Avian Influenza Summary

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Asher Bennett
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1 Avian Influenza Summary Worldwide distribution Sporadic outbreaks of High Path H5 and H7 in poultry Wild aquatic birds are reservoirs for all avian influenza viruses Viruses can change quickly (mutation) Avian-origin influenza viruses contribute to outbreaks in humans and other animals Virus is inactivated by most disinfectants Vaccination not done in the US, but is done in countries with HPAI Good biosecurity is effective prevention

2 HP Avian Influenza Classic Signs & Lesions: Sudden onset, moderate to high morbidity and mortality. Edema of head Cyanosis/necrosis of comb/wattle Subcutaneous hemorrhage

3 HPAI H5N1 Outbreak Unique Features Unprecedented spread to three continents Unprecedented number and variety of species affected Many avian and multiple mammalian species are susceptible Spill-over to wild birds, causing mortality in wild waterfowl Involvement of waterfowl in virus spread Unprecedented changes in the virus High mortality in humans

4 HPAI H5N1 Outbreak >250 million chickens died/killed >60 Countries affected (27 in 2008) 391 confirmed human cases (15 countries) fatalities Jan

5 All HPAI Outbreaks from Jan 2011 to Jan 2012

Avian Influenza Virus Orthomyxovirus Type A Humans are susceptible to A, B, and C Enveloped virus RNA Single stranded (negative sense) 8 segments, codes 10 proteins Major

6 Avian Influenza Virus Orthomyxovirus Type A Humans are susceptible to A, B, and C Enveloped virus RNA Single stranded (negative sense) 8 segments, codes 10 proteins Major surface proteins Hemagglutinin (H1-H16) Neuraminidase (N1-N9) 144 potential combinations H5N1, H7N7, H9N2 etc. PB1 PB2 PA HA NP NA MA NS M1 Neuraminidase Hemagglutinin M2

7 Avian Influenza Viruses Change Frequently Antigenic Drift: mutations in H gene cause minor antigenic changes to H protein Continuous process Limits protective immunity Antigenic Shift: Replacement of H or N Genetic re-assortment (human and animal viruses) Insertion of large section of extraneous RNA near the HA cleavage site virulence shift Emergence of novel (pandemic) strains

Anseriformes: ducks, geese, swans -Mallards and other dabbling ducks have highest isolation rates.

8 Natural Reservoirs of Influenza A Viruses Wild aquatic birds Majority of influenza isolates comes from two orders: 1. Anseriformes: ducks, geese, swans -Mallards and other dabbling ducks have highest isolation rates. 2. Charadriiformes: gulls, terns, and shorebirds such as ruddy turnstones Typically, no clinical disease except: 1. South Africa in H5N1 infection in wild birds in Asia

9 Ecology of Influenza A H3 H1, H2, H3 H1N1 H5N1 Genetic Reservoirs Intermixing H3, H7 Commercial, LBMs Others H1-12 H14-15 H1-2, 4-7, H9-13, H10 H1, H3 Other Aquatic Birds? Modified from D. Swayne H1, H3, H4, H7, H13

10 Emergence of HPAI Reservoir Genetically stable and low path in natural host Exposure/adaptation to domestic species that are not natural hosts Asian HPAI H5N1 Mutation- H5/7 may evolve to HP Most HPAI

11 Classification of Avian Influenza Low Pathogenicity (LPAI) Localized infection No to mild disease Any subtype (H1-H16) Waterfowl (gut) Domestic birds (resp) LP H5 and H7 in poultry are reported to OIE Highly Pathogenic (HPAI) Acute, systemic disease High mortality H5 & H7 subtypes only Affects primarily poultry (chickens, turkey, etc) Reported to OIE

12 Avian Influenza Factors Influencing Pathogenicity: Only H5 or H7 subtypes are HP, but the majority of H5 and H7 are LP Polygenic trait, but HA plays dominant role Multiple basic amino acids at HA cleavage site Glycosylation sites near HA cleavage site Remember: pathogenicity in the field is highly variable depending not only on the virus, but also the species and age of bird infected, concurrent infections, and other factors

13 Highly Pathogenic Avian Influenza USDA/OIE definition: 1. Any influenza virus that kills 6, 7, or 8 of 8 chickens (75% mortality) or IVPI> Any H5 or H7 subtype that does not meet the criteria in item 1, but has an amino acid sequence at the cleavage site of the hemagglutinin that is compatible with other HPAI viruses Note: The OIE also is notified when low path H5 and H7 is found in domestic poultry.

