Transcript Emerging and Re-emerging Infectious Diseases

Emerging and Re-emerging
Infectious Diseases
Ashry Gad Mohamed, DrPH
Prof. of Epidemiology
College of Medicine, KSU.
• Emerging infectious diseases: Infectious
diseases that have newly appeared in a
population.
• Global :
• Regional:
• Re-emerging Diseases: Diseases’
incidence in human has increased during
the last 20 years or threatens to increase
in the near future.
• Global:
• Regional:
Emerging Infections in the
World since 1973
1973
1976
1977
1977
1977
1977
1980
1981
1982
1982
1982
Rotavirus
Cryptosporidium
Ebola virus
Legionella
Hantaan virus
Campylobacter
HTLV-1
Toxin prod. S.aureus
E.coli 0157:H7
HTLV-II
Borrelia burgdorferi
Enteritis/Diarrhea
Enteritis/Diarrhea
VHF
Legionnaire’s dz
VHF w/ renal flr
Enteritis/Diarrhea
Lymphoma
Toxic Shock Synd.
HUS
Leukemia
Lyme disease
1983
1983
1988
1989
1990
1991
1992
1992
HIV
Helicobacter pylori
Hepatitis E
Hepatitis C
Guanarito virus
Encephalitozoon
Vibrio cholerae O139
Bartonella henselae
AIDS
Peptic ulcer dz
Hepatitis
Hepatitis
VHF
Disseminated dz
Cholera
Cat scratch dz
1993
1994
1994
1995
1995
1996
1997
1999
1999
2001
2003
2003
2004
2005
Sin Nombre virus
Hanta Pulm. Synd.
Sabia virus
VHF
Hendra virus
Respiratory dz
Hepatitis G
Hepatitis
H Herpesvirus-8
Kaposi sarcoma
vCJD prion
Variant CJD
Avian influenza (H5N1) Influenza
Nipah virus
Encephalitis
West Nile virus
Encephalitis
BT Bacillus anthracis
Anthrax
Monkeypox
Pox
SARS-CoV
SARS
H5N1
Avian Influenza
GLOBAL EXAMPLES OF EMERGING AND
RE-EMERGING INFECTIOUS DISEASES
AS Fauci
Economic Impact of Selected
Infectious Diseases
$50bn
SARS
China, Hong Kong,
Singapore, Canada
$30-50bn
Estimated Cost
$40bn
$30bn
Foot & Mouth
UK
$25–30bn
$20bn
BSE UK,
$10-13bn
$10bn
Foot & Mouth
Taiwan, $5-8bn
Classical
Swine Fever,
Netherlands
$2.3bn
BSE
Japan
$1.5bn
HPAI, Italy
$400m
Nipah, Malaysia
$350-400m
1994
1995
1996
1997
Figures are estimates and are presented as relative size.
1998
1999
Avian Flu Asia,
$5–10bn
2000
BSE Canada
$1.5bn
Avian Flu, NL
$500m
2001
2002
BSE U.S.,
$3.5bn
2003
2004 2005
2006
Factors responsible for emerging of
infections.
I-Ecological changes and Agricultural
development.
Placing the people in contact with a
natural reserviour or host of a hitherto
unfamiliar, but usually already present,
Example 1 :
Reforestation in USA
Increased the number of deer & deer ticks
Increased
Human
contact with
deers
Deer ticks are
natural reserviour
of Lyme diseases
Human affection by Lyme disease
Example 2 :
Conversion of grassland to
maise cultivation
Rodents come to people
People
go to rodents
Rodents are
natural reserviour
of the virus
Argentine Haemorrhagic fever in
humans
• Example 3:
Pig Farm
C
h
i
n
a
Duck farm
Mixing vessels
Influenza Influenza Influenza Influenza Influenza
Increased Rice cultivation in
South East Asia.
Example 4:
Increased human contact with Field mouse
Field mouse is
natural reservoiur
of Hantaan virus
Introduction of Korean haemorrhagic fever
in Humans
Dams:
• High dam in Egypt
Slowed water flaw
allowed snails to go south
introduced S. mansoni in Upper Egypt
Increased its occurrence in Nile Delta.
• Senegal Dam
Lakes in Mauritania
Rift Valley Fever outbreak 1987.
Climate and Weather
Global warming-climatologists project temps
to increase up to 5.8°C by 2100.
Elevated rainfall
-creates new breeding habitats for
mosquitoes.
-decreases salinity which can increase
toxic bacteria.
-increases vegetation which increases
rodents.
-increases runoff into drinking reservoirs
• Higher ocean temps increase Vibrio
parahaemolyticus (shellfish)
• Some soil pathogens carried by dry
dusty winds (Coccidiodes)
II- Changes in Human
demographics and behaviours
Inflation of population size
Insufficient infrastructures
Use open containers for water
Breading mosquitos
Dengue fever in Asia
•Urbanization-more people concentrated in
cities-often without adequate infrastructure
•Increases in the elderly populations
•Increases in children in daycare: working
woman with kids under 5 was 30% in 1970,
is 75% in 2000.
