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

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

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

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

Host Range Parakreets Domestic Poultry Avian Influenza

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

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

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

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. http://www.cvm.umn.edu/ai/ Avian Influenza

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

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).

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

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

Turkeys with Avian Influenza www.cvm.umn.edu/img/assets/19564/02205brd-x.jpg Turkeys with Avian Influenza Many birds are depressed and huddling Avian Influenza

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

Clinical Signs Huddling Avian Influenza

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

Ruffled feathers Respiratory Symptoms Avian Influenza

END Corrie Avian Influenza 2006

Swollen blue, cyanotic combs and wattles Avian Influenza

Swollen blue, cyanotic combs and wattles Avian Influenza

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

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

Clinical Signs Subcutaneous hemorrhage of shanks Avian Influenza

Subcutaneous hemorrhage of shanks Avian Influenza

Hemorrhage of the shanks and hocks Avian Influenza

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

EXD Corrie Avian Influenza 2006

Neurological signs Avian Influenza

Neurological signs Cyanosis Ruffled feathers Avian Influenza

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

Clinical Signs Huddling Sinusitis Respiratory signs Avian Influenza

END Corrie Avian Influenza

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

Post Mortem Lesions Lesions may be absent with sudden death http://www.avian-influenza-disinfectant.com/avian_influenza.htm Avian Influenza

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

Avian Influenza

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

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

Hemorrhages and edema Avian Influenza

Edema Avian Influenza

Petechial hemorrhages on internal membrane surfaces Avian Influenza

Lesions Hemorrhages of the trachea Avian Influenza

Hemorrhages of the trachea Avian Influenza

Avian Influenza

Lung hemorrhage and edema Avian Influenza

Note hemorrhages and edema around the heart Avian Influenza

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

Hemorrhages of the intestine From FAO Avian Influenza

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

Hemorrhage in intestinal serosa, mucosa Avian Influenza

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

Lesions Severe congestion of the musculature Avian Influenza

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

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

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

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). http://www.cvm.umn.edu/ai/ Avian Influenza

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 1983-1984 required yet new terms to describe relative pathogenicity of dif. isolates of same serotype: Nonpathogenic, Low-pathogenic & Highly pathogenic). http://www.cvm.umn.edu/ai/ Avian Influenza

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. http://www.cvm.umn.edu/ai/ Avian Influenza

Disease Summary A chicken outbreak of LPAI in 1983 mutated into HPAI in 1983-1984 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. http://www.cvm.umn.edu/ai/ Avian Influenza

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. http://www.cvm.umn.edu/ai/ Avian Influenza

Corrie Avian Influenza

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)

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

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

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

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

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