Emerging, re-emerging and
epidemic prone
infectious diseases
World Health Organization
Definitions
• Emerging infectious diseases
newly identified or previously unknown
infections
• Re-emerging infectious diseases
re-appearance of, or increase in number
of, infections from a disease previously
known
Emerging Infectious Diseases:
Definition
Diseases of infectious origin whose incidence
in humans has increased within the recent
past or threatens to increase in the near
future,
including:
previously unknown infectious diseases;
known but appearing in new geographic areas;
or increase abruptly; and also those which
are re-emerging after a period of quiescence
(Source: WHO and Institute of Medicine Report 1992 for US).
Infectious Diseases
One-third of World Deaths
Total deaths (51.9 million)
Other causes 67%
(34.6 million)
Infectious diseases 33%
(17.3 million)
Infectious Diseases: A World in
Transition
AIDS
UP
Avian Influenza
Ebola
Marburg
Cholera
Rift Valley Fever
Typhoid
Tuberculosis
Leptospirosis
Malaria
Chikungunya
Dengue
JE
Antimicrobial resistance
?
DOWN
Guinea worm
Smallpox
Yaws
Poliomyelitis
Measles
Leprosy
Neonatal tetanus
World Health Organization
But we are in transition,
too...
World Health Organization
We’re not the people we used to be
• The human species continues to change
and to change its surroundings: the ways
we live, work, relax; the places we go; the
foods we eat ...
• The changing nature of our interactions
with each other and with our environment
alters the dynamics of disease
epidemiology and exposes us to new
threats.
Overcrowded,
ever growing
urban areas
Environmental
changes,
pollution,
Climate
change
Uncontrolled urbanisation
And many other factors ...
• international travel and commerce
• human demographics and behaviour
• technology and industry
• economic development and changes
in land use
• microbial adaptation and selection
ENVIRONMENT
Climate change
Mega-cities
Vector
proliferation
Migration
Pollution
Exploitation
Antibiotics
HUMAN
Food
production
ANIMALS
Intensive farming
Transmission
Population
Growth
Vector
resistance
VECTORS
Determinants of change
• Increased susceptibility
• Increased opportunity
• Rapid adaptation
Emerging and re-emerging
infectious diseases:
A new public health threat?
Emerging diseases are not
new to mankind ...
Old World Diseases transferred
to New World
• Smallpox
• Schistosomiasis
• Measles
• Typhus
• Yellow fever
• Influenza
• Malaria
• Leprosy
• Plague
Newly identified pathogens
(1973 - 1989)
1973
1975
1976
1977
1980
1981
1982
1983
1988
1989
Rotavirus
Parvovirus B19
Cryptosporidium parvum
Ebola virus, Legionella pneumophilia,
Hantaan virus, Campylobacter jejuni
HTLV-1
Staphylococcus toxin
E. coli O157, HTLV-2, Borrelia burgdoferi
HIV virus, Helicobacter pylori
HHV-6, Hepatitis E
Ehrlichia chaffeensis, Hepatitis C
Newly identified pathogens
(1990 - 1999)
1990
Guanarito virus
1991
Encephalitozzon hellem
1992
Vibrio cholerae O139
1992
Bartonella henselae
1993
Sabia virus
1995
Hepatitis G virus
1995
Human herpesvirus-8
1996
TSE causing agent (nvCJD)
1997
Avian influenza (Type A H5N1)
1999
Nipah virus, Avian Influenza H9N1,
Stealth viruses
Newly identified pathogens
(1997 - 2009)
• 1998 Nipah encephalitis
• 2003 SARS
• 2004 Avian influenza H5N1
• 2006 Chikungunya- re-emergence
• 2009 Pandemic influenza A H1N1
The microbial world is dynamic
….Emergence of pathogens continues ….
Since 1973
39 newly identified pathogens,
examples
1973
1977
1980
1983
1988
1992
1996
1999
2003
2009
Rotavirus
Ebola virus, Hantaan virus
HTLV-1
HIV virus H pylori
Hepatitis E
Vibrio cholerae O139
Avian influenza A (H5N1)
Nipah virus
SARS
Pandemic Influenza A
(H1N1)
Others reemerged
Dengue/DHF
Cholera
Malaria
Chikungunya
J. Encephalitis
Leptospirosis
N.meningitidis
Emerging Zoonoses: Ever increasing!
 Current estimates- 1,415
microbes are infectious for
human.
 Of these, 868 (61%) considered
zoonotic.
 70% of newly recognized
pathogens are zoonoses.
