Emerging and Re-emerging Infectious Diseases

Emerging and Re-emerging 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

http://www.who.int/mediacentre/factsheets/fs310/en/index1.html

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)

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 post-transfusion 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

Unprecedented worldwide population growth, urbanization

Increased international travel

Increased worldwide transport, migration, and relocation of animals and food products

Changes in food processing, handling, and agricultural practices

Changes in human behaviour, technology and industry

Human encroachment on wilderness habitats that are reservoirs for insects and animals that harbour infectious agents

Factors involved in the emergence of infectious diseases

Microbial evolution and the development of resistance to antibiotics and other antimicrobial

drugs

Changes in ecology and

climate

Modern medicine (e.g. immunosuppression

), human susceptible to infection

Inadequacy of public infrastructure and vaccination

programs

Social unrest and civil

wars

Bioterrorism

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 globalContain transmission swiftly & decisively

Questions??