Combine these regular workouts with a few long dayhikes with a small pack on the biggest hills you can find in your area. If you are prone to motion sickness bring along Dramamine. The train trips and long bus rides can be tough on weak stomachs. The sun is extremely intense at the altitudes we visit. We are in the rarefied air of the upper elevations.
Diarrhea is a common ailment in the third world.
Basically new strains of bacteria visit our intestines and our body has only one way to get rid of them. As noted earlier, ask your doctor about Bactrim and Cipro. In order to avoid dehydration you'll need to drink plenty of liquids. Remember that prevention is the best medicine. Try to avoid drinking water that wasn't either filtered, boiled or iodized.