Source: NATURE; JULY 2004
www.nature.com/nature
Emerging Zoonoses: Human-animal
interface
Bats: Nipah virus
Avian influenza
virus
Deer tick (Ixodes
scapularis)
Marburg virus
Ebola
virus
Hantavirus Pulmonary Syndrome
Borrelia burgdorferi: Lyme
Mostomys rodent: Lassa fever
SARS: THE FIRST EMERGING
INFECTIOUS DISEASE OF THE 21ST
CENTURY
No infectious disease has spread so fast and far as SARS did in 2003
SARS Cases
19 February to 5 July 2003
Total: 8,439 cases, 812 deaths,
30 countries in 7-8 months
Europe:
10 countries (38)
Canada (243)
Russian Fed. (1)
Mongolia (9)
China (5326)
USA (72)
Kuwait (1)
India (3)
Colombia (1)
Hong Kong (1755)
Korea Rep. (3)
Macao (1)
Taiwan (698)
Malaysia (5)
Viet Nam (63)
Singapore (206)
Brazil (3)
Indonesia (2)
Philippines (14)
Thailand (9)
South Africa (1)
(
Australia (5)
New Zealand (1)
Source: www.who.int.csr/sars
Emergence of HPAI (H5N1)
2003-June 2008 a total of 385 cases with 243 deaths
Examples of recent emerging diseases
Source: NATURE; Vol 430; July 2004;
www.nature.com/nature
Risk factors for emerging zoonoses:
close human animal interface in Asia
Examples of recent emerging and reemerging diseases
vCJD
E. coli O157:H7
West Nile virus
Chikungunya
Monkeypox
SARS
Hantavirus
pulmonary
syndrome
Nipah
Ebola
Widespread or pandemic:
• MDR tuberculosis
• XDR tuberculosis
• Influenza A (H5N1) and (H7N7)
• MDR malaria
• Dengue
Hendravirus
Marburg
Rift Valley fever
Severe acute respiratory Syndrome (SARS)
Epidemic curve:
Geographic distribution of probable cases
Source: Nature 2004;430:242-249
Probable Cases 8096, Deaths 774
(CFR=9.6%)
(1 Nov 2002 to 31 July 2003)
26 Countries,
8098 cases, 774 deaths
Lesson learnt from SARS
•
An infectious disease in one country is a threat to all
•
Important role of air travel in international spread
•
Tremendous negative economic impact on trade, travel and
tourism, estimated loss of $ 30 to $150 billion
•
High level commitment is crucial for rapid containment
•
WHO can play a critical role in catalyzing international
cooperation and support
•
Global partnerships & rapid sharing
enhances preparedness and response
of
data/information
Highly Pathogenic Avian Influenza (H5N1)
•
Since Nov 2003, avian influenza H5N1 in birds have
affected 60 countries across Asia, Europe, MiddleEast & Africa
•
More than 220 million birds killed by the AI virus or
culled to prevent further spread and the number
keeps growing
•
A majority of human H5N1 infection was due to direct
contact with birds infected with the virus
•
As of 19 June 2008, a total of 385 human cases of
H5N1 were reported from 15 countries worldwide
with 243 deaths.
Distribution of Human Cases of Avian
Influenza, 2003-2008
Confirmed Human Cases of Avian
Influenza A/(H5N1) 01 Jul 2009
Country
2003
cases
2004
2005
2006
2007
2008
2009
Total
deaths cases deaths cases deaths cases deaths cases deaths cases deaths cases deaths cases deaths
Azerbaijan
0
0
0
0
0
0
8
5
0
0
0
0
0
0
8
5
Bangladesh
0
0
0
0
0
0
0
0
0
0
1
0
0
0
1
0
Cambodia
0
0
0
0
4
4
2
2
1
1
1
0
0
0
8
7
China
1
1
0
0
8
5
13
8
5
3
4
4
7
4
38
25
Djibouti
0
0
0
0
0
0
1
0
0
0
0
0
0
0
1
0
Egypt
0
0
0
0
0
0
18
10
25
9
8
4
30
4
81
27
Indonesia
0
0
0
0
20
13
55
45
42
37
24
20
0
0
141
115
Iraq
0
0
0
0
0
0
3
2
0
0
0
0
0
0
3
2
Lao People's
Democratic Republic
0
0
0
0
0
0
0
0
2
2
0
0
0
0
2
2
Myanmar
0
0
0
0
0
0
0
0
1
0
0
0
0
0
1
0
Nigeria
0
0
0
0
0
0
0
0
1
1
0
0
0
0
1
1
Pakistan
0
0
0
0
0
0
0
0
3
1
0
0
0
0
3
1
Thailand
0
0
17
12
5
2
3
3
0
0
0
0
0
0
25
17
Turkey
0
0
0
0
0
0
12
4
0
0
0
0
0
0
12
4
Viet Nam
3
3
29
20
61
19
0
0
8
5
6
5
4
4
111
56
Total
4
4
46
32
98
43
115
79
88
59
44
33
41
12
436
262
Japanese encephalitis (JE)
Clinical spectrum of Japanese encephalitis
Die
Severe
Moderate
Mild
Asymptomatic
