emerging infectious diseases: a threat to global public health and economic security
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S. Machado
Emerging Infectious Diseases: A Threat to Global Public Health and Economic Security
Duane J Gubler Professor
Signature Research Program in Emerging Infectious Diseases Duke-NUS Graduate Medical School, Singapore
EcoHealth, Kunming, 16 Oct, 2012
Emerging Infectious Diseases: A Threat to Global Public Health and Economic Security
• 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
Adapted from Morens, Folkers, Fauci 2004 Nature 430; 242-9
Emerging diseasesRe-emerging diseases
Chikungunya
Dengue
Dengue
A/H1N1
A/H1N1
Major Infectious Disease Epidemics since 1980
• 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
• 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
MadrasBombay
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
Guangdong
Province, ChinaA
A
Hotel MHong Kong
B
J
H
Hospital 2
Hong Kong A
H
J
B
4 other Hong Kong
Hospitals
CD
E
Hospital 3 Hong Kong
Hospital 1 HK
Hospital 4 Hong Kong 2 family
members
C D E
34 HCWs
HCW
B Germany
Bangkok
Singapore
United States
I
IL§
M§
Vietnam
K † Ireland
K †
37 HCWs
HCW
0 HCWs
28 HCWs
156 close
contacts of HCWs
and patients
FG †
Canada
G †
F
4 family
members
10 HCWs
37 close contacts
99 HCWs (includes 17
medical students)
4 HCWs*
3 HCWs
HCW
HCW
2 family
members
Unknown number
close contacts
2 close contacts
* Health-care workers; † All guests except G and K stayed on the 9th 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.
Chain of transmission among guests at Hotel M—Hong Kong, 2003
Data as of 3/28/03
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?
• 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?
• Demographic Changes (Pop Growth) Environmental Change
- Uncontrolled Urbanization
- Agricultural/Land Use Practices
- Deforestation
Animal Husbandry
• Modern Transportation (Globalization) Increased Movement of People, Animals,
Commodities
• Lack of Public Health Infrastructure
Major Drivers
Urban Growth in Asian(1) and American(2) Cities, 1950-2010
1. Mean population of Dhaka, Bangkok, Jakarta, Manila and Saigon.
2. Mean population of Rio de Janeiro, Sao Paulo, San Juan, Caracas and Guayaquil.
The global air networkThe global air network
Average annual number of global airline passengers by decade, 1950-2010
IATA 2010IATA 2010
Mill
ion
of P
ass
enge
r (M
il)M
illio
n o
f Pa
ssen
ger
(Mil)
DecadeDecade
Commercial Air Traffic Over a 24 Hour Period
Global distribution of dengue virus serotypes, 1970Global distribution of dengue virus serotypes, 1970
Gubler, 1998
Global distribution of dengue virus serotypes, Global distribution of dengue virus serotypes, 1970-20001970-2000
1971
1975
1981
DENV – 1; DENV – 2; DENV – 3; DENV – 4
1985
1981
1994
1982
1980
1977
1979
Global distribution of dengue virus serotypes, 2012Global distribution of dengue virus serotypes, 2012
Adapted from Gubler, 1998
Exotic Infectious Diseases That HaveRecently Been Introduced to the US
• West Nile Fever• Dengue Fever• Yellow Fever• Mayaro Fever• Chikungunya• Epidemic Polyarthritis• SARS• Influenza• Lassa Fever
• 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
• Aedes (Stegomyia) albopictus
• Ochlerotatus (Aedes Finlaya) togoi
• Ochlerotatus (Aedes Finlaya) japonicus
• Aedes bahamensis
• Culex biscayensis
Global Threat of Epidemic Infectious Diseases
• 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
Urbanization Agricultural, land use and animal husbandry
changes/practices
Habitat alteration
Species’ Ecological-evolutionary DynamicsOpportunistic habitat expansion/ecological release
Vector (domestication) Vector/reservoir species Wildlife/reservoir transport/encroachment Human encroachment
Host-Pathogen DynamicsEmergence Processes of ‘Host-Parasite Biology’
Host switching (host novelty) • Breaching of pathogen persistence thresholdsTransmission amplification and genetic change (pathogen novelty)
Disease Emergenceecosystem continuum
HUMAN
ECOSYSTEM
NATURAL
ECOSYSTEM
Global climate change
Demographic ChangesTechnology/Globalization
Socio-cultural organization
REGIONAL ENVIRONMENTAL CHANGE
The Global Threat of Epidemic Infectious Diseases
• 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
Projected Global Trends
Tuesday, Oct 16, 2012
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
http://www.dailymail.co.uk/science
Pathogens of Tomorrow
From Whence They Will Come?
From Asia
From Animals
Mostly Viruses
35
Global Threat of Epidemic Infectious Diseases
Challenge to Reverse the Trend
• 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)
Understanding disease ecology
• Political will
Economic support
Regional prevention and control programs
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