Originally Posted by Dave NoCal

Just in case, see if you can purchase medical evacuation insurance for your trip. It typically doesn't coast that much but you could need it if you need state of the art care. A colleague was thrown from a horse in Argentina and fractured her spine. She was brought back by a medical team or a corporate-sized jet and made a full recovery.
I took a group of twelve to Mexico for three weeks and no one became ill. Still, Simcha's suggestion is a good one. Avoid ice, shellfish, raw, unpeeled fruit, food sold on the street. Get vaccinations early and, if you can, a shot of gamma globulin right before leaving.
Dave