Re-reading what I wrote yesterday, i think that i was reacting pretty harshly for some reason. In order to be more balanced and constructive, I would like to leave another link here that has several different sources available for anyone who wishes to learn more about host-parasite relationships and parasite general information, from much more definitive and complete background sources. I especially recommend the ones which are NOT specially about just "schistosomiasis", but more about parasites in general.
http://www.homeandbodyhealth.com/Parasites.html
Altho, this site will eventually be used to market healthcare products, I have no interest in those products, and I only wish to point out that this is good information on parasites.