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Avian Influenza

Avian Influenza. Contents. Avian influenza/ Occurrence of Avian influenza A virus infections of humans History of influenza Economic Impact H5N1 Epidemiology Clinical manifestations in birds and human / diagnosis / treatment Prevention /control

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Avian Influenza

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  1. Avian Influenza

  2. Contents • Avian influenza/ Occurrence of Avian influenza A virus infections of humans • History of influenza • Economic Impact • H5N1 • Epidemiology • Clinical manifestations in birds and human / diagnosis / treatment • Prevention /control • The Philippines Preparedness and Response Plan • Tips for spreading the news

  3. Very contagious among birds and can make domesticated birds, including chickens, ducks, and turkeys, very sick and kill them

  4. Introduction Influenza, originated in birds / slowly mutated to human flu bird flu has always been around a new type of concern H5N1 virus. highly contagious killing 50 to 100% within 48 hrs Poultry outbreaks in neighboring India and China - alerted the government, UN agencies, donors and other organizations.

  5. Occurrence • Highly pathogenic avian influenza A (HPAI) viruses of the H5 and H7 / HA subtypes have been isolated occasionally from free-living birds in Europe and elsewhere. • Outbreaks due to HPAI were recorded in the Pennsylvania area, USA, in the years 1983-84 • Instances of Avian Influenza A Virus Infections of Humans

  6. Avian influenza A virus infections of humans since 1996 • H7N7, United Kingdom, 1996: 1 adult developed conjunctivitis / isolated low pathogenic avian influenza A (H7N7) (not hospitalized and recovered) • H5N1, Hong Kong, 1997: - In poultry and humans - the first timean avian influenza A virus transmission directly from birds to humans had been found to cause respiratory illness - 18 people -hospitalized / six -died. - Killed about 1.5 million chickens • H9N2, China and Hong Kong, 1999: Low pathogenic

  7. H7N2, Virginia, 2002: Outbreak among poultry, one person developed uncomplicated influenza-like illness • H5N1, China and Hong Kong, 2003: Two cases among members of a Hong Kong family that had traveled to China. One of them died. A family member died of a respiratory illness in China, but no testing was done. • H7N7, Netherlands, 2003: 89 people confirmed// 78 - conjunctivitis; 5 - conjunctivitis and influenza-like illness; 2 - influenza-like illness; 4 cases classified as “other.” One death - of acute respiratory distress syndrome. Authorities reported 3 possible instances of human-to-human H7N7 virus transmission from poultry workers to family members • H9N2, Hong Kong, 2003: Low pathogenic / a child was hospitalized with influenza-like illness and recovered. • H7N2, New York, 2003: low pathogenic/ In November with respiratory symptoms- a patient recovered

  8. H7N3, Canada, 2004: 2 poultry workers - conjunctivitis, /coryza.   Recovered.  • H5N1, Thailand and Vietnam, 2004: One instance of probable human-to-human spread of H5N1 virus in Thailand. 50 cases with 36 deaths • H5N1, Cambodia, China, Indonesia, Thailand and Vietnam, 2005: 98 human cases with 43 deaths • H5N1, Azerbaijan, Cambodia, China, Djibouti, Egypt, Indonesia, Iraq, Thailand, Turkey, 2006: In Azerbaijan, the most plausible cause of exposure to H5N1 in several instances of human infection is thought to be contact with infected dead wild birds (swans). 115 human cases with 79 deaths • H5N1, Cambodia, China, Egypt, Indonesia, Laos, Myanmar, Nigeria, Pakistan, Vietnam, 2007: Nigeria (January), Laos (February), Myanmar (December), and Pakistan (2007) confirmed their first human infections with H5N1. • H7N2, United Kingdom, 2007: Wales, influenza-like illness and conjunctivitis - 4 hospitalized cases. • H9N2, China, 2007: A 9-month-old girl with mild signs of disease.

