Hmm. Well, just to reiterate and give feedback somethings. The clorsulon didn't do anything. I did find the thin tegument layers but there are some pretty serious skin disorder side effects that can come from taking this type of drug and I wasn't willing to go past the recommended one time dosage. I didn't get any dead flukes from it.
And regarding the negative test result. The lab for that species tested the IgG antibodies which are a result of antigen presentation. It seems like this should have happened at one point. I'm not sure. Also, the IgG antibodies take time to be developed which can take a few months to happen. Also, I was taking an antiparasitic drug at the time but since it was testing antibodies and not actual parasites then it shouldn't have mattered. So, I don't know. You can call the lab and talk with the lab tech to get more information about each individual test. I think the cathepsin L antigen marker is the one that has had good results. I just haven't found a lab to run that. just wanted to give some feedback.
David