Hi jood
I've done The Master Cleanse for 10 days.It was a great experience which left me feeling weak but squeaky clean, but no, I would not do additional parasite cleansing at the same time. If you're concerned about parasites, The Master Cleanse will rid you of some of them, but I for one would do a parasite cleanse following the Master Cleanse. It just makes sense to me to strike at the buggers with anti-parasitics once they're weakened from the Master Cleanse.
Best of luck,
paul