Yes, they do exist and yes I’ve managed to get them. Twice in fact, which I believe is twice too many times. You can recognise them as you get 2-3 tiny bites in an area in a triangle pattern and they’re really itchy. They are a real pain to get rid of and require lots of effort.
Basically you need to wash everything in your backpack in really hot water and put everything in the dryer. You also need to thoroughly clean your backpack, paying attention to things like seams where the little critters like to hide.
When I got them the first time, the manager of the hostel I was staying in knew exactly what to do. He made me take all my clothes off (including underwear) and put all my belongings into black rubbish bags which he then took straight to the laundry. He then presented me with some clothes which were clean but shall I say, had been around for a long long time. He also put my backpack in the freezer overnight which apparently kills the eggs.
The second time I got bed bugs I knew what to do so got onto them quicker, but even so I managed to bring them home with me back to New Zealand which was a whole different story. Let me just say, once you’ve got them in your house it’s REALLY DIFFICULT to get rid of them.
Interestingly enough I had soaked/sprayed my sleeping bag, inner sheet and backpack with ant-bedbug liquid before I left home but it obviously wasn’t effective. It’s really the luck of the draw as to whether you get them or not and doesn’t mean that a hostel is dirty as they have most likely been brought in by another traveler who hadn’t got around to dealing with them. (Note to self, don’t pick the bunk nearest to the door which usually gets the highest occupancy!)