Download Presentation on emerging infections

Emerging infections
•  Perspectives
•  Examples
•  How to predict/ prepare/ prevent/ handle
Perspective on infectious disease
•  One can think of the middle of twentieth century as the end
of the most important social revolutions in history, the
elimination of the infectious disease as a significant
factor in social life . . . .
• 
- Sir McFarland Burnet, 1962
•  It is time to close the book on infectious diseases and
pay more attention to chronic ailments such as cancer and
heart disease…..
- William H Steward, 1968
Emerging infectious diseases
Emerging infectious diseases
Emerging infectious diseases
Emerging infectious diseases
Outbreak reports WHO 2007
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Avian influenza – situation in Indonesia
Meningococcal disease in Uganda
Rift Valley Fever in Kenya
Yellow fever in Togo
Poliomyelitis in Chad
Extensively Drug-Resistant Tuberculosis (XDR-TB) in United States
of America air passenger
•  Marburg haemorrhagic fever in Uganda
•  Ebola haemorrhagic fever in the Democratic Republic of the Congo
Perspective on infectious disease
• 
Emerging infectious diseases present one of the most significant health
and security challenges facing the global community . . . . We are committed
to ensuring that American citizens have the best protection possible from
emerging infectious disease, and that means coordinated, comprehensive
approach at both the national and international levels.
- Vice President Albert Gore, 1996
• 
“. . . In the highly interconnected and readily traversed ‘global village’ of
our time, one nation’s problem soon becomes every nation’s problem . . .”
“Microbial Threats to Health: Emergence, Detection, and Response”, Institute of
Medicine, March 2003.
Health and development
Creating the circumstances for the spread of infectious diseases
Emerging virus infections in the last decennia
Mobility
Demography: rapidly Increasing Human
Population
•  1 billion people until
1800
•  6.1 Billion people in
2000
•  ~9.4 to 11.2 Billion in
2050
Source: United Nations, World Population Prospects, The
1998 Revision; and estimates by the Population Reference
Bureau.
Climate changes
Climate changes
Identifying candidate diseases for early warning systems
by WHO
•  Cholera
•  malaria
•  meningococcal meningitis
•  dengue/ dengue hemorrhagic fever
•  leptospirosis
•  yellow fever
•  japanese and St Louis encefalitis
•  rift valley fever
•  african trypanosomiasis
•  leishmaniasis
•  west nile virus
•  murray valley fever and Ross rive virus
Outbreak examples
•  SARS
•  HIV
•  Malaria
•  Avian Influenza
•  Hepatitis B
•  Hemorrhagic fevers
•  ...
SARS
SARS Outbreak
•  In November 2002, highly contagious and severe atypical
pneumonia were observed in the Guangdong Province of
southern China
• 
The virus was spread to Hong Kong in February 2003 by a
doctor who died 10 days after admission into local hospital
 a mysterious death
• 
Similar outbreaks occurred at different local communities
subsequently
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The virus was identified by Hong Kong, the U.S. Germany in
March 2003, and The Netherlands
Effect of Travel and Missed Cases on the
SARS Epidemic
Spread from Hotel M, Hong Kong
Canada
Guangdon
g Province,
China
F,G
A
F,G
A
Hong Kong
SAR
95 HCW
>100 close contacts
H,J
H,J
B
B
11 close
contacts
K
Hotel M
Hong
Kong
A
18 HCW
K
Ireland
0 HCW
I, L,M
C,D,E
C,D,E
Vietnam
Singapore
37 HCW
34 HCW
21 close
contacts
37 close
contacts
I,L,M
United
States
1 HCW
SARS
SARS
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The Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO)
are investigating a worldwide outbreak of unexplained atypical pneumonia
referred to as Severe Acute Respiratory Syndrome (SARS).
• 
As of 10 April 2003, over 2,500 suspected cases of SARS have been reported to
WHO from nearly 20 countries; in the United States, over 150 suspected cases (about 5% of cases
worldwide) have been reported to CDC from about 30 states. Of the United States cases, about 95%
had traveled to outbreak areas listed in the case definition within 10 days prior to the onset of clinical
illness, and the remainder had a history of close contact with a person with suspected SARS.
