It used to be only the Miracidia stage, creates HCG - cause of Anasarca - widespread swelling of the skin, but thanks to the US Army and Myco Fermentans the larger adults also create it.
You should be able to wipe out early stage in a few treatments but if you have Sr Adults infected with Myco Fermentans then everytime you kill one you get more HCG dumped as well as that Fluoride compount and other stuff in that post.