Both are correct. It's not really you rubbing your eyes but you rubbing any part of your body. The vinchuca (bug) has a very weak digestive system, so it defecates seconds after eating, i.e. right after it bites you. It's the excrement that itches and by scratching yourself you incorporate the disease into your body.

Do the refugios in Mendoza have thatched roofs or many cracked walls? Maybe lukuki can let us know. The vinchuca can be easily spotted - its yellow and black excrement "paints" the area near the nest.