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Emerging Infections

Emerging Infections. Angela McLean Institute for Emergent Infections of Humans James Martin 21 st Century School Zoology Department Oxford University. Definition: Emerging infections. More cases of an old infection (eg TB is re-emerging)

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Emerging Infections

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  1. Emerging Infections Angela McLean Institute for Emergent Infections of Humans James Martin 21st Century School Zoology Department Oxford University

  2. Definition: Emerging infections • More cases of an old infection (eg TB is re-emerging) • Newly discovered / detected (eg Helicobacter pylori has been around for ages, but only recognised in the last couple of decades) • Genuinely new • SARS • HIV • BSE • H5N1 flu

  3. 20th Century Adult Mortality Rates in the UK Males Females Deaths per million population

  4. Causes of death in Chile1909 and 1999 Weiss & McMichael 2006

  5. Life expectancy at birth: 8 countries 1950 - 2005 Weiss & McMichael 2006

  6. Joseph Bazalgette Significant events in public health

  7. 25 years of HIV/AIDS

  8. Emerging and re-emerging infectious diseases: 1996 - 2004

  9. Monthly summary of EID events

  10. EID events December 2007 Influenza H5N1 China, Egypt Indonesia, Myanmar Pakistan, Vietnam, UK CJD UK Brucellosis China Coccidiodo mycosis USA Rift Valley Fever Sudan Undiagnosed neurological illness USA Chikungunya Indonesia Psittacosis Netherlands, Brazil, USA Ebola Haemorrhagic Fever Uganda Trypanosomiasis, foodborne Venezuela Plague Uganda

  11. Three Big Questions • What’s out there? • In humans already • Known in animals • Unknown • Which are likely to trouble humans? • Making new contacts with new infectious agents • What are species barriers • Understanding pathogenesis • How do pathogens adapt to humans? • If they do, could we control them? • Establishing good surveillance • Making drugs and vaccine • Understanding speed of spread • Calculating minimum or optimal interventions

  12. What is out there? • In humans already • How should we deal with known infections of humans (eg HIV, TB, malaria, dengue, MRSA… • Known in animals • How do we plan for the emergence of novel infections that we know, expect, and cannot prevent – influenza • Unknown • What can we do that is cautious and proportionate about unknown infections that may emerge in the future?

  13. Which are likely to trouble us?Environmental change • New situations for human contact with novel agents • Bushmeat • xenotransplantation • Better situations for the spread of novel agents that have crossed into humans • increased sexual contact for HIV • rapid international travel for SARS • Environmental change affecting vectors

  14. Which are likely to trouble us?Genetic change • Mostly we can just classify, but after the fact • We dream of being able to predict sequence change that would enable cross-species transmissions • Even for influenza, the determinants of what strain will emerge next are not understood • We are remarkably ignorant about why some infections make us sick and others are without symptoms

  15. Will we be able to control future threats? • Developing good surveillance • New drugs and vaccines • Understanding how fast infections spread and evolve • Calculating sufficient interventions to control spread or the likely impact of the best we can manage

  16. Three Big Questions • What’s out there? • In humans already • Known in animals • Unknown • Which are likely to trouble humans? • Making new contacts with new infectious agents • What are species barriers • Understanding pathogenesis • How do pathogens adapt to humans? • If they do, could we control them? • Developing good surveillance • Making drugs and vaccine • Understanding speed of spread • Calculating minimum or optimal interventions

  17. Further Reading • 6 pages • Weiss & McMichael (2004) Social and Environmental risk factors in the emergence of infectious diseases Nature Medicine vol 10 pp S70-s76 • ~ 40 pages • The world health report 2007 - A safer future: global public health security in the 21st century http://www.who.int/whr/2007/en/ • ~ 750 pages • Laurie Garrett (1996) The Coming Plague: Newly Emerging Diseases in a World Out of Balance

  18. Which viruses will we work on? • HIV • Dengue • Hepatitis C Virus • Influenza

  19. 7 Tobacco HIV HBV + HCV 6 Non-HIV TB Measles RSV, Rota Flu Dengue 5 Accidents HPV Suicide 4 West Nile 3 SARS Ebola Polio vCJD Hanta 2 Log10 Why those four? Estimated deaths from viral infections 2003

  20. Why study adaptation to humans? • 3 steps to emergence • New transmission to humans • Some transmission amongst humans • Adaptation to become an efficient pathogen of humans • Evidence that step 1 is not highly unusual • H5N1 – currently few clusters • Simian Foamy Virus in zoo keepers • SARS immunity in Hong Kong wet market workers

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