The six diseases of WHO. Schistosomiasis: some advances.

In man schistosomiasis is caused by three main trematode species, Schistosoma mansoni, S haematobium, and S japonicum. Other species that infect man are S intercalatum, S mattheei, and S mekongi, and various mammalian and avian schistosomes that do not complete their life cycles in the human host but may cause cercarial dermatitis or "swimmer's itch." Some 200 million people are probably infected with schistosomiasis and 500-600 millions exposed to the risk of infection. The disease has a