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Lessons learnt from smallpox eradication and post-eradication strategy

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Presentation made during the international meeting titled “Maintaining global freedom from rinderpest” held in FAO-HQ from 20 to 22 January 2016. © FAO: http://www.fao.org

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Lessons learnt from smallpox eradication and post-eradication strategy

  1. 1. Dr. David Ulaeto © Crown copyright 2014 Dstl 26 February 2016 Lessons learnt from smallpox eradication and post-eradication strategy
  2. 2. Outline • Variola virus and orthopoxviruses • Smallpox and its eradication • Sequestration of variola virus after eradication • Regulation of variola virus repositories & research • Emergence of related viruses 26 February 2016 ©Dstl 2016
  3. 3. Genus Orthopoxvirus • Members: variola (smallpox), monkeypox, cowpox, vaccinia, ectromelia, raccoonpox, taterapox, camelpox, rabbitpox, buffalopox • All are morphologically identical • All are immunologically related and confer protection against other members of the genus 26 February 2016 ©Dstl 2016
  4. 4. Why Was Smallpox Eradication Possible? • No animal reservoir • No latent or persistent infection • Smallpox was an easily recognised disease • The vaccine was effective against all strains of virus • Vaccine properties. Efficacy, potency, low cost, abundance, heat stability, easy administration • WHO determination 26 February 2016 ©Dstl 2016
  5. 5. Smallpox Control 26 February 2016 Lady Mary Wortley Montagu Variolation 1721 Edward Jenner Vaccination 1796 ©Dstl 2016
  6. 6. Smallpox Eradication • 1721. Variolation • 1796. Vaccination • 1801. Eradication predicted • 19th century. Vaccination spreads throughout the world • 1950. Freeze dried vaccine developed 26 February 2016 ©Dstl 2016
  7. 7. Smallpox Eradication • 1959. WHO adopts Russian proposal to eradicate smallpox • 1967. Intensified eradication campaign begins • 1975. Last case in India • 1977. Last case in Somalia – last endemic case in the world • 1978. Last case in the world – Birmingham, UK • 1980. Eradication certified by WHO • 1993. Genome of variola virus sequenced • ???? Last stocks of variola virus to be destroyed 26 February 2016 ©Dstl 2016
  8. 8. Sequestration of Variola Virus After Smallpox Eradication • WHO writes to all governments • WHO writes to all Virus laboratories • WHO scans index medicus for variola research – Writes to directors • WHO requests destruction or transfer of all stocks 26 February 2016 ©Dstl 2016
  9. 9. Sequestration of Variola Virus After Smallpox Eradication • In 1975, 75 laboratories held variola virus stocks 26 February 2016 Year No of Laboratories 1975 75 1977 18 1978 13 1979 7 1980 6 1981 4 1982 3 1983 2 ©Dstl 2016
  10. 10. Sequestration of Variola Virus After Smallpox Eradication • Forgotten stocks have been discovered on at least 4 occasions 26 February 2016 Year No of Laboratories 1979 USA 1979 Tanzania 1985 UK 2014 USA ©Dstl 2016
  11. 11. Sequestration of Variola Virus After Smallpox Eradication • Centralised in 2 locations: – CDC, Atlanta, USA – Vector, Novosobirsk, Russia • Maximum security lab’s • Biennial inspection by WHO • All work with live variola virus requires prior approval by WHO 26 February 2016 ©Dstl 2016
  12. 12. Why Retain Variola Virus After Smallpox Eradication? • Smallpox is a human disease * • Treatment requires anti-virals * – Brincidofovir – Tecovirimat • The vaccine has significant side-effects * – A safer vaccine is required • Modern diagnostics • * These rationales do not apply to rinderpest 26 February 2016 ©Dstl 2016
  13. 13. Emergence of Related Viruses • Monkeypox – Human infection only apparent since 1970 • Clinically similar to smallpox • Virus closely related to variola • Controlled by smallpox vaccine 26 February 2016 ©Dstl 2016
  14. 14. Emergence of Related Viruses: The Human Niche 26 February 2016 Smallpox Vaccine Empty Monkeypox? • Smallpox eradication opened an ecological niche ©Dstl 2016
  15. 15. Why is this important? • Eradication – leads to loss of herd immunity – Vulnerability to deliberate or accidental release 26 February 2016 ©Dstl 2016
  16. 16. Summary • Identification of laboratories and stocks is essential • Oversight of handling laboratories is essential – Accidental releases have occurred – Birmingham 1978 – after last endemic case • Emergence of related viruses – e.g. monkeypox • Bioterrorism/accident – The virus could be recreated – All research with virus must be regulated • Diagnostics/surveillance – Subject to changing technology – Need to define requirements 26 February 2016 ©Dstl 2016
  17. 17. Questions? 26 February 2016 ©Dstl 2016
  18. 18. Questions? 26 February 2016 ©Dstl 2016

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