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Avian influenza

Avian influenza. Saliha Hammoumi CIRAD Montpellier, France. Outline. Influenza Virus description Influenza epidemiology Poultry / wild birds / humans Current projet: TCP FAO Surveillance of AIV in wild birds in Africa, Middle-East and in Eastern Europe. Influenza Virus. Influenza virus.

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Avian influenza

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  1. Avian influenza Saliha Hammoumi CIRAD Montpellier, France

  2. Outline • Influenza Virus description • Influenza epidemiology • Poultry / wild birds / humans • Current projet: TCP FAO • Surveillance of AIV in wild birds in Africa, Middle-East and in Eastern Europe

  3. Influenza Virus

  4. Influenza virus • Family: Orthomyxoviridae • Enveloped • 8 segments single stranded (-) sense RNA • Three main types • Type A • Multi-species • Type B • Human • Type C • Human and pig

  5. Influenza A Virus • Multi-species • Mammals (human, pig and horse) • Birds • The most virulent group • Classification in subtypes by surface antigenes • Hemagglutinine (H or HA) : 16 • Neuraminidase (N or NA) : 9 • All HxNy types in waterfowl

  6. Surface antigens and subtypes • Cleaves sialic acids and permits the liberation of viral particles Attachment site on host cells (receptor = sialic acid)

  7. Designation of influenza viruses • Type/ species of the isolate if non human /place of isolation/ number of strain/year of isolation (subtype) • A/Hong-Kong/1/68 (H3N2) • A/eq/Miami/1/63 (H3N8)

  8. HA subtypes and host distribution

  9. Influenza variability: antigenic drift • Spontaneous genetic mutations due to the absence of proof-reading activity of the polymerase. • Selection of viruses mutated on H and/or N gene due to selection pressure of antibodies Conserved immunity Epidemic • No antigenic modification • Antigenic modification

  10. Influenza variability: antigenic shift New combinations of H and N can occur by reassortments of the RNA encoding H and N proteins when cells are coinfected with 2 different sub-type viruses People, pigs and aquatic birds are the principle variables associated with the interspecies transfer with pigs and ducks acting as « mixing vessels  »

  11. Pandemics

  12. Origin of the H5N1 bird flu It is proposed that the H5N1 influenza virus that infected humans in Hong Kong in 1997 is a re-assortant; The HA gene have come from A/Goose/Guandong/1/96 (H5N1) influenza virus and the internal genes from a EurAsian avian influenza virus. Webster 2002

  13. Avian influenza • Pathogenicity based on disease severity on poultry and/or genetics • Low pathogen (LPAI) • Subtypes H1 to H16 • High pathogen (HPAI) • Some strains of H5 or H7 subtypes (possibly H6 or H9) • Some LPAI strains of H5 or H7 subtypes may mutate in HPAI

  14. Hemagglutinine and HPAI

  15. Influenza epidemiology

  16. Transmission • Source of infection • Poultry • Migratory waterfowl • Transmission • Droppings, secretions from the eyes and nose of infected birds • Shared drinking water or food • Manure, equipment, vehicles and crates

  17. HPAI Morbidity / Mortality • Merely 100% in commercial poultry flocks • Death within 2 to 12 days after the first signs of illness

  18. Cumulative H5N1 cases in poultry and wild birds

  19. Current situation in poultry and wild birds

  20. Cumulative H5N1 human cases

  21. Current situation in humans

  22. TCP FAO : Surveillance of AIV in wild birds in Africa, Middle-East and in Eastern Europe

  23. UA 463 RO 200 TR 658 TN 88 MA 486 IR 1030 EG 2400 MR 665 ML 1871 TC 1100 NG 604 SD 421 ET 817 KE 509 ZM 704 MW 1063 Sampling sites number of tracheal and cloacal samples collected per site analysed samples analysis in process

  24. Sampling procedure -80°C Shipment under dry ice

  25. Laboratory analyses procedure Mix Sample sorting 88 samples pooled in a 96 deep well plate + 6 ten-fold dilutions of A/PR/8/34 Discard Swabs RNA extraction of 100 µl of 88 samples in 50 min in a final volume of 50 µL • Influenza A Q RT-PCR : M gene • Primers M+25, M-124 and the probe M+25 (Spackman et al, 2002) • Brilliant QRT-PCR one-step Master mix kit (Stratagene) Positive samples • Influenza H5 and H7 Q RT-PCR : • primers and probes recommended by the reference laboratory VLA (Weybridge, UK) • one-step RT-PCR kit (Qiagen) Positive samples RT-PCR on HA cleavage site Sequencing and pathotyping

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