Is fully recommend seeing a doctor to confirm your record and recommended vaccinations before travel.
A yellow fever vaccination certificate may be required only if you have traveled within the last 90 days, to any of the following countries:
Angola, Bolivia, Benin, Burkina, Cameroon, Colombia, Democratic Republic of Congo, Ecuador, French Guyana, Gabon, Ghana, Gambia, Republic of Guinea, Liberia, Nigeria, Peru, Sierra Leone, Sudan or Venezuela.
Yellow fever vaccination is advisable if your destinations in Brazil include any of the following Brazilian states: Acre, Amapá, Amazonas, Federal District of Brasilia, Goiás, Maranhão, Mato Grosso, Mato Grosso do Sul, Pará, Rondônia, Roraima and/or Tocantins.
Please, contact the Brazilian embassy near from you to confirm these infos.
Note: In case you will need to have this vaccination, please note that it has to be applied 10 days before enter the country.
Also, is recommend bringing a quinolone antibiotic to stop traveler's diarrhea.