EMERGING AND REEMERGING
INFECTIOUS
DISEASES
IMPORTANT TERMS
•
Emerging infectious disease- An infectious disease that has newly appeared in a population
or that has been known for some time but is rapidly increasing in incidence or geographic
range.
•
Re-emerging infectious disease- diseases that once were major health problems globally or
in a particular country, and then declined dramatically, but are again becoming public health
problems for a significant proportion of the population.
•
Infectious diseases- are caused by pathogenic microorganisms, such as bacteria, viruses,
parasites or fungi; the diseases can be spread, directly or indirectly, from one person to
another.
•
Zoonotic diseases- are infectious diseases of animals that can cause disease when
transmitted to humans.
INTRODUCTION
• In developing countries where much of the population lives in conditions of
extreme poverty, infectious diseases remain the leading cause of death
• In the U.S., prevention and control of infectious diseases have been so
successful in the past half century that many people view infectious diseases
as either a thing of the past or minor illnesses easily treated and cured
http://www.cdc.gov/nchs/data/databriefs/db115_fig4.png
CAUSES OF DEATH IN HIGH- INCOME COUNTRIES (2012)
http://www.who.int/mediacentre/factsheets/fs310/en/index1.html
CAUSES OF DEATH IN LOW- INCOME COUNTRIES (2012)
http://www.who.int/mediacentre/factsheets/fs310/en/index1.html
EXAMPLES OF EMERGING INFECTIOUS
DISEASES
•
Ebola virus (first outbreaks in 1976 and the discovery of the virus in 1977)
•
HIV/AIDS (virus first isolated in 1983)
•
Hepatitis C (first identified in 1989, now known to be the most common cause of posttransfusion hepatitis worldwide)
•
Influenza A(H5N1) virus (well known pathogen in birds but first isolated from humans in
1997)
EXAMPLES OF EMERGING INFECTIOUS
DISEASES
•
Legionella pneumophila (first outbreak in 1976 as Legionnaire disease and since
associated with similar outbreaks linked to poorly maintained air conditioning systems )
•
E. coli O157:H7 (first detected in 1982, often transmitted through contaminated food, has
caused outbreaks of hemolytic uremic syndrome)
•
Borrelia burgdorferi (first detected in 1982 and identified as the cause of Lyme disease)
•
Severe Acute Respiratory Syndrome (SARS) (first detected in 2003 in Asia); the first
emerging infectious disease of the 21 st century
•
Swine Flu Influenza A (H1N1) (first observed in 2009 in Mexico)
EBOLA
•
Has a fatality rate of 50-90%
•
Experts continue the fight to control the Ebola haemorrhagic outbreak in western
Uganda. The outbreak, now in its second week, has claimed at least 16 lives out
of 53 cases reported. Ebola is caused by one of the most virulent pathogens
known to humankind (WHO, 2012).
•
No specific treatment or vaccine is yet available for EHF. New drug therapies
have shown promising results in laboratory studies and are currently being
evaluated. Several vaccines are being tested but it could be several years before
any are available.
E. COLI 0157:H7
• E. coli 0157:H7- More deadly strain
appeared in 1982
• passed from person to person (in
feces)
• contaminated food, contaminated
water or other liquid
• Raw milk
• In 1993 Washington State
• Jack –in-the-Box hamburgers
• Outbreak killed 4 children and
700 persons became ill
As of March 21, 2012, 58 persons infected with
the outbreak strain of E. coli O157:H7 (associated
with Romaine Lettuce) were reported from 9
states. The number of ill persons identified in each
state was as follows: Arizona (1), Arkansas (2),
Illinois (9), Indiana (2), Kansas (2), Kentucky (1),
Minnesota (2), Missouri (38), and Nebraska (1).
This particular outbreak appears to be over and
consumers are not being advised to avoid eating
any specific foods at this time.
FACTORS INVOLVED IN THE EMERGENCE OF
INFECTIOUS DISEASES
1.
Unprecedented worldwide population growth, urbanization
2.
Increased international travel
3.
Increased worldwide transport, migration, and relocation of
animals and food products
4.
Changes in food processing, handling, and agricultural practices
5.
Changes in human behaviour, technology and industry
6.
Human encroachment on wilderness habitats that are reservoirs
for insects and animals that harbour infectious agents
FACTORS INVOLVED IN THE EMERGENCE OF
INFECTIOUS DISEASES
7.
Microbial evolution and the development of resistance to antibiotics and other
antimicrobial drugs
8.
Changes in ecology and climate
9.
Modern medicine (e.g. immunosuppression), human susceptible to infection
10.
Inadequacy of public infrastructure and vaccination programs
11.
Social unrest and civil wars
12.
Bioterrorism
13.
Virulence-enhancing mechanism of pathogens (the mobile bacteriophages, plasmids,
transposons)
INFECTIOUS DISEASES ON THE RISE
• Many diseases thought to be adequately controlled appear to be
making a “comeback”
• In developed countries, public health measures such as sanitation,
sewage treatment, vaccination programs, and access to good
medical care have virtually eliminated “traditional” diseases such
as:
• Diptheria, whooping cough, and tuberculosis
• Many of these diseases are becoming a public health problem
once again, as immunization programs and other public standards
are enforced less vigorously and, as antibiotic resistant pathogens
evolve
INFECTIOUS DISEASES ON THE RISE
• Strains of pneumonia-caused by Staphylococcus aureus are
resistant to all of the currently available drug treatments
• Among the diseases “reemerging” as a consequence of
microbial resistance are:
• Tuberculosis, and malaria, leading causes of death from
infectious diseases worldwide
INFECTIOUS DISEASES ON THE RISE
• Global spread of AIDS
• Resurgence of tuberculosis
• Appearance of new enemies (hantavirus, hepatitis C and E, Ebola virus,
Lyme disease, cryptosporidiosis and E. coli O157:H7
• Bird flu which attacks the Southeast Asia
• Prion disease of Creutzfeldt-Jakob disease
• Antibiotic resistance Staphylococcus bacteria
• Several major multistate foodborne outbreaks
• Whooping cough (pertussis)
• A new strain of drug resistance tuberculosis
WHOOPING COUGH (PERTUSSIS)
•
Whooping cough—or pertussis—is a very serious respiratory (in the lungs and breathing
tubes) infection caused by bacteria. It causes violent coughing you can’t stop. Whooping
cough is most harmful for young babies and can be deadly.
•
Among vaccine-preventable diseases, (the DTaP vaccine protects against whooping
cough), pertussis is one of the most commonly occurring ones in the United States.
•
In Washington, there have been 3,285 cases reported statewide through July 28,
2012, compared to 253 reported cases in 2011 during the same time period. There
were 965 cases reported statewide in 2011 compared to 608 reported cases in 2010.
Visit the Washington State Department of Health for the most recent information.
•
In 2011 and the start of 2012, an increase in pertussis cases has been reported in
Argentina1, Colombia2, Chile3, Canada and the USA,4 with cases predominantly in
adolescents and newborns.
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
POSSIBLE SOLUTIONS
Public health surveillance & response systems
• Rapidly detect unusual, unexpected, unexplained disease
patterns
• Track & exchange information in real time
• Response effort that can quickly become global
• Contain transmission swiftly & decisively
• Questions??