Water-based diseases
Those caused by aquatic organisms that spend part of their life cycle in the water and another part as parasites of animals.
Water-based diseases include Guinea worm disease, filariasis (also a vector disease), paragonimiasis, clonorchiasis and schistosomiasis. These diseases are caused by a variety of flukes, tapeworms, roundworms and tissue nematodes, often referred to as helminths, that infect humans. Although these diseases are not usually fatal they prevent people from living normal lives and impair their ability to work.
The prevalence of water-based diseases often increases when dams are constructed, because stagnant water behind dams is ideal for snails, the intermediary host for many types of worms. For instance, the Akosombo Dam, on Volta Lake in Ghana and the Aswan High Dam on the Nile in Egypt have resulted in huge increases of schistosomiasis in these areas.
Schistosomiasis (bilharzia)
Of the 200 million people in the world infected with the worm that causes schistosomiasis, some 20 million suffer severe consequences, such as renal failure, bladder cancer, and liver fibrosis. The disease is still found in 74 countries.
Studies show that the disease has been cut by 77% in some areas through providing better drinking water and sanitation access.
88 million children under fifteen years of age are infected each year with schistosomes.
80% of transmission takes place in Africa south of the Sahara.