Vaccination
Keep in mind that a vaccine is never 100% effective. Precaution remains the best prevention (avoid eating raw food!). Although I was vaccinated, I caught typhoid during my stay in Bolivia!
Malaria
Chagas' disease (American trypanosomiasis)
Yellow fever
Leishmaniasis
Dengue fever
Rabies
Hepatitis A
Typhoid fever
Travelers´ Diarrhea
Altitude sickness