Once discovered putzis are easily removed. A dab of Vaseline followed by a good squeeze will do the trick. The Vaseline stops the maggot from being able to breathe and out it pops. Unfortunately for some, myself included, the tropics can cause many a strange sore to mysteriously appear so an immediate correct diagnosis isn't always going to happen. The larvae that burrowed in to my back as a young girl and teen had a grand old time. They were undiagnosed for so long they grew to be a few inches long and what they finally left behind, once extracted, wasn't a pretty sight. It was also quite painful.
To avoid becoming the host of Putzi fly offspring, the simple solution is to iron all your clothes (including underwear). The heat of the iron kills the eggs. This isn't always possible while traveling so dry your clothes inside to avoid the putzi flies laying their eggs in them.
For more details on the larvae stage see the Merck Veterinary Manual.