For every case hospitalized, there are likely to be about 300 other people infected with JE, but with mild illness or no symptoms
Epidemiology and Lesson Learnt (JE)
Comprehensive
immunization program:
Japan, South Korea, Taiwan, China and Thailand
Program commenced but needs expansion or
development:
Sri Lanka, Vietnam, Malaysia, India (state-based)
Trial taken place and there are plans to
introduce a program:
Nepal
Confined to East Asia till first half of 20th Century
Spread to SE Asia in second half of 20th Century
Persistent since 1978 in SE Asia
Outbreaks of Hendra/Nipah virus infection,
1994-2007
Nadia, Kushtia & Thakurgaon,2007
Nipah outbreaks, Asia-Pacific Region, 1998-2008
Year/Month
Location
No. cases
No. deaths
CFR (%)
1998 Sep- 99Apr 1999:
Mar
Malaysia
Singapore
265
11
105
1
40
9
2001: Feb
Silguri (India)
66
45
68
2001: Apr-May
Meherpur, Bangladesh
13
9
69
2003:Jan
Naogaon, Bangladesh
12
8
67
2004:Jan
:Apr
Goalando, Bangladesh
Faridpur, Bangladesh
29
36
22
27
76
75
2005:Jan-Mar
Tangail, Bangladesh
12
11
92
2007:Jan-Feb
2007:Mar-Apr
2007:April
Thakurgaon, Bangladesh
Kustia, Bangladesh
Nadia, India
7
8
5
5
3
5
43
62
100
2008:February
2008: April
Manikganj and Rajbari,
Shatkira and Jessore
11
2
6
1
54.5
50
Lesson Learnt: Hendra/Nipah virus infection
•
Isolated from horses in Australia in 1994,
•
Transmission to horses may have occurred via exposure to bat.
•
Hendra & Nipah viruses similar but not identical- Henipavirus
•
Outbreaks of Nipah virus infection- were reported in
•
Malaysia (1998),
•
Singapore (1999),
•
Bangladesh (2001-08)
•
India (2001, 2007)
•
Fruit bats of genus Pteropus identified as the natural reservoir
•
Nipah is known to infect pigs, dogs, cats and horses and man
•
Contact with sick pigs was primary risk factor for infection
Chikungunya India, 2006
Chikungunya affected districts
Affected districts: 188, (in 12 States/UTs)
Suspected Cases 13.7 lakhs
Confirmed Cases 1684 out of 14505 (11.61%)
Leptospirosis
More than 1.5 billion people of Asia are at risk
•
Underreporting and misdiagnosing common
•
Epidemic potential; associated with disasters
Periodic outbreaks reported in Thailand,
India, Sri Lanka, Indonesia (rainfall and
flooding)
• Thailand: A total of 556 human cases
with 12 deaths were reported during
first five months of 2008
• Sri Lanka-reported outbreaks
•
Rodent population growth and climate change
– Major risk factors
Reported human leptospirosis cases,
5000
No. of cases
•
2001-2008, Sri Lanka
4000
3000
2000
1000
0
2001 2002 2003 2004 2005 2006 2007 2008
Year
Global distribution of leptospirosis
Swine herd’s disease
Mud Fever
Fort Brag Fever
Seven day fever
Rice Field
Leptospirosis
Cane cutter’s disease
Has been found where ever it has been looked for
Scrub typhus
 Chiggers are found throughout
Asia and Australia where rodents
are present
 Estimated 48,000 soldiers infected
in WW2
 In Thailand (Year 2000), at least
2,600 cases were reported with 5
fatal cases
 Mortality in untreated patients: 030%
 Difficult to recognize and diagnose
– underreporting!
Major Emerging Zoonoses and Challenges
Bioterrorism
•
Intentional or deliberate release of viruses, bacteria, or other germs
(agents) used to cause illness or death in people, animals, or plants
Category A agents
Anthrax, small pox, botulinum
toxin, Ebola, Marburg, plague,
tularemia
Category B agents
Epsilon toxin of Clostridium
perfringens, glanders,
melioidosis, Q fever,
psittacosis, viral encephalitis
Category C agents
Nipah, Hantavirus,
Multiple drug resistance TB
Antimicrobial resistance
• Not a new pathogen but emerging as a
public health problem
• AMR increasing at alarming rate
• Examples
• TB, E coli, N gonorrhoea, Pneumococcus,
Shigella, S aureus, Salmonella, etc..
