We arrived in China on Wednesday and on Sunday my colleague and I were both sick. We had done a lot of things right: Used bottled water for brushing teeth as well as drinking, avoided eating food from suspect sources, but we still got sick. AJ, my partner, had stomach problems, and I had "flu like symptoms", basically achey joints and a dry cough.
What we could have done better is carry a small bottle of hand sanitizer in our pants pockets when we were out and about. Public lavatories are not frequent and don't have the amenities were used to.
And we didn't pack prescription drugs with us before we left. You can go to your family doctor, explain what your about to embark upon and (s)he will write prescriptions for the most likely problems.
The dumb thing I did is that I have a company issued travel kit that contains:
Gentamicin Sulfate eye drops for eye infections.
Diphenhydramine, Benadryl, which you don't need a prescription for, and by the way the cheapest way to get this is in Tylenol-PM.
Loperamide, which is a little safer than Lomotil.
And finally, the big gun, Sulfamethoxazole/Trimethoprim. This is a powerful antibiotic which I would only use in an emergency.
I had this kit in a convenient zippered pouch and left it in my desk!!
Fortunately, we were still able to work, and were only knocked out of exploring the area for two days.
I had made a promise to AJ that my plan was to go in healthy, come out healthy, and don't let 'em kill us. Technically, I kept my promise, we just got sick in the middle.