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Highly Pathogenic Avian Influenza (HPAI) on the Poultry Farm

Highly Pathogenic Avian Influenza (HPAI) on the Poultry Farm

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Highly Pathogenic Avian Influenza (HPAI) on the Poultry Farm

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  1. Highly Pathogenic Avian Influenza (HPAI) on the Poultry Farm

  2. Learning Objectives • Describe normal transmission of AI • Describe development of HPAI (vs. LPAI) • Describe control measures • Surveillance • Enhanced biosecurity • Movement control • Destruction of contaminated birds and fomites • Role of vaccines and antivirals

  3. Avian Influenza Overview • Avian influenza (AI) – first isolated in 1955 • High-pathogenicity avian influenza (HPAI) – causes contagious illness, death in birds; Low-pathogenicity (LPAI) causes mild to no illness • Vast majority of AI viruses found in birds do not represent a public health concern

  4. Hemagglutinin Neuraminidase M2 PB1 PB2 PA HA NP NA MA NS M1 Matrix Avian Influenza Overview • Virus is characterized by H and N type (surface proteins). • 144 possible combinations of the virus, based on 16 H types and 9 N types • AI viruses mutate easily; only H5 and H7 viruses known to have the potential to mutate from an LPAI to an HPAI form. • AI viruses vary widely in pathogenicity from strain to strain. Therefore not all H5N1 viruses are infectious for people or pathogenic to poultry.

  5. Species Affected Genetic Reservoirs H3, H7 H1, H2, H3 Intermixing H5N1 Commercial, LBMs Others H10 H1-12 H14-15 H1-2, 4-7, H9-13, 15-16 Other Aquatic Birds? H1, H3, H4, H7, H13 H1, H3

  6. Pathogenicity of AI • AI strains characterized by pathogenicity in chickens • LPAI (Low-pathogenic avian influenza) • Mild disease in poultry • Most strains are LPAI • LPAI H5 and H7 strains can mutate into HPAI • HPAI (Highly pathogenic avian influenza) • Severe illness and high fatality in poultry • Some birds have no illness

  7. Three HPAI Findings in U.S. • 1924 – “Fowl Plague” affected live bird markets in the Northeastern U.S. Etiology was not known until 1955. • 1983 – destruction of 17 million birds in PA and VA due to HPAI H5N2 • 2004 – HPAI H5N2 quickly contained and eradicated in TX

  8. Development of HPAI • Low pathogenic AI strains that are most capable of mutating into HPAI and causing epizootics • H5 and H7 • Most H5 and H7 are LPAI • Disease • Human HPAI infection via contact with infected sick or dead birds • Mild human LPAI infections have been documented • Wild birds can introduce LPAI into domestic flocks • Can evolve into HPAI • Aggressive intervention required for LPAI

  9. Signs of LPAI Influenza in Poultry • Wild waterfowl, gulls, shorebirds are natural hosts for influenza viruses • Usually no symptoms • Infection in non-reservoir can result in either: • No outward disease (LPAI) • Mild infection (LPAI) • Ruffled feathers • Reduced egg production • Respiratory symptoms • Can be easy to miss!

  10. Signs of HPAI Infection in Birds • Causes more lethal infection • Difficult to miss - severe disease/sudden onset • Facial edema, swollen and cyanotic combs and wattles, drastic decline in egg production • Internal hemorrhaging of lungs and other organs • Rapid contagion • Mortality near 100% within 48 hours

  11. Signs of HPAI Infection in Birds

  12. Domestic and wild birds Ducks, geese, sparrows, poultry, pets Pigs, horses, marine mammals, ferrets, minks Natural infection contracted from exposure to birds Tigers, leopards, domestic cats, dogs H5N1 infections from ingestion of infected poultry Avian Influenza in other Animals

  13. How is the virus spread among birds? • Direct contact between healthy and infected birds • Infected fecal matter • Can be found on surface of unwashed egg shells from infected birds

  14. Fomites. Tools, equipment, and other contaminated items Contact with carcasses. Carcasses should be buried, incinerated, composted, or rendered Other Sources of Infection

  15. Humans Possibly hands, hair, clothing, footwear Possibly contaminated equipment Possibly inhalation of aerosolized virus (self inoculation) Potential Sources of Infection for Humans Investigators must practice biosecurity when entering / leaving a potentially contaminated farm

