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Role of Vaccine in control of Avian Influenza

Role of Vaccine in control of Avian Influenza. H. K. Pradhan High Security Animal Disease Laboratory , (A National Referral Facility ) Anand Nagar, Bhopal. WORLD SCENARIO. Important AI virus- H5, H7,H9 1997 outbreak -Hong Kong (H5N1)

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Role of Vaccine in control of Avian Influenza

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  1. Role of Vaccine in control of Avian Influenza H. K. Pradhan High Security Animal Disease Laboratory, (A National Referral Facility ) Anand Nagar, Bhopal

  2. WORLD SCENARIO • Important AI virus- H5, H7,H9 • 1997 outbreak -Hong Kong (H5N1) • 2003-2006 - 60 countries affected with H5N1 • Countries badly affected: Vietnam, Thailand, Indonesia, China Russia, Turkey, Romania • Human deaths – 141 Indonesia- 46, Vietnam- 42, Thailand-16, China-14

  3. SITUTATION IN INDIA • Till Jan, 2006- India was free from HPAI. • Since 2003- H9N2 have been detected. • First outbreak of H5N1 –February, 2006. • States affected- Maharastra, Gujarat and Madhya Pradesh. • Introduced through migratory birds. • Heavy mortality in chickens. • Culling of 1.14 million birds , destruction of 1.475 million eggs, 8600 MT feed. • Disease controlled.

  4. CONTROL STRATEGIES • Stamping out - within 3 Km zone . • Vaccination with effective monitoring. • Combination of stamping out and vaccination. • Countries effectively controlled AI-Republic of Korea, India. • Countries going for vaccination –Southern Russia, France, Holland (backyand, sanctuary), China.

  5. TYPES OF VACCINES • Inactivated Homologous vaccine (field strain) • Inactivated heterologus vaccine (same HA, different NA-DIVA), H5N2, H5N8, H5N9 • Recombinant live viral vector vaccines - Fowl pox, Adeno (HA gene insert). • Vaccines developed by reverse genetic (inactivated). • Recombinant H5 HA antigen using prokaryotes or baculo virus expression system. • DNA vaccine (H5 HA); • Peptide vaccine.

  6. ADVANTAGES OF VACCINATION • Protect against clinical sign and death. • Reduces shedding of virus. • Prevents contact transmission. • Protects against challenges with high dose of field virus. • Protects against changing virus . • Increases resistance to AI infection. • Reduces AIV replication. • Decreases the risk of human infection.

  7. DISADVANTAGES OF VACCINATION • Fear for mutation. • Silent spreading of virus • Difficult to differentiate between vaccinated and infected birds (serological)

  8. ISSUES NEED TO BE RESOLVED BEFORE VACCINATION • Choice of vaccine – homologous, heterologous. • Standardization of manufacturing practices • Proper storage, distribution,administration. • Adequate serological and virological studies. • Exit strategy to prevent permanent use. • Selective vaccination or mass vaccination.

  9. WHAT INDIA SHOULD DO • AI surveillance to continue. • Sampling should be adequate and proper. • Choice of dianostic methods. • If small areas are affected-culling is best. • If widespread outbreaks-vaccination to create immune zone. • Vaccination from periphey to central part. Cont……

  10. WHAT INDIA SHOULD DO • Panic selling should be avoided. • Strict biosafety measures. • Fear of genetic recombination (H5N1 and H9N2) • Grand parent stocks should be protected. • Vaccination of backyard poultry is important.

  11. CHOICE OF VACCINE • Heterologous inactivated vaccines, • Inactivated homolgous vaccine (H5N1) developed in India. • Recombinant fowl pox vaccine (from H5N8, H5N1). • Recombinant adeno virus vaccine.

  12. Stamping out and vaccination is ideal Thank You

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