Hmmmm...medical issues can be worrisome! Botfly prevention...if you are going into dense jungle areas (to see mayan ruins, for example), wear a hat, and cover as much of skin as possible-long sleeve shirts, long pants, socks, etc. It may be hot, BUT, better than getting a botfly burrowing under your skin! As far as cholera, typhoid and malaria: I would check with your nearest travel medicine clinic. Large hospitals, university hospitals and teaching hospitals typically have them. If you're staying on Ambergris and San Pedro, I think you're risk is pretty low for any of those. But I am not a medical person, so best to check with travel clinic.