Waterborne
Diseases
Diseases
The lack of clean water resources
and sanitation facilities looms as one of the most serious environmental health problems faced today by a large fraction of the world's population, especially
those living in developing regions.
The onset of waterborne diseases in
water is enormous and largely attributed by the fact that the World Health
Organization (WHO) has estimated that 1.1 billion people globally lack basic
access to drinking water resources, while 2.4 billion people have inadequate sanitation facilities, which clearly accounts for many water related acute and chronic diseases.
Some 3.4 million people, many of
them young children, die each year from water-borne diseases, such as
intestinal diarrhea (cholera, typhoid fever and dysentery), caused by microbially-contaminated
water supplies that are linked to deficient or non-existent sanitation and
sewage disposal facilities.
Globally,
water-borne diseases are the second leading cause of death in children below
the age of five years, while childhood mortality rates from acute respiratory
infections ranks first.
Around the world,
water supply and sanitation facilities are rapidly deteriorating and currently
are operating at a fraction of its installed capacity.
This situation is
particularly serious in many urban regions of developing countries in Asia,
Africa and Latin America where the poor have very limited access to clean water
supplies and sanitation facilities, which pose infectious disease risks to the population, especially among infants and young children.
This situation is
often more pronounced in rural areas, where the problem of water resources and
inadequate sanitation facilities still largely remains to be solved.
Added to this is
the rapid industrialization of many developing regions, where in the past few
decades water contamination by toxic chemicals and hazardous wastes has aggravated an already serious water pollution problem.
Many freshwater streams and lakes around the world have been contaminated with industrial discharges and agricultural runoffs that carry a large variety of toxic
chemical substances and hazardous wastes.
Many contaminated
water sources contain a number of heavy metals, pesticides and other agricultural chemicals, along with persistent organic pollutants (POPs).
Many of these
remain in the environment for long periods of time and bioaccumulate in the
food web, causing many acute and chronic diseases, ranging from severe skin and
liver disorders to developmental abnormalities and human cancer.
The Hemispheric
Picture : In a report based on the Meeting of Environment Ministers of the
Americas, held in Montreal, Canada on March 29 - 30, 2001, which represented 33
countries in the Western 2 Hemisphere, the environmental threats to public
health from contaminated drinking water was summarized as follows:
"Although important progress has
been made in recent years, approximately 90 million people in the Americas
still do not have ready access to water. Many of those who do have the benefit
of being connected to a water source, drink water that can make them
sick."
Threats
to water quality can be biological and chemical. About 300 million people in
the Americas are at risk of contracting serious diseases such as cholera,
typhoid fever, and viral hepatitis.
Parasites
such as Giardia and Cryptosporidium are also a serious threat, particularly in
developing countries. Biological and chemical contaminants enter source waters
mainly through the discharge of human, animal and industrial wastes.
In
Latin America and the Caribbean less than 12% of collected wastewater is
treated. This means that enormous amounts of raw sewage, along with industrial
effluents and run-off water contaminate the ground and surface water sources
needed for public water supplies.
It
is estimated that a reduction in the incidence of certain bacteriological
diseases of up to 80% could be achieved through effective water source
protection from raw sewage.
Even
where most people have access to treated water, there is an ever present risk
of outbreak of waterborne diseases or other human illnesses from direct
ingestion of, or exposure to, contaminated water or the consumption of any
foods so contaminated by water.
In
Canada, mostly in small towns and villages, many "boil water"
advisories are regularly issued over concerns about the microbiological safety
of the water.
The
threat from waterborne disease was highlighted in the spring of 2000, when the
spread of E. Coli bacteria in the drinking water supply of a small town
resulted in several deaths and a large number of ill people.
Disparity
in water supply is also an issue. Poor people are less likely to be connected
to regular sources of water supply and often are forced to purchase highly
priced poor quality water from vendors.
The
high cost of water and lack of quality are generally responsible for the low
level of personal hygiene and associated spread of communicable diseases, and
high prevalence of water related diseases.
Inequities
are also visible between water supply coverage in urban and rural populations.
A
recent global assessment carried out by WHO-PAHO-UNICEF indicates that in most
developing countries the best-served rural dweller is much worse off than the
worst-served urban dweller.
Insufficient
and ineffective management of surface and coastal waters also has important
detrimental impacts on the potential for rivers and beaches to be used for
bathing, swimming and other recreational activities.
Not
only does this cause 3 problems to public health, but it can also be responsible
for the loss of revenue from tourism."
Summary of Water-Related
Diseases Worldwide: ·
Bacterial Diseases: According to WHO and the US Centers for Disease Control and
Prevention (CDC), over 2 billion people, mostly living in developing countries,
are at elevated risk to water related bacterial diseases.
