It usually boils down to water! Even if your traveling from city to city the water can be different and upset the balance of your gut. Not to mention this is very common when you travel country to country as well. Actually, it's like very common, and often times why people bring bottled water. It's just easier on the stomach. In some places, you are required to boil your water before drinking and this is not just excluded to impoverished places and not excluded to only impoverished countries. ( for example if I go visit my mother I have to boil the water before drinking) Did you know up to fifty percent of indigenous tribal homes live without clean drinking water! That means they have to buy their water or boil their water before even taking a bath. At risk of getting sick. In Canada it's similar if not worse and Canada is the largest clean water resource. So I mean, it depends from country to country what has happened with the water too. Ah, water is a huge reason. Now, I'm certain, all sorts of sickness that people are not immune to and stress oh gosh that can bring on sick and it just happens sometimes.
