If what the parasites "Want" is the escape the cave systems and a recently infected person can easily find the way out in a matter of hours (or days the timeframe isn't clear on it), then how come the cave demons have never got out? They are fast and can fly and they can swim extremely well, Jack himself led the crew in basically a straight line to the exit, so a bunch of flying amphibious monsters should have no trouble.
The team are professional cavers and divers, they know what to look for and how to find their way around. Plus, most of the creatures are far deeper into the caves, so by the time most of them end up in that far in, they've probably lost most of their sapience. Plus, that's simply the person infected's interpretation of the situation. It might simply be she doesn't quite understand what the parasite itself actually wants.
It's also possible that the contagion had done its job too well on the previous batch of infectees, and left them so perfectly adapted to the cave environment that they could no longer cope with conditions on the surface. There was only a narrow window of time for a host to take on the parasite's agenda of escape, yet still be capable of doing so.
