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