Should I get a mattress encasement for camp bunk mattress?

Hi, I’m going on a weekend retreat in a few weeks that’ll be held at a YMCA camp. We’ll be sleeping in bunks in cabins. Being a bit paranoid about the possibility of bedbugs, is it wise to buy a mattress encasement in case the mattress I’ll be sleeping on has bedbugs? Do they actually prevent BBs from getting out if they’re in a mattress? Thanks for the advice.