بسم الله الرحمن الرحيم

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

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

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

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

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

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

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

Avian Influenza HPAI emerges from LPAI

Avian Influenza Not all H5 and H7 viruses are HPAI

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

Reassortment (antigenic shift) Major Antigen AI Virion RNA Segments

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

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

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)

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 1994-1995. 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 1994-2003 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 1995-2003 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 2003-2009 (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).

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

2005

2006

2007

2008

2009

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.

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

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

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

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

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

Sinusitis Sinusitis

Tracheitis

Hemorrhagic- necrotic Pancreatitis

Gross lesions

In layers and breeders, reduce egg production

(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)

Thank you sm.hassan04@gmail.com