If the infestation doesn't come back, I don't see that it matters (just me, just sayin').
Consider this: Doctors often treat bacterial infections with antibiotics without knowing the "specific" bacteria causing the infection. What leads them is location and symptoms. If you don't get well in the prescribed period of time, what do you do? You go back, so they can "try" again. If you get well, it doesn't matter what you "had," because it's gone!