Emerging Infectious Diseases: A Threat to
Global Public Health and Economic Security
Duane J Gubler
Professor
S. Machado
EcoHealth, Kunming, 16 Oct, 2012
Signature Research Program in Emerging Infectious Diseases
Duke-NUS Graduate Medical School, Singapore
Emerging Infectious Diseases: A Threat to
Global Public Health and Economic Security
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Background
Snapshot of recent epidemics
Reasons for emergence and spread
Prospects for the future
Challenges to reverse the trends
The Global Threat of Infectious Diseases
Emerging and re-emerging diseases
A/H1N1
Dengue
A/H1N1
Chikungunya
Dengue
Adapted from Morens, Folkers, Fauci 2004 Nature 430; 242-9
Emerging diseases
Re-emerging diseases
Major Infectious Disease Epidemics since 1980
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Dengue/DHF-1970s, SE Asia, global
HIV/AIDS-1980s-Africa,global
Drug resistant TB-1990s, US, global
Cholera-1991-Americas
Plague-1994-India, global
Foot & Mouth disease-1995,2000- Taiwan & UK
West Nile-1990s-Mediterranean, Americas
BSE-1990s- UK, Canada, US
Swine fever, 1996- Netherlands
H5N1 influenza-1997- HK-global
Nipah encephalitis-1998-Malaysia,Asia
SARS-2002- Asia, global
Chikungunya-2004-Africa, Asia
H1N1 influenza-2009-Mexico?,global
What did these Epidemic Infectious
Diseases have in Common?
• All were caused by zoonotic pathogens
• All spread by modern transportation
• Most had Asian origin
• Laboratory and clinical diagnoses were problematic
• Poor communication among countries
• Major economic impact
Major Infectious Disease Epidemics since 1980
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Dengue/DHF-1970s, SE Asia, global
HIV/AIDS-1980s-Africa,global
Drug resistant TB-1990s, US, global
Cholera-1991-Americas
Plague-1994-India, global
Foot & Mouth disease-1995,2000- Taiwan & UK
West Nile-1990s-Mediterranean, Americas
BSE-1990s- UK, Canada, US
Swine fever, 1996- Netherlands
H5N1 influenza-1997- HK-global
Nipah encephalitis-1998-Malaysia,Asia
SARS-2002- Asia, global
Chikungunya-2004-Africa, Asia
H1N1 influenza-2009-Mexico?,global
Plague Pandemics
• Justinian’s Plague (mid-6th Century A.D.)
• Black Death (mid-14th Century A.D.)
• Modern Pandemic (1894 – mid-1900s)
Global Distribution of Plague
Countries reporting plague, 1970-2000
Probable Sylvatic foci
Compiled from WHO, CDC, and country sources
Surat
Potential Spread of
Pnuemonic Plague
out of India, 1994
India
Delhi
Calcutta
Madras
Bombay
Pneumonic Plague in India
• Indian outbreak was a
major surprise – no plague
confirmed in India since
1966
• Clinical and lab diagnosis
• Media and panic driven
epidemic
• First epidemic to impact
global air transportation
• Caused huge economic
loss for India (> $3 billion)
Microbial Threats to Health
Chain of transmission among guests at Hotel M—Hong Kong, 2003
2 family
members
2 close contacts
4 family
members
Guangdong
Province,
China
4 HCWs*
Hospital 2
Hong Kong
F
A
A
F
156 close
contacts
of HCWs
and
patients
Hospital 3
Hong Kong
H
Hospital 1
HK
J
B
C
28 HCWs
4 other
Hong Kong
Hospitals
Vietnam
B
D
HCW
HCW
United
States
M§
D
E
Singapor
e
HCW
34 HCWs
Bangkok
Data as of 3/28/03
I
Germany
0 HCWs
Hospital 4
Hong Kong
Ireland
L§
E
C
B
K†
I
Hotel M
Hong
Kong
J
99 HCWs
(includes 17
medical students)
K†
A
H
Canada
G†
G†
3 HCWs
10 HCWs
37 HCWs
37 close contacts
HCW
2 family
members
Unknown
number close
contacts
* Health-care workers; † All guests except G and K stayed on the 9 th floor of the hotel. Guest G
stayed on the 14th floor, and Guest K stayed on the 11th floor; § Guests L and M (spouses) were not
at Hotel M during the same time as index Guest A but were at the hotel during the same times as
Guests G, H, and I, who were ill during this period.
Global SARS Cases (Probable)
WHO 26 September 2003
Country
Cases
Deaths
Case fatality
Canada
251
43
15.3%
China
5327
349
6.5%
Hong Kong
1755
299
16.9%
Singapore
238
33
15.5%
Taiwan
346
37
12.5%
Thailand
9
2
22%
U.S.
75
0
0%
Vietnam
63
5
7.9%
Other
81
5
6.2%
Total
8098
774
9.6%
Economic Impact of Selected Infectious Diseases
Plague, India
$5-6 bn
Why Have we Seen Such a Dramatic
Increase in Epidemic Infectious Diseases?
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Complacency, Lack of Political Will
Policy Changes
Changes in Public Health
Changing Life Styles/Behavior
Microbial Adaptation
Technology
Intent to Harm
Climate Change
Why Have we Seen Such a Dramatic
Increase in Epidemic Infectious Diseases?
