Lecture 8- Avian influenza and infectious bursal disease SV.pdf

1. Avian Influenza 2. Infectious Bursal Disease Fall, 2024 Alfred Chikweto (BVM, MSc, PhD) ([email protected]) SESSION ID: pthb516 Avian Influenza (Fowl plague) o Worldwide distribution o Hosts oAll avian species, but turkeys main target o Most...

1. Avian Influenza 2. Infectious Bursal Disease Fall, 2024 Alfred Chikweto (BVM, MSc, PhD) ([email protected]) SESSION ID: pthb516 Avian Influenza (Fowl plague) o Worldwide distribution o Hosts oAll avian species, but turkeys main target o Most outbreaks have been in turkeys in the USA o First outbreak was during 2002 in Virginia o4.7 million chickens and turkeys were depopulated (Akey BL. Low- pathogenicity H7N2 avian influenza outbreak in Virginia during 2002. Avian Dis. 2003;47(3 Suppl):1099-1103. Doi: 10.1637/0005-2086-47.s3.1099) Etiology ❑Orthomyxovirus o Type A influenza virus o Strains of AI virus o Classified based on pathogenicity o High pathogenicity avian influenza (HPAI) virus o Subtypes are classified according to their surface proteins; hemagglutinin (H) and neuraminidase (N) o To date all highly pathogenic influenza viruses have been H5 and H7 subtypes o Majority of outbreaks involve H5N1 o Zoonotic o Low pathogenic avian influenza virus (LPAI) Epidemiology oExcreted from mouth, nares, cloaca and conjunctiva from infected birds oTransmitted by direct contact or indirect through virus contaminated fomites oWild and domestic waterfowls are main reservoirs of the virus oMigratory birds transmit virus intermittently http://oie.int/animal-health-in-the-world Global seasonal trend of HPAI https://www.woah.org/app/uploads/2024/02/hpai-situation-report-20240220.pdf 5 Avian influenza-HPAI outbreaks- Feb. 20. 2024 6 https://www.woah.org/app/uploads/2024/02/hpai-situation-report-20240220.pdf Clinical Signs oGreat variation from mild depression to high mortality o Depending on o Age oSpecies of the host oVirulence of the virus o Immunity oConcurrent infection Clinical Signs 1. HPAI viruses oWild birds and domestic ducks oFew clinical signs are seen oIn chickens and turkeys oSigns vary from sudden death to less fulminating disorders o Later in 3-7 days PI chickens and turkeys show oNervous disorders o Torticollis, opisthotonos and inability to stand o Decline in feed and water consumption, lower egg production, mild respiratory signs such as sneezing, coughing and rales may be seen oMortality and morbidity are very high [50%-90%] Clinical signs 2. Low pathogenicity AI viruses: o Wild birds o No clinical signs and no mortality o In domestic poultry (chicken, turkey) o Frequent clinical signs are respiratory o Coughing, sneezing, rales, and lacrimation o Decreased feed and water consumption, lower egg production and occasional diarrhea may be seen o There is high morbidity and low mortality (