It takes repeated treatment.Tapeworms travel and lays eggs..So the treatment has to saturate the system for a extended amout of time and sometimes up to a year..If you see them,great...You vacated the worms in the colon...But those eggs....20 years and i still expell them.And liverfluke...I just have not treated and a consistent form for a lengthy time. But very New Revelations have been storming me here lately, and I'm not sure that you will ever be able to totally exterminate these things, but probably more so as keeping them under control. Evidence is showing now that parasites and cancer are pretty much the same snake.