Levamisole works as a nicotinic acetylcholine receptor agonist that causes continued stimulation of the parasitic worm muscles, leading to paralysis. This changes the behavior of the parasite in the body, systemically.
Levamisole forces threadworms to migrate towards skin or mucous tissue.
There they can be killed using IVM, FenBen, OXBen. There seams to be a cycle associated with the optimum time of the month. Early clearing requires multiple doses, some do doses daily. Later, exact days of the month cycle seams to be more effective.
Pyrantel in yogurt nPPZ slug 6PM clears birth cycle in GI, seams to make replication more difficult, suppression of threadworm and redworm cycle.
Other immune supplements may help make this approach much more effective.