Avian influenza, pandemic influenza,
ecohealth
A/Prof Colin D Butler
National Centre for Epidemiology and
International Association for Population Health,
Ecology and Health, Dr Delia Grace
Kunming, October, 2012 ILRI

Two views of Zoonotic Emerging
Infectious Diseases (ZEIDS)
• ZEIDs have been and continue to be one
of the most important issues in EH
• ZEIDs are less important than neglected
tropical zoonoses and divert resources
from tackling them
• Both views focus on the microbe rather
than the milieu
2

Warning! Contrarian views ahead
• H5N1 very unlikely to become a global
pandemic
• H5N1 very unlikely to establish in SSA
• Current EH side-stepping problems crucial
to our health and future
– Creation of continental-wide pathogenic milieus
– Difficult problems of equity and justice
3

Could H5N1 HPAI become the next
“mother of all pandemics”?
4

Margaret Chan: “three global crises .. on horizon” ..
Climate change
regional food shortages and soaring food prices
pandemic influenza
CGIAR report:
SARS: $50 - 100 billion
“major avian influenza pandemic “ > $1 trillion (Burns et al.
2008). $2 trillion (World Bank 2008).
5

Claude Bernard (1813-1878)
milieu and microbe
6

“Pathogenic tradeoff”
Pathogens “want” to reproduce
Effect on host not of concern:
Sometimes 1. hurt, don’t kill pathogen
2. don’t hurt reproduction
chance
3. kill slowly enhanced
4. kill quickly
4. In comparison,
reproduction harder
trend to co-existence
Ewald P (2004). Evolution of virulence. Infectious Disease Clinics of
North America 18:1–15.
7

New milieus: different tradeoff?
pathogens in crowded host milieus that kill quickly have
- numerous other hosts to colonise
- hosts have high genetic similarity
- Immuno-suppressors and depressors
- LITTLE or No evolutionary penalty from rapid host
mortality
10,000 BCE -Neolithic transition: measles, smallpox, diptheria
1500-1600 - Americas: disease destroyed civilisation
1800s – Europe – industrialisation, urbanisation: White Plague
1900s – Africa – colonialisation, urbanisation: HIV, AIDS
8

Milieu and the
Adapted from Oxford et al Lancet Inf Diseases 2002; 2:111-4
2.5% global mortality (with bacterial co-infections)
9

Reasons to be sceptical of H5N1 pandemic
1. More capacity to manage:
• Rapid global response (e.g. SARS)
• Numerous antibiotics for secondary bacterial infections
• Flu vaccines + anti-viral antibiotics
2. H5N1 case fatality rate questioned (Palese & Wang)
• If H5N1 develops human Ro >1 human lethality may fall (Ewald)
3. 1918 epidemic very atypical (c500 years human flu
epidemics)
• 1918 milieu extraordinary, unlikely to be coincidental
• Current milieu favours evolution of HPAI, but not HPHI
4. Vested interests exaggerate risk of H5N1 as human
pandemic
10

Could H5N1 HPAI establish in Sub
Saharan Africa?
Costard et al., RVC
11

HPAI would not have
established – even in the
absence of any control (Bett
et al., 2012 TED)
• HPAI in Nigeria: Epidemic occurred
between Dec 2007 – Jul 2008
Boostrap distribution
• Phylogenetic analysis shows the virus
clustered in sub-lineages I, II. III and IV,
indicating re-introductions (Fusaro et al.,
2009)
• Theory of re-introduction supported by
low R0 estimate : 0.7 – 1.1
• EID Surveillance – need to incorporate epi
info/risk factors
12

Most costs associated with control, not
disease
Nigeria
•140 million people
•150 million poultry – 25% intensive systems
HPAI
•I.3 million chicken died or culled One person died
•80% people stopped eating chicken for up to 4 mths
•41% of farm workers lost jobs
•Most compensation went to larger farms
•Dead chickens widely consumed, Sick chickens widely
consumed, Vaccination probably used
•Around 100 million USD lost or spent
13

From emerging microbe to pathogenic milieu
14

Land-ocean temperature: 1880-2011 Rainfall intensity : 1900-2011
Sea Level: 1993-2012 Arctic ice: 1979-2012
Million
Km 2
Earth system
observations
15

Oil price (US$ per
2005: Plateau Oil barrel)
Apparent production cap
Production
(million barrels/day)
Adapted from Murray & King, Nature. 2012; 481: 433-5.
1998 2000 2004 2008 2011 16

“IMF assessment of world recovery bleak”
October 9, 2012
17

Could civilisation failure “breed” a
megapandemic?
2012 20??
rapid public health response* public health breakdown
limited antimicrobial nutrition worse
resistance, but increasing living conditions worse
nutrition ok conflict increasing?
* For diseases perceived as major threats to
developed countries
18

conflict
Large-scale
population milieu for catastrophic
dislocation emerging diseases, e.g.
multi-drug –resistant TB,
artemisinin-resistant
failing malaria, HIV, others
governance
Sea level Impaired
rise public
(future) health
Rising food worse global
prices nutrition
High
Climate energy
Increased use
change costs
of crops for
fuel Butler, in press (2012)
Dependence on fossil fuel,
declining in quantity, quality
and accessibility

Less milieu for minor emerging
conflict diseases, chronic
diseases, diseases of
ageing
Improved
public health
Less
climate
Improved Better global education and
change
governance communication, slower
population growth, fairer
Stable food global society, new ways to
prices measure progress, new ways
of thinking,
less food waste, meat
consumption “contracts and
converges”
Clean abundant energy
technologies, especially solar
Butler, in press (2012)

Acknowledgements
6 “Di TRGIV: “Environment, agriculture and infectious
diseases of poverty”
Prof AJ McMichael (ANU)
WORLD BANK Prof Xiao-Nong Zhou (China CDC)
WHO Technical Report
Also Bianca Brijnath, Adrian Sleigh
Special Programme for Tropical
Diseases Research
21

Summary
• H5N1 very unlikely to become a global
pandemic
• H5N1 very unlikely to establish in SSA
• Current EH side-stepping problems crucial
to our health and future
– Creation of continental-wide pathogenic milieus
– Difficult problems of equity and justice
22

http://www.bodhi.net.au/html/forumforthefuture.html
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