Yes, here's the problem.  Also, I don't suppose any of these people could be fibbing about "not feeling well"??  None of the symptoms appear to be deadly, although diarrhea can cause dehydration but a smart person won't let that happen, right? 

"Here’s the problem. Officials admit the illness appears to be coming from contaminated water, and you can’t reduce that situation to a single virus. Forget the sophisticated analysis. Bad water contains bad things. A number of them. If you didn’t clean up the water in the first place, you’re going to have trouble.The norovirus, as an explanation, is a convenient cover story. It seems to explain the outbreak of illness---but it doesn’t.The virus hunters at the CDC are trained to look for the single viral culprit. That’s what they always do. They’re medical, not environmental. They don’t want to find the true answer when it’s something in the environment, because medical solutions don’t work. You have to clean up the water."

Yes sirreeee Bob, you hafta clean up the water. CDC doesn't DEAL IN WATER so they won't say anything - it ain't their field so they feel it's not on their radar either.  Let's just admit once and for all that the CDC is a useless, money-sucking entity and be done with it.

Great story.  https://jonrappoport.wordpress.com/2018/02/06/whats-behind-the-norovirus-outbreak-at-the-olympics/