Water diseases
Diarrhoea is not a disease but a symptom of many diseases. Diarrhoeal diseases are the most deadly of the water and sanitation diseases, of which cholera, bacillary dysentery and typhoid are the worst. There are over four billion cases of diarrhoea every year, spread through poor water, contaminated food, the insanitary disposal of human waste and poor hygiene. Diarrhoea causes the rapid depletion of water and sodium in the sufferer. If these are not replaced quickly, the body starts to become dehydrated and the body's salt balance is severely damaged. If more than 10% of the body's fluid is lost the sufferer dies.
Diarrhoeal diseases can be prevented by improving access to clean water and sanitation so that bacteria cannot re-enter water supplies and through hygiene education so that communities practice safe hygiene. The keys to prevention are clean water, clean hands at mealtimes and uncontaminated food.
Water is also a factor in many other types of disease:
Water-based diseases
These are caused by organisms that spend part of their lives in the water, and then part as parasites that infect humans. E.g. guinea worm, bilharzia. These parasites can lead to malnutrition and anaemia.
Water-related vector diseases
These are caused by mosquitoes and flies which live or breed around water e.g. malaria, yellow fever, dengue fever, sleeping sickness.
Water-scarce diseases
These are transmitted in places where water is too scarce to allow people to wash themselves, their clothes or their homes very often e.g. trachoma and scabies.