Eurfent comments”

Schistosomiasis is a waterborne, parasitic disease, found in much of the Third World. The World Health Organization (WHO) ranks schistosomiasis as one of the predominant tropical diseases in terms of socioeconomic and public health importance. I It is endemic in 74 countries and threatens as many as 600 million people as they perform daily activities related to water such as swimming, fishing, farming, washing, and bathing. In extreme cases, schistosomes, the parasites causing schktosomiasis, can survive for decades in their human host. Whale schistosomiasis is predominantly a disease of the rural poor, travelers to endemic areas are also subject to infection. Schistosomes belong to the phylum Platyhelminthes, the flatworms, and are commonly known as blood flukes. Figure 1 shows the complex life cycle of the schistosome, which involves an aquatic snail intermediate host, the human or animal definitive host, and the mutual presence of both snail and definitive host in the environment in which transmission occurs. Adult flukes live in human blood vessels, particularly those supplying the intestines, liver, and bladder. Kenneth S. Warren, director for health sciences, Rockefeller Foundation, New York, notes that while these flukes produce large numbers of eggs in the vessels of these organs, they do not multiply in the human body.z Some of the eggs pass out of the body via the urine or feces and hatch if they reach fresh water. FreeMarch 3, 1986