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Avian Influenza

Avian Influenza. Credit: WHO Viet Nam. Human influenza. Major signs and symptoms Fever, cough, sore throat, headache, malaise, anorexia, photophobia, joint and muscle pains Respiratory signs may occur but not always present Severe or fatal disease Elderly, particularly over 65 years of age

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Avian Influenza

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  1. Avian Influenza Credit: WHO Viet Nam

  2. Human influenza • Major signs and symptoms • Fever, cough, sore throat, headache, malaise, anorexia, photophobia, joint and muscle pains • Respiratory signs may occur but not always present • Severe or fatal disease • Elderly, particularly over 65 years of age • Chronic broncho-pulmonary disease • Infants and young children • Other chronic diseases, e.g. diabetes

  3. Influenza pandemics 20th century Credit: US National Museum of Health and Medicine 1918: “Spanish Flu” 1957: “Asian Flu” 1968: “Hong Kong Flu” 20-40 million deaths 1-4 million deaths 1-4 million deaths A(H1N1) A(H2N2) A(H3N2)

  4. Three types A, B, C Surface antigens H (haemaglutinin) N (neuraminidase) Influenza A has subtypes H3N2, H1N1 (common human) H7N7 (avian 2003, The Netherlands) H5N2 (avian vaccine) H9N2 (human case in Hong Kong, SAR China, 2003) H5N1 (current avian strain of concern) Influenza virus Credit: L. Stammard, 1995

  5. Domestic birds From birds to humans Migratory water birds • Hong Kong, SAR China 1997, H5N1 • Hong Kong, SAR China 1999, H9N2 • The Netherlands 2003, H7N7 • Hong Kong, SAR China 2003, H5N1 Source: WHO/WPRO

  6. Definitions • Epidemic – a located cluster of cases • Pandemic – worldwide epidemic • Antigenic drift • Changes in proteins by genetic point mutation & selection • Ongoing and basis for change in vaccine each year • Antigenic shift • Changes in proteins through genetic reassortment • Produces different viruses not covered by annual vaccine

  7. Reassortment (in humans) Migratory water birds Source: WHO/WPRO

  8. Reassortment (in pigs) Migratory water birds Source: WHO/WPRO

  9. Migratory water birds Mutation (in humans) Source: WHO/WPRO

  10. Avian Influenza Current situation

  11. A(H5N1) chronology Thailand – reporting “chicken cholera” 12/12: Rep. of Korea – avian flu 08/1: Viet Nam – avian flu 12/1: Viet Nam – 3 human avian flu deaths confirmed 12/1: Japan – avian flu 23/1: Thailand – avian flu 23/1: Thailand – 2 human avian flu cases confirmed 27/1: Laos PDR – avian flu (H5) 27/1: China – avian flu 02/2: Indonesia – avian flu 17/3: Thailand and Viet Nam – Total: 34 cases with 23 deaths Nov Dec Jan Feb Mar 04

  12. Why are we concerned? • Increasing number of • Countries/areas with avian influenza • Human avian influenza cases • Co-circulating human & avian influenza viruses • High risk of genetic reassortment • Emergence of pandemic strain • Majority of human population would lack immunity

  13. Avian Influenza WHO strategy

  14. WHO strategy • Risk reduction (avoid emergence of a new virus) • Elimination of animal reservoir (FAO, OIE) • Culling, movement control, vaccine • Protection and immunization of at-risk individuals • Cullers, healthcare personnel • Strengthen surveillance • Animals (FAO and OIE) • Humans • Diagnostic tests, national detection, global reporting • Improve pandemic preparedness • A(H5N1) vaccine development • Access to antiviral drugs • Pandemic plan & self-assessment (national and international)

  15. WHO partnership • Global Influenza Laboratory Network • Global surveillance (human and animal) • Development of vaccine strains • Development of reagents for influenza diagnostic testing • Antiviral drug susceptibility testing

  16. WHO partnership • Global Outbreak Alert & Response Network (GOARN) • Technical partnership, coordinated by WHO, to provide rapid multi-disciplinary support for outbreak response • Field teams • Viet Nam, Thailand, Cambodia, China, Indonesia • Technical support • CDC, GEIS - USA; NIID - Japan; HPA - UK; EPIET, EC - EU; NCEPH, FETP - Australia; Institut Pasteur, Epicentre, InVS - France; Health Canada - Canada; RIVM - The Netherlands; WHO HQ/RO/CO

  17. WHO support to countries • Technical guidelines (web site) • Specimen collection; laboratory diagnosis; biosafety; surveillance; clinical management; pandemic preparedness; vaccination • Country support • Laboratory strengthening; case identification; patient management; infection control • Research coordination; support for safe culling; personal protective equipment • Intersectoral collaboration (health, agriculture) • Resource mobilisation • Funding framework • Vaccine donations

  18. Avian Influenza Public health tools

  19. Tools for disease control • Public health surveillance • Epidemiological studies • Clinical studies • Laboratory testing • Vaccine and antivirals • Pandemic preparedness planning • Communications • Public health interventions

  20. Tools for disease control • Public health surveillance • Epidemiological studies • Clinical studies • Laboratory testing • Vaccine and antivirals • Pandemic preparedness planning • Communications • Public health interventions Public health surveillance and epidemiological, clinical and laboratory studies are complementary

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