My first instinct is the Nettle family Myriam, given the serious rash! The leaves do resemble a large nettle.
Look at Urera baccifera ..
https://sites.google.com/site/...
http://en.wikipedia.org/wiki/U...
http://biogeodb.stri.si.edu/bi...
The leaves appear to be broader in some, look at the lower smaller part of the plant in this link, there's several photos ..
http://herbaria.plants.ox.ac.u...
The photo on the following link is in the Tropical plants, Brazil, the stem looks ridged without spines ..
http://fm2.fieldmuseum.org/pla...
