When Dr. Crother and I participated in field courses in Costa Rica through the Organization for Tropical Studies , which has educated thousands of tropical biologists since the 60s, we were advised to have a tetanus booster and a yellow fever vaccine. Malaria prophylaxis was only suggested. Health Information for Travelers to Mexico and Central America Belize, Costa Rica, El Salvador, Guatemala, Honduras, Mexico, Nicaragua, Panama Food and waterborne diseases are the number one cause of illness in travelers. Travelers' diarrhea can be caused by viruses, bacteria, or parasites, which are found throughout the region and can contaminate food or water. Make sure your food and drinking water are safe.
Malaria is a preventable infection that can be fatal if left untreated.
Risk for malaria exists all year in the rural lowlands and in some urban areas of the countries in this region. Travelers to these areas and to Panama west of the Canal Zone should take chloroquine to prevent malaria. For detailed information about specific locations, see Malaria in Central America and Mexico. A yellow fever vaccination certificate may be required for entry into certain of these countries if you are traveling from a country in tropicalSouth America or sub-Saharan Africa. For detailed information, see Comprehensive Yellow Fever Vaccination Requirements.