I was lucky. I was one of the people who didn't poop and puke on the trip.
By poop, I don't mean your daily constituional, I mean the kind that makes you worry about leaving your loo for any length of time.
At one point we thought people weren't used to the water or the food. Then we thought there was some sort of bug going around. It did seem to travel.
The only thing that happened to me was that I got a sore throat, briefly, that turned into a cough and respiratory distress. I lost my voice, or nearly so, for about two days. While others on the trip may have counted that as a blessing, I found it to be detrimental. I couldn't speak. Do you know what that does to a professor? My profession is speaking and communicating. Not being able to do that sucks.
That said, I would glady give up my voice to prevent poopin' and pukin'.