  9. The bird flu outbreak… India • Since Jan 15 in West Bengal, • Confirmed in 13 of the 19 districts of West Bengal - alert has been sounded in many states – Uttar Pradesh, Uttarakhand, Haryana, Manipur and Bihar WHO has declared the situation in West Bengal as 'very serious and different' than the earlier outbreaks

  10. …in Nepal • Poultry outbreaks influenza virus A/H5N1- not reported in Nepal • Outbreaks in India and China alerted the government, UN agencies, donors and other organizations • Nepal - vulnerable - The large numbers of migrating birds - Traditional practice of mixed animal farming - Cross-border importation of both eggs and chickens - A large poultry population

  11. ….Nepal • February 2006 - the Government of Nepal endorsed a joint Health and Agriculture National Avian Influenza and Influenza Pandemic Preparedness and Response Plan (NAIIPPRP) • The plan created a joint health and agriculture Technical Subcommittee on Avian Influenza (TSCAI) under the National Disaster Relief Central Coordination Committee In August 2006 - Operational Plan for the period 2006-2010 was developed and endorsed by the TSCAI USD18.2 million plan has a human health and an animal health component, under the two responsible line ministries: Ministry of Health and Population and Ministry of Agriculture and Cooperatives

  12. History • 1878: First identified case in Italy • 1924-25: First U.S. cases HPAI • Low pathogenic avian influenza first identified mid-twentieth century • 1970’s: Migratory waterfowl carriers • Outbreaks in mink, seals and whales

  13. Economic Impact Economic losses from avian influenza vary depending on the strain of virus, species of bird infected, number of farms involved, control methods used and the speed of implementation of control or eradication strategies

  14. Economic Impact • Direct losses: • Disposal costs • High morbidity and mortality loses • Quarantine and surveillance costs • Compensation paid for elimination of birds. • 1978-2003: outbreaks of LPAI inMinnesota cost growers $22 million

  15. Economic Impact • 1983: U.S. outbreak (H5N2) • $65 million in losses • Destruction of 17 million birds • 30% increase in egg prices • 1999-2000: Italy outbreak (H7N1) • $100 million in compensation to farmers • 18 million birds destroyed • Total losses of $500 million

  16. Economic Impact • 1997: Hong Kong outbreak (H5N1) • $13 million loses • 1.4 million birds • 2001: Hong Kong outbreak (H5N1) • 1.2 million birds • $3.8 million

  17. Economic Impact • 2003: European outbreak (H7N7) • Over 33 million birds destroyed • (¼ of Netherlands’ poultry stock) • Total Cost of outbreak? • 2003-2004: SE Asia (H5N1) • 8 countries • >100 million birds destroyed • Cost? • 2004-2005: SE Asia and Eurasia The cost of this outbreak, since it is ongoing is yet to be determined

  18. H5N1 Human Case

  19. What is H5N1 virus? • The H5N1 strain is a new and extremely severe influenza virus • It has a unique capacity to jump the species barrier and cause severe disease in humans • The detection of few human cases, suggest that the virus may not be easily transmitted from birds to human at present

  20. The relationship between bird flu and influenza pandemic • H5N1 is a virus with pandemic potential, - Might ultimately adapt into a strain that is contagious among humans - Once this adaptation occurs it will no longer be a bird virus -it will be a human influenza virus

  21. 1918 Virus is an Avian Virus • Tissue / victim buried in permafrost • An avian virus that was adapted to humans • 25 amino acid changes from avian sequence • Some of these changes are already in the H5N1 virus

  22. Epidemiology

  23. Geographic Distribution • Worldwide distribution • Reservoir • Free flying aquatic birds: Ducks, geese, shorebirds, gulls, terns, auks • Outbreaks • The Netherlands, Australia, Mexico, U.S., SE Asia, Eurasia • Similarity to Newcastle Disease makes actual distribution difficult to define

  24. H5N1 AVIAN INFLUENZA THREAT: HUMAN CASES AT A GLANCE

  25. Morbidity/Mortality • Approaches 100%in commercialpoultry flocks • Deaths within 2 to 12 days after first signs of illness • Survivors -inpoor condition; do not begin laying eggs

  26. Key Influenza Viral Features Surface proteins (major antigens) •Hemagglutinin (HA) Site of attachment to host cells Antibody to HA is protective • Neuraminadase (NA) Helps to release virions from cells Antibody to NA can help modify disease severity

  27. “H5N1”

  28. The Influenza VirusTypes • Influenza Type A Can infect people, birds, pigs, horses, seals, whales, and other animals, but wild birds are the natural hosts for these viruses • Influenza Type B - normally found only in humans. - can cause human epidemics, they have not caused pandemics • Influenza Type C - cause mild illness in humans - do not cause epidemics or pandemics

  29. The Influenza Virussubtypes • Influenza type A viruses are divided into subtypes based hemagglutinin (HA) and neuraminidase (NA). There are 15 different HA subtypes & 9 different NA subtypes • Only some influenza A subtypes (i.e., H1N1, H1N2, and H3N2) are currently in general circulation among people. Other subtypes are found most commonly in other animal species. For example, H7N7 and H3N8 viruses cause illness in horses