• 
Of these cases reported worldwide, approximately 3.5
% (over 100 cases) have been
fatal. In the United States, the majority of patients have recovered or stabilized clinically without
specific antiviral therapy; no fatalities have been reported as of 10 April 2003.
• 
Laboratories at CDC and elsewhere (SARS Laboratory Network organized by WHO) have
detected a new coronavirus in SARS patients. Less often, a paramyxovirus
(metapneumovirus) also has been found. Both are lipid-enveloped, singlestranded RNA viruses. The
identification of a novel coronavirus is consistent with a potential etiologic role, but the pathogenesis
of SARS remains unclear at the present early stage of research. A co- factor role of paramyxovirus in
this syndrome cannot be excluded. A diagnostic test for SARS based on the detection of acute
infection with the novel coronavirus is currently under development.
Globe Impacts of SARS
Toronto airport
Railway station full with
people leaving Beijing
“The terror of the unknown is
seldom better displayed than by
the response of a population to
the appearance of an epidemic,
particularly when the epidemic
strikes without apparent cause”
Quote from Edward Kass, 1977
Worldwide: 59 US$ billion
China, mainland: 17.9 US$ billion, 1.3% GDP
Hong Kong: 12 US$ billion, 7.6% GDP
“Normal life affected”
By Dr. Hu AnGang, Nov. 11, 2003
International conference of AIDS and
SARS, Qinghua University, Beijing
HIV
HIV
HIV
HIV
Malaria
How is “AI” spread?
Animal & human populations in close proximity
- farm animals and pets in/under/next to houses
- live animal markets (many species from many countries)
Poor agricultural practices
- inadequate infection control on farms
- poultry excrement used in agriculture (e.g. fed to pigs)
Poor food hygiene
- food preparation practices
- consumption of raw/undercooked meat
Frequent travel/trade involving humans and birds
- movement of people/animals among farms
- legal and illegal animal trade
- wild bird migration
Avian Flu
What is Avian Influenza?
Hepatitis B distribution
Hepatitis B
•  300 miljon carriers worldwide
•  Perinatal transmission/ horizontal transmission!/ sexual contact/ IV
drugsabuse
•  incubation 1-4 months
•  progression from acute to chronic 90% in perinatal infection/
20-50% between age 2-5 jaar and less than 5% in adults
•  mortality caused by cirrhosis/ HCC
(higher chance if HbeAg pos)/ decompensated livercirrhosis
•  alcohol enhances cirrhosis
Cirrhosis and livercell carcinoma
Viral hemorrhagic fevers (VHF)
Epidemiology
Geographic spread VHF
Dengue
Yellow fever
Rift valley fever
Geographic spread VHF
Ebola, Marburg
Lassa
Crimean-Congo
HF
Dengue distribution
50-100 million Dengue infections annually
2500-3000 million people at risk for
Dengue virus transmission
Lassa fever
Diagnosis
•  Lassa-fever, by RT-PCR
Lassa fever
•  West Africa
•  100.000 cases, 5000 deaths
•  Rats  shed virus via
excreta
•  Infection: direct/indirect
contact
•  Transmissible person-toperson
Human Ebola outbreaks in Africa
Pourrut et al, Microbes Infect
2005
Marburg hemorrhagic fever
Epidemiology
•  First recognized in 1967 Marburg and
Belgrade laboratory workers, infected
monkeys from Uganda
•  25 cases, 7 deaths, 6 secondary cases
•  1975: South Africa (via Zimbabwe?)
•  1980: Kenya
•  1987: Kenya
•  1998–2000: Dem. Republic of Congo
Angola outbreak 2004-2005
•  163 cases, 150 deaths
Outbreak management
How to predict/ prepare/ prevent/ handle
 local and global surveillance systems
  Public health system and mechanisms for response to emerging diseases
should be based on science
  The governments, scientific communities and industry should work
together for fighting the emerging diseases
  Economic development should be balanced with the social development
  There should be a harmonious relationship between man and nature
Conclusion