Most parasite meds remain in the tissue long after you have stopped taking them. This would explain the parasite reduction when not taking meds.
I can't remember exactly but IVER is like 45 days and Albendazole is 60 days.
The turning point for me was taking the anti fungal Lufenuron. Once I started taking this the parasites seemed to dissipate. But it takes years depending on how long you have been infected. You just have to keep at it.
My lungs were plugged with hook worm larvae. This is the most common parasite found in the lungs