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Infectious Diseases
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Infectious
Diseases
Many infectious diseases have re-emerged with a vengeance. The
loss of effective control over diseases, such as malaria and
tuberculosis, have led to a return of these diseases decades
after being kept under stringent control.
Other diseases, .which were not known to science earlier, seem
to have suddenly hit our health and our lives during the last
few decades. Two examples are Acute Immuno-Depressive Syndrome
(AIDS), due to the Human Immunodeficiency Virus (HIV) caused
through sexual transmission and Severe Acute Respiratory Syndrome
(SARS). While these cannot be directly related to environmental
change, they affect the environment in which we live by forcing
a change in lifestyles and behaviour patterns. For example,
the SARS outbreak prevented people from several countries from
traveling to other countries for months, severely affecting
national economies, airline companies and the tourism industry.
Why have infectious diseases that were related to our environment
that were under control suddenly made a comeback? Diseases like
tuberculosis have been effectively treated with anti-tubercular
drugs for decades. These antibiotics are used to kill off the
bacteria that cause the disease. However, nature's evolutionary
processes permitted the bacteria to mutate by creating new genetically-modified
strains. These mutated s,trains, which are not affected by the
routinely-used antibiotics, begin to spread rapidly.
This leads to a re-emergence of the disease. In the case of
tuberculosis, this has led to multi-drug resistant tuberculosis.
This is frequently related to HIV, which reduces an individual's
immunity to bacteria, such as mycobacterium tuberculosis that
causes tuberculosis.
The newer broad-spectrum antibiotics, antiseptics, disinfectants,
and vaccines once thought of as the complete answer to infectious
diseases have thus failed to eradicate infectious diseases.
In fact, experts now feel that these diseases will be the greatest
killers in the future and not diseases such as cancer or heart
disease.
While antibiotic resistance is a well-known phenomenon there
are other reasons for the re-emergence of diseases. Overcrowding
due to the formation of slums in the urban setting leads to
several health hazards, including easier spread of respiratory
diseases. Inadequate drinking water quality, poor disposal of
human waste due to the absence of a closed sewage system, and
poor garbage management are all urban health issues. This has
led to the reappearance of diseases such as cholera and an increased
incidence of diarrhea and dysentery as well as infectious hepatitis
(jaundice).
With increasing global warming disease patterns will continue
to change. Tropical diseases spread by vectors like mosquitoes
will undoubtedly spread malaria further away from the Equator.
Global warming will also change the distribution of dengue,
yellow fever, encephalitis, etc. Warmer wetter climates could
cause serious epidemics of diseases such as cholera. The El
Nino, which causes periodic warming, is likely to affect rodent
populations; this could bring back diseases like the plague.
Globalization and infectious
disease
Globalization is a world-wide process which includes the internationalization
of communication, trade and economic organization. It involves
parallel changes such as rapid social, economic and political
adjustments. Whilst globalization has the potential to enhance
the lives and living standards of certain population groups,
for the poor and marginalized populations in both the non-formal
as well as formal economic sectors of developing countries,
globalization enhances economic inequalities.
Tuberculosis (TB) kills approximately 2 million people each
year. In India the disease has re-emerged and is now more difficult
to treat. In 1993, the WHO declared that TB had become a global
emergency. It is estimated that between 2002 and 2020, approximately
1000 million people will be newly infected, over 150 million
people will get sick, and 36 million will die of TB if its control
is not rapidly strengthened.
TB is a contagious disease that is spread through the air. Only
people who are sick with pulmonary TB are infectious. When infectious
people cough, sneeze, talk or spit, they emit the tubercle bacilli
into the air. When a healthy person inhales these, s/he gets
infected by the disease. The symptoms include prolonged fever,
coughing spells and weight loss.
It is estimated that, left untreated, each patient of active
tuberculosis will infect, on an average, between 10-15 people
every year. But people infected with TB will not necessarily
get sick with the disease. The immune system can cause the TB
bacilli, which is protected by a thick waxy coat, to remain
dormant for years. When an individual's immune system is weakened,
the chances of getting active TB are greater.
- Nearly 1 % of the world's population is newly infected
with TB each year.
- It is estimated that overall, one-third of the world's
population is likely to be infected with the tuberculosis
bacillus at some point in time.
- 5-10% of the people who are infected with TB (but who
are not infected with HIV) become sick or infectious at
some time during their life (WHO, 2002).
- TB kills about 2 million people each year (including persons
infected with HIV).
- More than 8 million people become sick with TB each year,
one person in the world every second!
- About 2 million TB cases per year occur in sub-Saharan
Africa. This number is rising rapidly as a result of the
HIV / AIDS epidemic.
- Around 3 million TB cases per year occur in South-east
Asia.
- Over a quarter of a million TB cases per year occur in
Eastern Europe.
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