[UPDATE: Yellow fever alert]
I am reproducing the information on vaccines that appears at the Portal Brasileño de Turismo (run by the Brazilian government).
Yellow fever vaccine
For tourists who have been in transit over the past three months, or who are coming from certain countries – Angola, Benin, Bolivia, Burkina Faso, Cameroon, Colombia, Ecuador, Gabon, Gambia, Ghana, Guinea Bissau, French Guiana, Liberia, Nigeria, Peru, the Democratic Republic of the Congo, Sierra Leon, Sudan, Venezuela and Zaire -, an International Certificate of Vaccination against yellow fever is required.
The yellow fever vaccine is also recommended for all national and international tourists who intend to visit the following Brazilian states: Acre, Amazonas, Amapá, Federal District, Goiás, Maranhão, Mato Grosso do Sul, Pará, Rondônia, Roraima and Tocantins.
Not counting the cases mentioned above, no other vaccines are required for travellers entering Brazil.