If you don't shave or wax your pubic hair, then now may be the time to start: No hair, nothing for the lice to hang onto.
For head hair, it's nut comb time (removes adults and eggs) or insecticide time. It can take a couple of weeks either way, and as long as you have them, 'close contact' can result in others getting them. You also need to put pillows etc into a hot wash, frequently.
If everyone you are getting into that contact with isn't getting treated, you just end up reinfecting each other.
If you have had an STI in your throat once, you can obviously get it again...