While
there are many illnesses that may be identified in this category, the major
water related diseases include acute dehydrating diarrhea (cholera), abdominal
illness (typhoid fever), acute diarrhea (dysentery) and chronic diarrhea
(Brainerd diarrhea).
The
following is a more precise description of these culprits...
· Cryptosporidiosis: In
the past two decades, in many regions of the world, including the United
States, a common water related diarrhea disease that is increasingly been
recognized as a major public health problem is cryptosporidiosis, caused by a
microscopic parasite (Cryptosporidium).
It
is generally found in drinking water, swimming pools and recreational streams
that have been accidentally contaminated by human fecal wastes.
· Giardia: Another
increasingly common water related diarrhea disease around the world, including
the United States, is giardiasis, which is caused by a one-celled microscopi
parasite (Giardia).
Similar
to the spread of cryptosporidium in the environment, giardia is transmitted by
discharges of fecal wastes into water, food, soil and other surfaces, and
therefore the preventative hygienic measures that are being recommended to
lower the overall incidence of the former disease applies here equally well.
· Malaria: One
of the most serious vector-borne diseases in the world today is malaria.
It
occurs in many tropical regions of the world, such as Central and South Africa,
Hispaniola, the sub-Saharan region of Africa (where the largest incidences are
annually reported), Indian subcontinent, Southeast Asia, Middle East and
Oceania.
It
is a water related disease, since it is caused by four subspecies of
microscopic parasites (Plasmodium) carried by female Anopheles mosquitoes that
breed its larvae in stagnant waters and storage reservoirs in warm climates.
· Malarial Incidence: Each
year, 300 to 500 million people contract malaria worldwide, of which 1.5 to 2.7
million people die from the disease, the overwhelming majority (90%) of them
children below the age of 5 years.
Since
the 1970s, there has been a resurgence of malaria in different regions of the
world, partially due to the rapid formation of resistant parasites to malaria
preventing drugs, such as chloroquine and other quinoline products.
In
addition, significant increases in the incidence of malaria in recent years
have been caused by the construction of dams, intensified irrigation systems
and other water related projects, which have become new mosquito breeding sites
in many developing regions.
· Schistosomiasis: It
is estimated that 200 million people worldwide are infected with schistosomiasis,
with another 2 billion people in some 74 countries are at elevated risk from
this debilitating water-borne disease.
Schistosomiasis
(sometimes known as bilharzias) is caused by parasitic worms (Schistosoma) when
human beings come into contact with certain types of snails that harbor these
parasites in contaminated fresh 4 water.
The
main factor in the proliferation of this disease is when human fecal wastes are
dumped in fresh water sources.
The
problems of water pollution and drinking water contamination in the two North
America countries tend to be similar in nature, since the types of industrial
and municipal discharges, disposal of hazardous wastes and agricultural runoffs
are not markedly different.
The
chemical and biological contaminants in drinking water that have serious
potential impacts on human health are numerous.
In
recent years, several water-borne infectious diseases outbreaks have occurred
in United States and Canada that were caused by parasites found in contaminated
rivers and lakes.
These
include Cryptosporidium and Giardia, which enter surface waters through improper
sewage disposal and animal wastes. ·
The
extensive chlorination in United States and Canada to destroy pathogenic
bacteria in drinking water supplies has lead to an even larger problem; the
formation of disinfectant by-products, such as halogenated hydrocarbons.
One
class of these halogen-containing organic 7 compounds - trihalomethanes (e.g.,
chloroform) - pose long-term health impacts on the general population, such as
liver, kidney, central nervous system disorders and may pose an increased risk
of contracting cancer.
The
widespread use of the fuel additive MTBE in the United States has led to its
increasing presence in many surface and ground water sources in the country.
While
the long-term toxicity of MTBE has been documented, a drinking water standard
for this pervasive contaminant has not been established as yet by the United
States Environmental Protection Agency.
Drinking
water sources may also contain radioactive substances, such as Radium 226/228
and a variety of beta-emitting minerals found in underground aquifers.
These
contaminants pose cancer risks to individuals who ingest radioactive sources of
drinking water over a long period.
In
addition, radon gas in the soil can dissolve and accumulate in ground water
posing health risk to communities that ingest such contaminated sources of
water.
Radioactive
radon has been shown in recent years to be a potential cancer causing
substance.
Worldwide,
dirty water will continue to be the cause of numerous diseases and rank second
only to poor nutrition in causing human suffering and death.
Poor
nutrition, poor hygiene and poor sanitation often go hand-in-hand with an
inadequate supply of good quality water, especially in the highly-populated
developing countries.
Studies
have estimated that there are as many as 4 billion cases of diarrhea worldwide
each year due to consumption of contaminated water and that 2.2 million people
die each year from diarrhea diseases.
And
until the quality of the water is increased, theses waterborne disease
conditions will likely remain.
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