Don't want to be an alarmist. I think the risk is very very small if you take precautions, but I do think this is worth mentioning:
Please be careful about staying in "lower end" accomodations, especially rural places with thatched roofs and other known hiding places for "vinchuca" bugs . Anyone traveling in South America should educate themselves on Chagas and know what the "vinchuca" bugs that spreads Chagas looks like.
A doc here (Bolivia) told me this:
1) First don't get bit by a vinchuca.
2) Second, if you do get bit by one, don't scratch it, gently clean it with alcohol ... then see a doctor asap. [I suppose a picture of the bug would help if you're uncertain].
3) If you catch an infection with a blood tests early enough you can cure it with anti-parasitics.
4) Just because you get bit by a "vinchuca", doesn't mean you'll definitely get Chagas