Major Drivers
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Demographic Changes (Pop Growth)
 Environmental Change
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Uncontrolled Urbanization
Agricultural/Land Use Practices
Deforestation
 Animal Husbandry
Modern Transportation (Globalization)
 Increased Movement of People, Animals,
Commodities
Lack of Public Health Infrastructure
Urban Growth in Asian(1) and American(2) Cities, 1950-2010
13
12.4
12
11
10
Millons of People
9
7.8
8
7
6
5.2
4.7
5
4
3
2
1.2
1.3
1
0
1950
1.
2.
1980
2010
Mean population of Dhaka, Bangkok, Jakarta, Manila and Saigon.
Mean population of Rio de Janeiro, Sao Paulo, San Juan, Caracas
and Guayaquil.
The global air network
Average annual number of global airline
passengers by decade, 1950-2010
2000
1800
Million of Passenger (Mil)
1600
1400
1200
1000
800
600
400
200
0
1950-1960
IATA 2010
1970-1980
1980-1990
Decade
1990-2000
2000-2009
Commercial Air Traffic Over a 24 Hour Period
Global distribution of dengue virus serotypes, 1970
DEN 1
DEN 2
DEN 1
DEN 2
DEN 3
DEN 4
Gubler, 1998
DEN 1
DEN 2
Global distribution of dengue virus serotypes,
1970-2000
1981
1977
1980
1979
1981
1994
1982
1985
1975
1971
DENV – 1; DENV – 2; DENV – 3; DENV – 4
Global distribution of dengue virus serotypes, 2012
DEN 1
DEN 2
DEN 3
DEN 4
DEN 1
DEN 2
DEN 3
DEN 4
DEN 1
DEN 2
DEN 3
DEN 1
DEN 2
DEN 3
DEN 4
DEN 1
DEN 2
DEN 3
DEN 4
DEN 1
DEN 2
DEN 3
DEN 4
Adapted from Gubler, 1998
DEN 1
DEN 2
DEN 3
DEN 4
DEN 1
DEN 2
DEN 3
DEN 4
DEN 1
DEN 2
DEN 3
DEN 4
Exotic Infectious Diseases That Have
Recently Been Introduced to the US
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West Nile Fever
Dengue Fever
Yellow Fever
Mayaro Fever
Chikungunya
Epidemic
Polyarthritis
• SARS
• Influenza
• Lassa Fever
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Monkeypox
CJD/BSE
HIV/AIDS
Cholera
E. coli O157
E. Coli 0104:H4
Malaria
Leishmaniasis
Chagas Disease
Cyclospora
Live Animal Importation into the USA - 2002
• 47,000 mammals
 28 species of rodents
• 379,000 birds
• 2 million reptiles
& Poisonous snakes
• 49 million amphibians
• 223 million fish
Data from U.S. Fish & Wildlife Service
Exotic Mosquito Species Recently
Introduced and Established in the US
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Aedes (Stegomyia) albopictus
Ochlerotatus (Aedes Finlaya) togoi
Ochlerotatus (Aedes Finlaya)
japonicus
Aedes bahamensis
Culex biscayensis
Global Threat of Epidemic Infectious Diseases
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Disease and Trade-interwoven History
 14th century, Europe discovers exotic goods from
Asia
Global Trade Flourishes
 18th, 19, 20th centuries
New Millennium
 Integrated global economic system with a
transnational flow of knowledge, capital, products,
people, animals, and pathogens
 Rapid spread of epidemic infectious disease from
point of origin
Demographic Changes
Global
climate
change
Technology/Globalization
Socio-cultural organization
Urbanization
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M
A
N
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C
O
S
Y
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T
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M
Agricultural, land use
and animal husbandry
changes/practices
Habitat
alteration
REGIONAL ENVIRONMENTAL CHANGE
Species’ Ecological-evolutionary Dynamics
Opportunistic habitat expansion/ecological release
Vector (domestication)
Wildlife/reservoir transport/encroachment
Vector/reservoir species
Human encroachment
Host-Pathogen Dynamics
Emergence Processes of ‘Host-Parasite Biology’
Host switching (host novelty) • Breaching of pathogen persistence thresholds
Transmission amplification and genetic change (pathogen novelty)
Disease Emergence
ecosystem continuum
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S
Y
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The Global Threat of Epidemic
Infectious Diseases
Projected Global Trends
• Asian countries will lead in economic growth
• Asian Cities will lead in population growth
 Circular rural to urban migration
• Increased globalization
 Increased trade
 Increased movement of people, animals and commodities
 Increased movement of pathogens
• Increased probability of epidemic disease
• Increased threat to global economic security
Tuesday, Oct 16, 2012 http://www.dailymail.co.uk/science
The Armageddon virus: Why experts fear a
disease that leaps from animals to humans
could devastate mankind in the next five years
•Warning comes after man died from a Sars-like virus that had
previously only been seen in bats
•Earlier this month a man from Glasgow died from a tick-borne
disease that is widespread in domestic and wild animals in
Africa and Asia
Pathogens of Tomorrow
From Whence They Will Come?
From Asia
From Animals
Mostly Viruses
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Global Threat of Epidemic Infectious Diseases
Challenge to Reverse the Trend
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Prevent movement of pathogens and vectors via modern
transportation
Improve international cooperation and data sharing
Improve effective laboratory-based surveillance
Rebuild public health infrastructure to prevent & control
vector-borne and zoonotic diseases
 Trained personnel
 Laboratory and epidemiologic capacity
 Tools (vaccines, drugs, insecticides, mosquito control, etc)
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 Understanding disease ecology
Political will
 Economic support
 Regional prevention and control programs