” AIV are which of the following Hemagglutinin subtype?.
H3 & H7
H5 & H7
H1 & H3
H1 & H5
H1 & H7
9. Evidences suggest that turkeys may contract AIV from which of the following farm animals?
Cattle
Sheep
Pigs
Horses
Avian Influenza
2006