14 Sources of virus Transmission Routes of transmission Major Infected poultry flocks and live bird markets Feces/resp secretions Infected wild waterfowl Minor Uncooked infected poultry products H1/H3 from swine to turkeys Pet birds Oral - feces or cannibalism Aerosol IN, IC, IP, IM, IV, IC Fomites People Equipment Vehicles Feed and water Rodents, sparrows, etc Wind (less than 0.5mi)

15 Incubation and shedding of virus Incubation period of hours to 3 days Duration of virus shedding is highly variable More important than individual shedding is flock shedding of virus AI viruses can be maintained for long periods in domestic and wild flocks via individual, susceptible birds

16 Virus Titer (log 10) Stability of Hong Kong H5N1 Virus in Feces at Environmental Temperatures 5 4 Wet Feces (4 C) Dry Feces (25 C) Wet Feces (35 C) Days at Condition Shortridge et al Wet Feces (25 C)

17 Common Findings with Low Path AI Flocks with respiratory disease Flocks with decreased egg production Flocks with decreased food/water intake Increased daily mortality >3 bird deaths/1000 for 2 days These characteristics are not specific to AI Many possible differential diagnoses at this stage These signs may only be identified retrospectively after routine serologic surveillance detects LPAI

18 LP Avian Influenza Coughing, sneezing, rales Sinusitis, tracheitis, air sacculitis Bronchopneumonia w/ secondary pathogens (P. mult, E. coli) Epiphora Depression and huddling Ruffled feathers I. Capua D. Halvorson D. Halvorson

19 LP Avian Influenza Rough, misshapen eggs Hemorrhage in ovary Oviduct edema Egg yolk peritonitis Catarrhal enteritis Urates in kidney D. Swayne D. Swayne

20 Common Findings with HPAI Sudden onset and rapid spread Mod to high morbidity and mortality (>20 dead/1000/day) Sudden death Severe depression, drop in feed/water consumption Cough, sneeze, nasal discharge Ataxia, tremors, torticollis Dramatic decreased egg production and abnormal eggs

21 HPAI

22 HPAI Dr. H K Wong, Hong Kong Zoo

23 HPAI

24 HPAI Dr. A. Wilson, NVSL Asian H5N1

25 HPAI

26 HPAI

27 HPAI

28 HPAI Differential diagnosis Respiratory disease Infectious laryngotracheitis (ILT) Infectious bronchitis (IB) Fowl cholera (P. multocida) Mycoplasma gallisepticum Acute high mortality Newcastle disease Water deprivation Heat exhaustion Toxins

29 Sample collection 1. Serology (Important diagnostic specimen) AGID, ELISA (type-specific), and HI/NI (subtype-specific) 0.5 to 1 ml of serum, plasma, egg yolk 4 C or minus 20 C Typically sample 30 birds per flock + AS AS AG - + AS

30 Sample collection for VI or rrt-pcr 2. Tissue Lung and spleen Ship samples in plastic bag, and then double bagged Do not pool tissues from different birds Typically sample 3-5 sick birds per flock 3. Swabs: oropharyngeal (OP) and cloacal (CL) Use sterile polyester swabs on plastic shafts Poultry: can pool 5/tube, but do not mix OP with CL swabs Water fowl use individual cloacal swabs Place swabs in 2-4ml brain-heart infusion (BHI) broth Shipping/Storage of tissue and swabs Short term: 4 C (up to 72 hours) Long term: minus 70 C (minus 20 C not recommended)

Diagnostics Virus Isolation Embryonating chicken eggs Expensive and labor intensive Special facilities (BSL-2, -3Ag) Test all sample types Sensitivity high (all subtypes), may have