  16. Measures for Prevention, Control and Eradication of HPAI in Poultry • Increased disease surveillance in high risk areas • Increased biosecurity on poultry farms • Response (5 basic steps) -- • Quarantine, Eradicate, Monitor the area, Clean and Disinfect, and Test • Vaccination if necessary

  17. Types of Poultry-Raising & Biosecurity

  18. Sector 4 • Backyard production • Birds/products consumed locally 9/10/2004 Cayce. Malaysia

  19. Sector 3 • Low to minimal bio-security • Birds/products enter live bird markets or other local distribution systems Free range chickens Image source:

  20. Sectors 1 and 2 • Sector 2 • Moderate to high bio-security • Birds/products often marketed commercially • Sector 1 • High level bio-security • Birds/products marketed commercially Image source:

  21. Classification system for poultry production systems (FAO 2004)

  22. Ensure Biosecurity through Bioexclusion • Keep poultry indoors • Separate from the outside world • Remove or disinfect all sources of infection • Prevent unknown birds from entering flock • Control human, vehicular, and equipment traffic onto the farm • Use “all in – all out” production • Separate new poultry from flock • Clean and disinfect when “all out” AI can remain viable in tissue, feces and water for a long period of time (days to weeks)

  23. Biocontainment on Infected Farms • Depopulation of infected and exposed birds • Movement control • On and off farm • Bird markets and swap meets closed and disinfected • Testing of potentially infected birds • Surveillance for illness in birds

  24. Destruction and Disposal of Birds in Affected Area • Humanely depopulate birds and other animals • Carbon dioxide • Dislocate neck • Others • Effective disposal • Incineration • Bury • Compost • Digestion • Rendering • Cleaning and disinfection 3/1/2006 Reuters. Karachi

  25. Vaccination for Poultry • Inactivated whole AI virus • Effective against H5 subtype • Reduced amount of virus in environment • May have subclinical infection • Can still shed virus • Administered by injection • Vaccination maylimit exportation • Recombinant vaccines under development • H5 and H7 vaccination requires USDA approval

  26. Antivirals • Antivirals use only for humans • On March 20, 2006, the FDA published a proposed final rule to prohibit the extralabel use in poultry of two classes of approved human antiviral drugs in treating influenza. FDA is taking this measure to help preserve the effectiveness of these drugs for treating or preventing influenza infections in humans.Specifically, the order prohibits the extralabel use by veterinarians of anti-influenza adamantane (amantadine and rimantadine) and neuraminidase inhibitor (oseltamivir and zanamivir) drugs in chickens, turkeys, and ducks.

  27. Take Home Message • Isolate domestic birds from wild birds and waterfowl • Practice good biosecurity in all flocks • Need adequate surveillance system • Early detection and rapid response • AI response is always a joint effort Photo: Billy Karesh, Wildlife Conservation Society

  28. Helpful web sites • Centers for Disease Control: • World Health Organization: • World Organization for Animal Health: • UN Food and Agriculture Organization: • US poultry and Egg Industry Association • USDA Avian Influenza website

  29. Occupational Guidelines

  30. Occupational Guidelines • For persons in contact with healthy birds in HPAI-free zones • Increased vigilance and hazard communication • Standard Personal Protective Equipment (PPE) • Risk assessment for processing of species that may exhibit asymptomatic disease (e.g. ducks)

  31. Occupational Guidelines • For persons in direct contact with known or suspected HPAI materials • Training, basic infection control, PPE to include respirators and antiviral prophylaxis • Surveillance and monitoring of workers • Evaluation of ill persons

  32. Occupational Guidelines • For exposure to a known HPAI source • Disposable particulate respirators (N-95 or greater); or powered air purifying respirator • Current season influenza vaccine Reduces possibility of dual infection with human and avian influenza, which could lead to reassortment

  33. Occupational Guidelines • For persons in contact with live or dead poultry or materials later identified as HPAI • Medical evaluation • If symptomatic, collection of specimens for viral testing • Post-exposure prophylaxis • Surveillance for respiratory-related symptoms • Fever • Respiratory symptoms • Conjunctivitis