  30. How are Avian Influenza Viruses different from Human Influenza Viruses? • Humans can be infected with influenza types A, B, and C. The only subtypes of influenza A virus that normally infect people are influenza A subtypes H1N1, H1N2, and H3N2 Between 1957 and 1968, H2N2 viruses also circulated among people, but currently do not • Only influenza A viruses infect birds. Wild birds are the natural host for all subtypes of influenza A virus. Typically wild birds do not get sick when they are infected

  31. How do outbreaks of avian influenza spread? • Within a country, spreads from farm to farm Large amounts of virus are secreted in bird droppings, contaminating dust and soil. Contaminated equipment ,vehicles, feed, cages or clothing/ shoes • From country to country through international trade in live poultry • Migratory birds can carry the virus for long distances

  32. Transmission of virus • Initial source of infection • Poultry, migratory waterfowl, pet birds • Spread by aerosol, shared drinking water, fomities • Virus in respiratory secretions and feces • Virus present in eggs laid by infected hens; unlikely to survive and hatch

  33. Spread of Avian Influenza Viruses among Birds • Certain birds, particularly water birds, act as hosts for influenza viruses by carrying the virus in their intestines and shedding it • Infected birds shed virus in saliva, nasal secretions, and feces • Susceptible birds can become infected with avian influenza virus when they have contact with contaminated nasal, respiratory, or fecal material from infected birds • Fecal-to-oral transmission is the most common mode of spread between birds

  34. Transmission of avian influenza virus to people 􀂃 Most human cases from close contact with infected poultry (chickens, turkeys) 􀂃 OR contact with surfaces or materials contaminated with the virus 􀂃 No sustained person-person transmission 􀂃 Concern is if the virus mutates and can be transmitted person-person

  35. …Human Transmission • Previously considered non-pathogenic for humans • 1997, Hong Kong • 2003, the Netherlands • 2004-2005, SE Asia

  36. Environmental survival • Can last indefinitely at a temperature dozens of degrees below freezing, as is found in the northern most areas that migratory birds frequent • Over 30 days at 0°C (32.0°F) (over one month at freezing temperature) • 6 days at 37°C (98.6°F) (one week at human body temperature) • decades in permanently frozen lakes • on hard non-porous surface such as plastic or stainless steel for 24-48 hours • on clothes, paper and tissues for 8-12 hours

  37. Heat… inactivates the virus • While cooking poultry to 70°C (158°F) kills the H5N1 virus, it is recommended to cook meat to 165°F to kill all foodborne pathogens • Inactivation of the virus also occurs under the following conditions: • 30 minutes 60°C (140.0°F) (half hour at a temperature that causes first and second degree burns in humans in ten seconds • AcidicpH conditions • Presence of oxidizing agents such as sodium dodecyl sulfate, lipid solvents, and B-propiolactone • Exposure to disinfectants: formalin, iodine compounds • Ordinary levels of chlorine in tap water kill H5N1 in public water systems

  38. ….inactivates the virus • Sunlight • Most detergents or disinfectants (bleach) • But is stable in environment when in pond or lake water and feces 􀂃 4 days at 71.6º F, 30 days at 32º F 􀂃 >1 month in feces at cool temperatures

  39. Problem If a new subtype of influenza A virus is introduced into the human population, most people have little or no protection against the new virus, and if the Virus can spread easily from person to person, a PANDEMIC (worldwide spread) may occur

  40. Birds with avian flu People with the flu + Sick Pig with both Strands of Influenza

  41. Attack of the Cell

  42. …………..attack of the Cell •A virion attaches to the host cell membrane via HA and enters the cytoplasm by receptor-mediated endocytosis, • A cellular trypsin-like enzyme cleaves HA into products HA1 and HA2 which promotes fusion of the virus envelope and the endosome membranes • In the nucleus, the viral polymerase complexes transcribe and replicate the v RNAs. • Newly synthesized mRNAs migrate to cytoplasm where they are translated. • The newly formed nucleocapsids migrate into the cytoplasm and eventually interact with a region of the cell membrane • NA destroys the sialic acid moiety of cellular receptors, releasing the progeny virions.

  43. Clinical Signs • Incubation period: 3-14 days • Birds - dead prior to observance of any clinical signs • Drop in egg production • Neurological signs - reduction in normal vocalizations • Depression (drop in egg production) anorexia, ruffled feathers • Combs swollen, cyanotic • Conjunctivitis and respiratory signs (coughing, sneezing and nasal discharge)

  44. Bird flu in Birds

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