As a teacher, you learn one fact about changing your job. You are going to get sick. Not of life, or of the job (though sometimes that does happen), no: literally, you will get physically sick. See, here’s how that happens:
When you work in one school for a number of years, your body develops antibodies against all the local germs that the darling kiddies you are working with (regardless of their age) bring to school and share with all and sundry – including you. So, after a few years, you manage to stay reasonably well, because you have already suffered thorough all the local varieties of common cold, influenza, etc., etc., etc., and now you are mostly immune and can stay mostly healthy.
When you change your job, and go to a new school, guess what you are meeting along with all those interesting new people? Yep. All those uninteresting, new, local microbes. You are going to get sick. The fact that you are working with children, and lots and lots of them (nearly 800 in this new school) does not help that situation. Children are still learning to wash their hands and blow their noses, and when to stay home and be sick in private, and when it is OK to be sick and come to school (like, virtually never). So you quite literally shake hands with lots and lots of new (to you) varieties of germs. Now multiply that truth by the interesting complexities of germ adaptation in totally new countries in different parts of the globe.
You got it. No, actually, I got it.