How do I know the flukes are treated?

[Averhoeven]

I have just completed treating 2 fish in QT for flukes (1 had them, but they were QTed together, the angel never even showed signs). They have now completed 2 rounds of prazipro 6 days apart after completing TTM. How do I know if they're treated and done? If I FW dip the affected one (that's how I knew the first time after I saw him shaking) and get nothing can I consider them cured? Is there a period of time after the 2nd treatment where you could get a false positive or negative? These 2 are my holy grail fish so I would love to have them in the tank for Christmas visitors, but I also don't want to risk the other fish if there's uncertainty.
Thanks!

 

[Humblefish]

Wait a week or two, freshwater dip the affected one, and if he's all clear you are good to go.