My parents lived in Mexico and I've traveled there a number of times...you have to be far more careful in Mexico and most Latin American countries than in any European country.
Bottled water is a must. This means using it to brush your teeth, too. No salads or uncooked vegies. If you can't peel the fruit yourself, don't eat it. This means no fresh-squeezed OJ or other juices (unless they come from a can). Even with all these precautions, you can still get sick.
My Crohn's-free best friend suffers, still, from the repercussions of an intestinal bacterial infection she picked up in Mexico...and had treated with Cipro...three years ago.
Daughter (20) Dx'd Crohn's 3/06. Misdiagnosed for two years, including by top pediatric Crohn's specialist as stress and needing more fiber but landed in hospital in 3/06 with cramps, vomiting, stricture. Now in remission with Entocort 3 mg (one pill), SCD multivitamin, yogurt, vit D3 1800IU, 900+ mg calcium, 50 mg B complex vit, 25 mg iron. No longer on SCD diet.