That is a concern, yes. Ants, mosquitos, and parasites you can't see. Though the wrong type of footwear can be even worse than barefoot in some cases. Straps/seams/whatever that ants can get caught up in. You're protected somewhat from them getting to your skin, but if/when they do it's harder to get them out. But more-so there are infection and disease problems from being barefoot in this type of environment. And most-so, there are lots of sharp and pokey things in the ground, often covered in a thin layer of mud.