Published on August 17, 2011   37 min

A selection of talks on Clinical Practice

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I'm Alan Fenwick. I'm a professor of tropical parasitology in Imperial College, London. And I'm Director of the Schistosomiasis Control Initiative, also in London. But we work, controlling this disease, in several countries, particularly in sub-Saharan Africa.
So schistosomiasis, which is also commonly known as bilharzia, is caused by trematode worms which inhabit the blood vessels around the bladder or in the mesentery of the human hosts.
Worldwide, there are several species which infect humans. But there are three major species. In sub-Saharan Africa, there are two major species. One is Schistosoma haematobium, which causes urinary schistosomiasis. It's only found in Africa, and there is no animal reservoir. The second species in Africa is Schistosoma mansoni, which is also known as intestinal schistosomiasis. Not only is it found in Africa, however, but it was also exported to South America, probably with the slaves. And it's quite possible that some rodents and primates can be infected with Schistosoma mansoni. The third major species is Schistosoma japonicum, which also causes intestinal schistosomiasis. And several years ago, it was a scourge of both Japan and China. However, it is now very restricted in its distribution. It's actually been eliminated from Japan. And there are small foci in China, and in the Philippines. This parasite is very interesting, because not only does it infect human beings, but it's also zoonotic, and so the adult worms can be found in domestic animals. Two other less important species are Schistosoma intercalatum, which is found in Africa, and S. mekongi in Asia, as you could expect, in the Mekong River.