Depending on where she is traveling, I might be concerned about actually contracting diseases that there are vaccines for. For example, depending on the season and city, yellow fever or typhoid can be a big problem. I know vaccines don't have a 100% effective rate, and have met someone who was vaccinated against typhoid, yet still contracted it.
Unless coming from certain countries, vaccines for people traveling to Brazil are not mandatory. I forget where I have seen it (maybe on the WHO website?) but there are certain countries in Africa etc where you have to have a yellow fever vaccination certificate to enter Brazil.
Vaccines (other than yellow fever and coming from those countries) arent required by law for foreigners. I'm an expat living in Brazil and haven't had anyone ever ask to see my vaccination card, or anything, coming or going, or even going to see a doctor.
If she's going to the Amazon, do have her take anti-malarials! Malaria is pretty common and pretty nasty, and not something you want your daughter to experience on what should be a fun trip!