Brazil has issued a stamp on 17 april 1958 (opening of the Expo 58 happening).

the description of the stamp is as follows:

Value is 2.50Cr. Color is cobalt Blue. At left the official emblem of the Exhibition, a figure holding globe bearing the uneven star of the Exhibition; at right is a view of the Brazilian Pavilion; inscribed at top and right "EXPOSICAO UNIVERSAL / BRUXELAS 1958".

The stamp has been issued in sheets of 50 stamps at once.

The stamp has been engraved by Gultasio Ferreira da Silva, is 12 as perforation and is watermarked with BRAZIL* CORREIRO. The designer is Altificio de Souza Ferreire. 

For the good sake, see here an impressive mis perf:

And finally scan/picture of the full sheet of 50 stamps: