I recently tried to donate blood when a friend of mine had surgery. The woman at the center said I had to wait 12 months after visiting Belize because we had gone to the mainland to visit the Mayan Ruins. I remember while we were there driving into the town of Bomba, there was a sign posted by the health department about it being an area where malaria was present. They have a book at the centers that tells you where the acceptable areas are.