• Causes
• Indiscriminate use of antibiotics
• Use of antimicrobial substances in food and
animal productions
Example: Penicillin resistance in
S. aureus
a continuing story...
1928
Penicillin discovered
1942 Penicillin introduced
1945
Fleming warns of resistance
1946 14% hospital strains resistant
1950
59% hospital strains resistant
1960-70s Resistance spreads in communities
1980-90s Resistance exceeds 80% (community strains)
95% ( hospital strains )
Control Strategy for Emerging Zoonoses
• Reducing human exposure- strategies to reduce human-animal
contact (coordination-veterinary and public health)
• Strengthening surveillance and early warning system
• Laboratory capacity for confirmation
• Intensifying rapid response system
• IEC/BCC- community participation in vector control
• Coordinating scientific research and development
Guiding Principles
Major Challenges
• Building core capacities for surveillance and response
at all levels – national, intermediary, local (technical
challenge)
• Mobilization of resources to meet core capacities
requirements (financial challenge)
• National Commitment to rapid sharing of information,
materials and inter-country collaboration (political
challenge)
• Disease control strategies - not one size fits all
Key tasks in dealing with emerging
diseases
• Surveillance at national, regional, global level
•
•
•
•
epidemiological,
laboratory
ecological
anthropological
• Investigation and early control measures
• Implement prevention measures
• behavioural, political, environmental
• Monitoring, evaluation
Key tasks - carried out by whom?
Global
Regional
Synergy
National
What skills are needed?
Infectious
diseases
Epidemiology
Public
Health
Telecom. &
Informatics
International
field
experience
Laboratory
Information
management
Multiple expertise needed !
WHO’s vision for the 21st Century
“A world on the alert and able to contain
communicable diseases through …”
• Strong national disease surveillance and control
programmes
• Global networks of centres, organisations and
individuals to monitor diseases
• Rapid information exchange through electronic links
to guide policies, international collaboration, trade
and travel
• Effective national and international preparedness,
and rapid response to contain epidemics of
international importance
Global CD Disease Surveillance
Global
Laboratory
Surveillance
Global
Epidemiological
Surveillance
Disease specific
global networks
(ARM, Influenza, CJD,
Rabies, VHF)
Regional Surveillance
Plan
National Surveillance
Plan
Epidemic Intelligence
(outbreak verification
team, GPHIN)
Surveillance
Standards
(Surveillance Kit)
International Health
Regulations (IHR)
Laboratory Strength.
Other networks
(other CCs, military,
Pasteur Institutes etc.)
International preparedness & response to
epidemics
(RER teams, ICG, Cholera Task Force)
National
Surveillance
Systems
Field Epidemiology
(TEPHINET, INCLEN)
Preparedness &
response to
epidemics
Global CD Disease Surveillance
Global
Laboratory
Surveillance
Global
Epidemiological
Surveillance
Disease specific
global networks
(ARM, Influenza, CJD,
Rabies, VHF)
Regional Surveillance
Plan
National Surveillance
Plan
Epidemic Intelligence
(outbreak verification
team, GPHIN)
Surveillance
Standards
(Surveillance Kit)
International Health
Regulations (IHR)
Laboratory Strength.
Other networks
(other CCs, military,
Pasteur Institutes etc.)
International preparedness & response to
epidemics
(RER teams, ICG, Cholera Task Force)
National
Surveillance
Systems
Field Epidemiology
(TEPHINET, INCLEN)
Preparedness &
response to
epidemics
WHO’s approach to surveillance
• Surveillance standards
• “Integrated” national surveillance systems
• Outbreak surveillance, verification and
response
• Field epidemiology training
• Laboratory strengthening
WHO recommended surveillance
standards
• 40 specific diseases, 8 syndromes and public
health surveillance issues addressed in the
same format
• Available in English, French,
Spanish, Arabic
• Effectively used for
National Surveillance Systems
“Integrated” national surveillance
systems
• All surveillance activities represent the “national”
surveillance system (“multi-disease approach”)
• A common resource for public health decisionmaking
• Co-ordination / synergy between
• core surveillance functions (e.g. data
collection, data reporting, data analysis)
• support surveillance functions (e.g.
epidemiology training, laboratory
strengthening)
Epidemic intelligence:
Outbreak Verification
To improve international preparedness for
epidemic response through:
• active collection of information on
ongoing outbreaks, or rumour of
outbreaks worldwide
• rapidly verify this information
• sharing relevant information with
international public health community
Summary
• Emerging and re-emerging diseases are
not new
• Their control does not require new
approaches but determination and
vigilance at all levels
• Key to success
• Sound public health practices
• Awareness and commitment of decision
makers
• Synergy
Any questions?