•Fast paced Lifestyles- increase in
convenience items and more stress
•High-risk behavior- Drug use and
unprotected sex
War and Famine
War refugees are a full 1% of the global population
War refuges are forced onto new areas where they
are exposed to new microbes from vectors and
people.
War and famine are closely linked.
In 2001, tracking 16 countries with “food
emergencies”, showed that 9 were because of civil
unrest.
Famine is also caused by social, economic, and
political forces. Weather and HIV/AIDS
• III-International travel and Commerce.
• 365 days to circumnavigate the globe…now
it takes 36 hours
• -used to quarantine ships, but 36 h faster
than disease incubation
• 400 million people per year travel
internationally
• increased incidence of both Tuberculosis
and Influenza transmission on long flights
• -Transportation of products is an increased
concern.
• -rapid transport of disease harboring fresh
products.
• -transport of livestock facilitates movements
of viruses and arthropods (especially
ticks)
Travel and HIV/AIDS.
-Silk route and plague.
-Slaves trade and yellow fever.
-Migration to new world and smallpox.
Cholera and Hajj.
IV- Technology and industry
• Modern mass production increased the
chance of accidental contamination and
amplifies the effect of such contamination.
-Contamination of hamburger meat by
E.coli strains causing haemolytic uraemic
syndrome.
-Feeding cattle by byproducts of sheep
causing bovine spongiform encephalitis.
• Concentrating effect of blood and nasocomial
infections e.g. Ebola fever by contaminated
hypodermic apparatus.
• New diagnostic technology lead to identification
of previously unknown microbes for known
diseases e.g. Helicobacter pylori and peptic
ulcer, human herpes virus 6 and roseola.
• Medical technology
People living longer, but have weaker immune
systems.
Blood & organ transplantation transmit
infections.
V-Microbial Adaptation and Change
A number of microbes utilizing different genetic
mechanisms
-genome sequences show that lateral transfer
is common
-high mutation rates in RNA viruses-rapid
adaptation
-quick reproduction so rare mutations build up
rapidly
Antimicrobials for livestock growth enhancement
and over -prescription of antimicrobials by Drs.
(convenience)
-evolve modifying enzymes and “drug pumps”
• Increased antibiotic resistance with increased
use of antibiotics in humans and food animals
(VRE, VRSA, penicillin- and macrolide-resistant
Strep pneumonia, multidrug-resistant
Salmonella,….)
• Increase virulence (Group A Strep?)
• Jumping species from animals to humans
(avian influenza, HIV?, SARS?)
Parasites, too: Time to Development
of Resistance to Antimalarial Drugs
Chloroquine
16 years
Fansidar
6 years
Mefloquine
4 years
Atovaquone
6 months
1940
1950
1960
1970
1980
1990
Emerging Vancomycin-resistant
Enterococcal Infections in NNIS
Hospitals
25
20
% 15
ICU
Non-ICU
resistant
10
5
0
1989 1990 1991 1992 1993 1994 1995 1996 1997 1998
Is malaria an “emerging” disease?
[At least drug-resistant malaria is an emerging disaster]
YES !!!
VI- Breakdown of public health measures.
• -Decrease in choline in water supplies
lead to rapid spread of cholera in South
America.
• Non functioning water plant in Wisconsin,
USA lead to outbreak of waterborne
cryptosporidium.
• Inadequate vaccinations and Diphtheria in
former USSR independent countries.
• Discontinued mosquito control efforts and
dengue and malaria re-emergence.
Major Factors Contributing to the
Emergence of Infectious Diseases
1.
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4.
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6.
Human demographics and behavior
Technology and industry
Economic development and land use
International travel and commerce
Microbial adaptation and change
Breakdown of public health measures
Institute of Medicine Report 1992
Progress in the Eradication of
Dracunculiasis (Guinea Worm)
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1981 -- > 4,000,000 cases
1986 -- 3,500,000 cases
1989 -890,000 cases
1992 -374,000 cases
1995 -129,000 cases
1998 -79,000 cases (61%, Sudan)
1999 –
80,000 cases (70%, Sudan)
2000 -70,000 cases (73%, Sudan)
2001 -60,000 cases (78%, Sudan)
2002 -50,000 cases (74%, Sudan)
2003 -31,000 cases (62%, Sudan; 27%, Ghana)
2004 -16,026 cases (45%, Sudan; 45%, Ghana)
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2005 --
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[Down from 20 to 10 countries; 5 of them had fewer than 100 cases in 2005]
10,715 cases vs. 14,418 in 2004 (Jan-Oct)(61%, Sudan; 29%, Ghana)