Think of what you need to survive, really just survive. Food? Water? Air? Naturally, I'm going to concentrate on water here. Water is of major importance to all living things; in some organisms, up to 90% of their body weight comes from water. Up to 60% of the human body is water, the brain is composed of 70% water, and the lungs are nearly 90% water. Lean muscle tissue contains about 75% water by weight, as is the brain; body fat contains 10% water and bone has 22% water.

About 83% of our blood is water, which helps digest our food, transport waste, and control body temperature. Each day humans must replace 2.4 litres of water, some through drinking and the rest taken by the body from the foods eaten.

Waterborne diseases are caused by pathogenic microorganisms which are directly transmitted when contaminated fresh water is consumed. Contaminated fresh water, used in the preparation of food, can be the source of food borne disease through consumption of the same microorganisms. According to the World Health Organization, diarrheal diseases are responsible for the deaths of 1.8 million people every year.

It was estimated that 88% of that burden is attributable to unsafe water supply, sanitation and hygiene, and is mostly concentrated in children in developing countries. Waterborne disease can be caused by protozoa, viruses, or bacteria, many of which are intestinal parasites.

Protozoal Infections

Disease and Transmission
Amoebiasis (hand-to-mouth)

Microbial Agent
Entamoeba histolytica

Sources of Agent in Water Supply
Sewage, non-treated drinking water, flies in water supply

General Symptoms
Abdominal discomfort, fatigue, weight loss, diarrhea, bloating, fever

Disease and Transmission
Giardiasis (oral-fecal) (hand-to-mouth)

Microbial Agent
Protozoan (Giardia lamblia) Most common intestinal parasite

Sources of Agent in Water Supply
Untreated water, poor disinfection, pipe breaks, leaks, groundwater contamination, campgrounds where humans and wildlife use same source of water. Beavers and
muskrats create ponds that act as reservoirs for Giardia

General Symptoms
Diarrhea, abdominal discomfort, bloating, and flatulence

Parasitic Infections

Disease and Transmission
Schistosomiasis

Microbial Agent
Schistosoma

Sources of Agent in Water Supply
Fresh water contaminated with certain types of snails that carry schistosomes

General Symptoms
Rash or itchy skin. Fever, chills, cough, and muscle aches

Disease and Transmission
Dracunculiasis (Guinea Worm Disease)

Microbial Agent
Dracunculus medinensis

Sources of Agent in Water Supply
Stagnant water containing larvae

General Symptoms
Allergic reaction, urticaria rash, nausea, vomiting, diarrhea, asthmatic attack.

Disease and Transmission
Taeniasis

Microbial Agent
Tapeworms of the genus Taenia

Sources of Agent in Water Supply
Drinking water contaminated with eggs

General Symptoms
Intestinal disturbances, neurologic manifestations, loss of weight, cysticercosis

Bacterial Infections

Disease and Transmission
Cholera

Microbial Agent
Spread by the bacterium Vibrio cholerae

Sources of Agent in Water Supply
Drinking water contaminated with the bacterium

General Symptoms
In severe forms it is known to be one of the most rapidly fatal illnesses known. Symptoms include very watery diarrhoea, nausea, cramps, nosebleed, rapid pulse, vomiting, and hypovolemic shock (in severe cases), at which point death can occur in 12–18 hours.

Disease and Transmission
Dysentery

Microbial Agent
Caused by a number of species in the genera Shigella and Salmonella with the most common being Shigella dysenteriae

Sources of Agent in Water Supply
Water contaminated with the bacterium

General Symptoms
Frequent passage of faeces with blood and/or mucus and in some cases vomiting of blood can occur.

Disease and Transmission
Typhoid fever

Microbial Agent
Salmonella typhi

Sources of Agent in Water Supply
Ingestion of water contaminated with faeces of an infected person

General Symptoms
Characterized by sustained fever up to 40°C (104°F), profuse sweating, diarrhoea, less commonly a rash may occur. Symptoms

Disease and Transmission
E. coli Infection

Microbial Agent
Certain strains of Escherichia coli (commonly E. coli)

Sources of Agent in Water Supply
Water contaminated with the bacteria

General Symptoms
 Diarrhoea. Can cause death in immunocompromised individuals, the very young, and the elderly due to dehydration from prolonged illness.

Disease and Transmission
Salmonellosis

Microbial Agent
Caused by many bacteria of genus Salmonella

Sources of Agent in Water Supply
Drinking water contaminated with the bacteria. More common as a food borne illness.

General Symptoms
Symptoms include diarrhoea, fever, vomiting, and abdominal cramps progress to delirium and the spleen and liver enlarge if untreated. In this case it can last up to four weeks and cause death.
Viral Infections

Disease and Transmission
Poliomyelitis (Polio)

Microbial Agent
Poliovirus

Sources of Agent in Water Supply
Enters water through the faeces of infected individuals

General Symptoms
90-95% of patients show no symptoms, 4-8% have minor symptoms (comparatively) with delirium, headache, fever, and occasional seizures, and spastic paralysis resulting in paralysis or death, 1% have symptoms of non-paralytic aseptic meningitis. The rest have serious symptoms

Disease and Transmission
Hepatitis A

Microbial Agent
Hepatitis A virus (HAV)

Sources of Agent in Water Supply
Can manifest itself in water (and food)

General Symptoms
Symptoms are only acute (no chronic stage to the virus) and include Fatigue, fever, abdominal pain, nausea, diarrhoea, weight loss, itching, jaundice and depression.

Disease and Transmission
Gastroenteritis

Microbial Agent
Astrovirus, Calicivirus, Enteric Adenovirus, and Parvovirus

Sources of Agent in Water Supply
Manifests itself in improperly treated water

General Symptoms
Symptoms include diarrhoea, nausea, vomiting, fever, malaise, and abdominal pain.

Although water is best, it may vary depending on its source. Variations in water itself may have different impacts. One study reported that drinking hard tap water increased urinary calcium concentration by 50% compared to soft bottled water. On the other hand, mineral water containing both calcium and magnesium may reduce several risk factors for both calcium and uric acid stone formation.

The sad news is more than one billion people worldwide living without access to safe drinking water but the good news is the science and technology are on the way to preventing waterborne diseases worldwide.

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