What are water-borne diseases?
Water-borne diseases are any illnesses caused by drinking contaminated water. The contamination can be occurred by bacteria such as Salmonella or Campylobacter, viruses, or small parasites including Cryptosporidia, Giardia, and on rare occasions Toxoplasma.

How are they spread?
Most outbreaks of water-borne disease are caused by the contamination of drinking water systems with the faces of infected animals or people. This is likely to occur where public and private drinking water systems get their water from surface waters, such as rain, creeks, rivers and lakes. These surface waters can be contaminated by infected

Figure 1. Spread of water-borne disease

Four Groups of Contaminants

Microbial Pathogens:  Pathogens in drinking water are serious health risks. Pathogens are disease-producing micro-organisms, which include bacteria, viruses, and parasites. They get into drinking water when the water source is contaminated by sewage and animal waste, or when wells are improperly sealed and constructed. They can cause gastroenteritis, Salmonella infection, dysentery, shigellosis, hepatitis, and giardiasis (a gastrointestinal infection causing diarrhea, abdominal cramps, and gas).

Organics:  People worry the most about potentially toxic chemicals and metals in water. Only a few of the toxic organic chemicals occur drinking water are regulated by drinking water standards. This group of contaminants includes:

• Trihalomthanes (THMs), which are formed when chlorine in treated drinking water combines with naturally occurring organic matter.
• Pesticides, including herbicides, insecticides, and fungicides.
• Volatile organic chemicals (VOCs), which include solvents, degreasers, adhesives, gasoline additives, and fuels additives. Some of the common VOCs are: benzene, trichloroethylene (TCE), styrene, toluene, and vinyl chloride. Possible chronic health effects include cancer, central nervous system disorders, liver and kidney damage, reproductive disorders, and birth defects.

Inorganics:  These contaminants include toxic metals like arsenic, barium, chromium, lead, mercury, and silver. These metals can get into your drinking water from natural sources, industrial processes, and the materials used in your plumbing system. Toxic metals are regulated in public water supplies because they can cause acute poisoning, cancer, and other health effects.

Nitrate is another inorganic contaminant. The nitrate in mineral deposits, fertilizers, sewage, and animal wastes can contaminate water. Nitrate has been associated with "blue baby syndrome" in infants.

Radioactive Elements:  Radon is a radioactive contaminant that results from the decay of uranium in soils and rocks. It is usually more of a health concern when it enters a home as a soil gas than when it occurs in water supplies. Radon in air is associated with lung cancer.

What are the symptoms of water-borne diseases?
Many people who get infected with the more common water-borne disease agents will have no symptoms at all, and probably will not even know they have been infected. Over time, their bodies will gradually eliminate the infection and their health will not be affected.
For people who do get sick from water-borne disease, the symptoms vary depending on the infectious agent. For many water-borne diseases, symptoms begin from two to ten days after drinking the contaminated water, and may include diarrhea, stomach cramps, nausea, vomiting, and low-grade fever. People with toxoplasmosis may have fever, swollen glands and loss or blurring of vision.

Who are most severely affected?
Persons who have suppressed immune systems, such as persons who have HIV/AIDS, persons who have had an organ or bone marrow transplant, or who have had cancer treatment, are at greater risk from water-borne diseases. For these people, infection may be more severe and may become life-threatening. Babies, the very elderly, and those whose health is fragile due to chronic disease may have more serious complications.
The risk of getting toxoplasmosis through drinking water is very rare. Toxoplasmosis is of particular concern during pregnancy, as a growing fetus can become infected with the toxoplasmosis parasite. This can happen if the mother is infected with the parasite while pregnant or before she becomes pregnant. This can lead to serious long-term complications for the baby if the disease is not detected and treated at an early stage.

Possible Health Effects
The levels of contaminants in drinking water are seldom high enough to cause acute (immediate) health effects. Examples of acute health effects are nausea, lung irritation, skin rash, vomiting, dizziness, and even death.
Contaminants are more likely to cause chronic health effects - effects that occur long after repeated exposure to small amounts of a chemical. Examples of chronic health effects include cancer, liver and kidney damage, disorders of the nervous system, damage to the immune system, and birth defects.
Evidence relating chronic health effects to specific drinking water contaminants is limited. In the absence of exact scientific information, scientists predict the likely adverse effects of chemicals in drinking water using human data from clinical reports and epidemiological studies, and laboratory animal studies.

What should I do if I think I have a water-borne disease?
See your doctor as soon as possible if your illness is severe or prolonged, or if you have one of the above noted conditions that put you at increased risk.
Your local public health unit should also be notified so that the source of infection can be located and controlled.

Waterborne disease kills 9 in Nicaragua
Leptospirosis spread by flooding after intense rains in region

29 October 2007

MANAGUA, Nicaragua - A waterborne disease spread through animal urine has killed nine people and sickened more than 1,600 in storm-stricken Nicaragua.
The disease, leptospirosis, was spread by flooding caused by a month of intense rains and category-5 Hurricane Felix, which hit north-eastern Nicaragua.

Nine people had died of the disease and 1,606 people had fallen ill, Lt. Col. Guillermo Lopez, deputy chief of the country's Civil Defense Department, told reporters.

References
http://www.bae.ncsu.edu/programs/extension/publicat/wqwm/he393.html
http://www.bchealthguide.org/healthfiles/pdf/hfile49a.pdf

Figure retrieved from,
http://www.eurekaforbes.com/images/press/waterdisease.jpg

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