Two years ago I wrote two posts about Brazilian geocoding and mapping here and here. Since that time, the Brazilian government website IBGE.gov.br seems to have removed their city level shapefiles, or at least, I cannot find them. LUCKILY, I kept a copy of the polygon data set that I created.
Shown below is the entire country. Click a state to drill down. There are no metrics in this data set. The assumption here is that you will use data blending for your analysis. I also make no warrants or guarantees about the accuracy of the polygon data or about how up to date the boundaries are.