There are two reasons to have the Yellow Fever vaccination before coming to Brazil:

1) You are coming from a country which has Yellow Fever and Brazil will not let you enter without proof that you have been vaccinated

2) You are going somewhere in Brazil that is having an outbreak and want to protect yourself

I would advise checking with the nearest Brazilian Consulate/Embassy.

As far as #1, it appears from this map that Chile does not have Yellow Fever.

nathnac.org/yellow_book/endemic_zone_s_ameri…

As for #2, as far as I know, there is no Yellow Fever outbreak in Brazil at the present time (S.A. winter 2008).

Again, check with the Embassy/Consulate of Brasil and/or a medical professional.

Well, it's a week late, but you might want to check this thread and up-date at the CDC website link:

tripadvisor.com/ShowTopic-g303444-i4551-k175…

The best advice you have received already; always consult with a knowledgeable health care professional before traveling, and, I might add, check the CDC site for up-dates prior to your departure.

Thanks for the link, and no, it is not too late. I am still thinking about it. Last summer (winter) there was an outbreak in Paraguay and in parts of Brazil (5 cases).

It is confusing because there are conflicting reports. No YF shots needed for Iguazu Argentina, so why would I need one crossing a few KMs into Brazil? Frankly, a YF shot warning is very bad for tourism, so I don´t know if Argentina is downplaying the need or is the CDC targeting Brazil.

Yellow Fever can occur everywhere the Aedes Aegypti mosquito (the same that transmits dengue fever) breeds well. This is also true for the northern part of Argentina. Obviously mosquitos have no idea about borders. Iguaçu is not in an endemic area, but there is a minimal risk (on both sides of the border). If you're so inclined get the shot.