31 Diagnostics Virus Isolation Embryonating chicken eggs Expensive and labor intensive Special facilities (BSL-2, -3Ag) Test all sample types Sensitivity high (all subtypes), may have low sensitivity to some wild bird influenza viruses Specificity low (grow many viruses, bacteria) Detection of AI is by HA Differentiation from other HA agents by HI e 2 days-2 weeks

($25-90K) Sensitivity high (similar to VI) (assuming using right primers)

32 Diagnostics Real Time RT-PCR (rrt-pcr) Target Influenza A virus (matrix gene) H5, H7, N1 subtypes validated Moderate cost/test ($8) Expensive equipment ($25-90K) Sensitivity high (similar to VI) (assuming using right primers) Specificity high, Time - rapid (3-5 hrs) Potential for high throughput Live virus not required

Diagnostics Antigen Capture Immunoassays Commercially available (several sources) Detection of influenza A virus Pen-side no special facilities required Sensitivity low/moderate (70-80% compared to

33 Diagnostics Antigen Capture Immunoassays Commercially available (several sources) Detection of influenza A virus Pen-side no special facilities required Sensitivity low/moderate (70-80% compared to VI, need 3-5 logs of virus) Good for testing sick or dead birds Low sensitivity for vaccinated populations, healthy birds, and live wild bird surveillance Specificity high Moderate cost ($7-8) and rapid (10-15 minutes) Synbiotics Flu Detect Test

34 Strategies: AI Control Prevention prevent introduction of AIV Control reduce economic impact limit spread Eradication total elimination of AIV Achieved through Biosecurity (exclusion and containment) Diagnostics and surveillance early detection Elimination of AI virus in infected poultry Reduce susceptibility through vaccination Education of producers and public

surveillance programs 2006 (>160,000 specimens) 2007 (>95,000 specimens) 2008 (>50,000 specimens)

35 National Biosecurity Import restrictions on poultry and poultry products countries with HPAI Heighten border surveillance for illegally imported poultry and poultry products Wild bird surveillance programs 2006 (>160,000 specimens) 2007 (>95,000 specimens) 2008 (>50,000 specimens) 2009 (>19,000 specimens) Imported live birds 30-day quarantine Laboratory testing for AIV Van Borm S, EID 2005

36 Farm Biosecurity Avian influenza is a preventable disease Protect poultry, feed and water from contact with reservoir hosts/feces All-in, all-out management ideally, with a single species and single age group Purchase birds from reputable, tested supplier and/or quarantine and test incoming birds Limit access to farm Provide clean clothing and boots to workers Clean and decontaminate all vehicles and equipment coming on to the farm Don t bring in equipment from other farms Avoid visiting other farms and live bird markets

37 Personal Biosecurity for HPAI AI PPE recommendations from the CDC See website for complete details Educate staff on disinfection, hygiene, etc. Disposable nitrile or vinyl gloves Disposable coverall with impermeable apron Shoe covers or boots, which can be disinfected Safety goggles Respirator (N-95, N-99, N-100), requires fit testing Prophylactic antiviral medications Seasonal flu vax and medical surveillance of workers

38 Iodophores Phenolics Quaternary ammoniums Ethanol Bleach Peroxygens (Virkon-S)

39 Food Safety Eating properly handled and cooked poultry and eggs is safe The chance of HPAI infected meat getting into the human food chain in the US is extremely low Wash hands with warm, soapy water for 20 seconds Wash utensils with hot, soapy water Sanitize cutting boards with dilute bleach Cook poultry to an internal temperature of 165 F

40 Control and Eradication Vaccination not a stand alone control method Advantages Reduce viral shedding Prevent illness and death (does not prevent infection) Disadvantages No cross protection between subtypes Can interfere with diagnostics and surveillance Can hide clinical signs Impairment to international trade unless DIVA is used Vaccine bank

41 US Surveillance Programs Federal, State and Private laboratories Diagnostic surveillance Unexplained respiratory disease, decreased egg production, and increased mortality FADD investigations Live bird market surveillance Commercial producers surveillance via NPIP and national H5 and H7 LPAI control program Wild Migratory Bird surveillance

Newcastle Disease (ND)

Newcastle Disease (ND) Highly contagious viral disease of chickens, turkeys, and most other species of birds. The most severe form of the disease in chickens is characterized by high mortality with hemorrhagic